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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Feb. 15, 2019	Jun. 29, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	MLM
Entity Registrant Name	MARTIN MARIETTA MATERIALS INC
Entity Central Index Key	0000916076
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		62,430,548
Entity Public Float			$ 11,000,435,608.61

Consolidated Statements of Earnings - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenues	$ 4,244,265,000	$ 3,965,594,000	$ 3,818,749,000
Total cost of revenues	3,277,688,000	2,993,654,000	2,907,011,000
Gross Profit	966,577,000	971,940,000	911,738,000
Selling, general and administrative expenses	280,554,000	262,128,000	241,606,000
Acquisition-related expenses, net	13,479,000	8,638,000	909,000
Other operating (income) and expenses, net	18,193,000	(793,000)	8,043,000
Earnings from Operations	690,737,000	700,381,000	677,266,000
Interest expense	137,069,000	91,487,000	81,677,000
Other nonoperating income, net	(22,413,000)	(10,034,000)	(11,439,000)
Earnings before income tax expense (benefit)	576,081,000	618,928,000	607,028,000
Income tax expense (benefit)	105,705,000	(94,457,000)	181,584,000
Consolidated net earnings	470,376,000	713,385,000	425,444,000
Less: Net earnings attributable to noncontrolling interests	378,000	43,000	58,000
Net Earnings Attributable to Martin Marietta	$ 469,998,000	$ 713,342,000	$ 425,386,000
Net Earnings Attributable to Martin Marietta Per Common Share (see Note A)
Basic attributable to common shareholders	$ 7.46	$ 11.30	$ 6.66
Diluted attributable to common shareholders	$ 7.43	$ 11.25	$ 6.63
Weighted-Average Common Shares Outstanding
Basic	62,895	62,932	63,610
Diluted	63,147	63,217	63,861
Products and Services
Total revenues	$ 3,980,351,000	$ 3,723,478,000	$ 3,578,650,000
Total cost of revenues	3,009,810,000	2,749,488,000	2,665,029,000
Freight
Total revenues	263,914,000	242,116,000	240,099,000
Total cost of revenues	$ 267,878,000	$ 244,166,000	$ 241,982,000

Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Consolidated Net Earnings	$ 470,376	$ 713,385	$ 425,444
Defined benefit pension and postretirement plans:
Net loss arising during period, net of tax of $(7,640), $(2,625) and $(19,734), respectively	(22,877)	(8,052)	(31,620)
Amortization of prior service credit, net of tax of $(493), $(547) and $(617), respectively	(1,478)	(883)	(992)
Amortization of actuarial loss, net of tax of $3,156, $5,271 and $4,437, respectively	9,463	8,503	7,138
Amount recognized in net periodic pension cost due to settlement, net of tax of $734, $8 and $44 respectively	2,202	13	71
Amount recognized in net periodic pension cost due to special plan termination benefits, net of tax of $0, $0 and $293, respectively			471
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(12,690)	(419)	(24,932)
Foreign currency translation (loss) gain	(2,052)	1,140	(898)
Amortization of terminated value of forward starting interest rate swap agreements into interest expense, net of tax of $178, $571 and $541, respectively	280	872	826
Other Comprehensive Income (Loss), Net of Tax	(14,462)	1,593	(25,004)
Consolidated comprehensive earnings	455,914	714,978	400,440
Less: Comprehensive earnings attributable to noncontrolling interests	391	53	119
Comprehensive Earnings Attributable to Martin Marietta	$ 455,523	$ 714,925	$ 400,321

Consolidated Statements of Comprehensive Earnings (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss arising during period, tax	$ (7,640)	$ (2,625)	$ (19,734)
Amortization of prior service credit, tax	(493)	(547)	(617)
Amortization of actuarial loss, tax	3,156	5,271	4,437
Amount recognized in net periodic pension cost due to settlement, tax	734	8	44
Amount recognized in net periodic pension cost due to special plan termination benefits, tax	0	0	293
Amortization of terminated value of forward starting interest rate swap agreements into interest expense, tax	$ 178	$ 571	$ 541

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 44,892	$ 1,446,364
Accounts receivable, net	523,276	487,240
Inventories, net	663,035	600,591
Other current assets	134,613	96,965
Total Current Assets	1,365,816	2,631,160
Property, plant and equipment, net	5,157,229	3,592,813
Goodwill	2,399,118	2,160,290
Other intangibles, net	501,282	506,349
Other noncurrent assets	127,974	101,899
Total Assets	9,551,419	8,992,511
Current Liabilities:
Accounts payable	210,808	183,638
Accrued salaries, benefits and payroll taxes	51,434	44,255
Pension and postretirement benefits	9,942	13,652
Accrued insurance and other taxes	63,543	64,958
Current maturities of long-term debt	390,042	299,909
Other current liabilities	60,981	87,804
Total Current Liabilities	786,750	694,216
Long-term debt	2,730,439	2,727,294
Pension, postretirement and postemployment benefits	134,469	244,043
Deferred income taxes, net	705,564	410,723
Other noncurrent liabilities	244,785	233,758
Total Liabilities	4,602,007	4,310,034
Equity:
Common stock ($0.01 par value; 100,000,000 shares authorized; 62,515,000 and 62,873,000 shares outstanding at December 31, 2018 and 2017, respectively)	624	628
Preferred stock ($0.01 par value; 10,000,000 shares authorized; no shares outstanding)
Additional paid-in capital	3,396,059	3,368,007
Accumulated other comprehensive loss	(143,579)	(129,104)
Retained earnings	1,693,259	1,440,069
Total Shareholders’ Equity	4,946,363	4,679,600
Noncontrolling interests	3,049	2,877
Total Equity	4,949,412	4,682,477
Total Liabilities and Equity	$ 9,551,419	$ 8,992,511

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares outstanding	62,515,000	62,873,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Consolidated net earnings	$ 470,376	$ 713,385	$ 425,444
Adjustments to reconcile consolidated net earnings to net cash provided by operating activities:
Depreciation, depletion and amortization	344,033	297,162	285,253
Stock-based compensation expense	29,253	30,460	20,481
(Gain) Loss on divestitures and sales of assets	(39,260)	(19,366)	410
Deferred income taxes, net	85,063	(239,056)	67,050
Noncash portion of asset and portfolio rationalization charge	16,970
Other items, net	(8,891)	(13,437)	(18,023)
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable, net	(10,617)	(29,329)	(25,072)
Inventories, net	(21,984)	(78,966)	(47,381)
Accounts payable	20,148	(17,874)	(8,116)
Other assets and liabilities, net	(179,943)	14,619	(11,106)
Net Cash Provided by Operating Activities	705,148	657,598	688,940
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(375,954)	(410,325)	(387,267)
Acquisitions, net of cash acquired	(1,642,137)	(12,095)	(174,522)
Proceeds from divestitures and sales of assets	69,114	35,941	6,476
Payment of railcar construction advances	(79,351)	(43,594)	(82,910)
Reimbursement of railcar construction advances	79,351	43,594	82,910
Investments in life insurance contracts, net	771	280	293
Net Cash Used for Investing Activities	(1,948,206)	(386,199)	(555,020)
Cash Flows from Financing Activities:
Borrowings of long-term debt	1,000,000	2,408,830	560,000
Repayments of long-term debt	(910,052)	(1,065,048)	(449,306)
Payments of deferred acquisition consideration	(6,707)	(2,774)
Debt issuance costs	(3,892)	(2,204)	(2,300)
Change in bank overdraft			(10,235)
Payments on capital lease obligations	(3,486)	(3,543)	(3,364)
Dividends paid	(116,436)	(108,852)	(105,036)
Purchase of the noncontrolling interest in the existing joint venture	(12,800)
Distributions to owners of noncontrolling interest			(400)
Contributions by noncontrolling interest to joint venture		212	44
Repurchase of common stock	(100,377)	(99,999)	(259,228)
Proceeds from exercise of stock options	7,201	10,110	27,257
Shares withheld for employees' income tax obligations	(11,865)	(11,805)	(9,723)
Net Cash (Used for) Provided by Financing Activities	(158,414)	1,124,927	(252,291)
Net (Decrease) Increase in Cash and Cash Equivalents	(1,401,472)	1,396,326	(118,371)
Cash and Cash Equivalents, beginning of year	1,446,364	50,038	168,409
Cash and Cash Equivalents, end of year	$ 44,892	$ 1,446,364	$ 50,038

Consolidated Statements of Total Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Earnings	Retained Earnings	Total Shareholders' Equity	Noncontrolling Interests
Beginning Balance at Dec. 31, 2015	$ 4,060,177	$ 643	$ 3,287,827	$ (105,622)	$ 874,436	$ 4,057,284	$ 2,893
Beginning Balance (in shares) at Dec. 31, 2015		64,479,000
Consolidated net earnings	425,444				425,386	425,386	58
Other comprehensive (loss) earnings	(25,004)			(25,065)		(25,065)	61
Dividends declared ($1.64 in 2016 and $1.72 in 2017 & 1.84 in 2018 per common share)	(105,036)				(105,036)	(105,036)
Issuances of common stock for stock award plans	26,112	$ 3	26,109			26,112
Issuances of common stock for stock award plans (in shares)		285,000
Repurchases of common stock	$ (259,228)	$ (16)			(259,212)	(259,228)
Repurchases of common stock, Shares	(1,587,987)	(1,588,000)
Stock-based compensation expense	$ 20,481		20,481			20,481
Distributions to owners of noncontrolling interest	(400)						(400)
Contribution from owners of noncontrolling interest	44		44			44
Ending Balance at Dec. 31, 2016	4,142,590	$ 630	3,334,461	(130,687)	935,574	4,139,978	2,612
Ending Balance (in shares) at Dec. 31, 2016		63,176,000
Consolidated net earnings	713,385				713,342	713,342	43
Other comprehensive (loss) earnings	1,593			1,583		1,583	10
Dividends declared ($1.64 in 2016 and $1.72 in 2017 & 1.84 in 2018 per common share)	(108,852)				(108,852)	(108,852)
Issuances of common stock for stock award plans	14,893	$ 2	14,891			14,893
Issuances of common stock for stock award plans (in shares)		155,000
Shares withheld for employees' income tax obligations	(11,805)		(11,805)			(11,805)
Repurchases of common stock	$ (99,999)	$ (4)			(99,995)	(99,999)
Repurchases of common stock, Shares	(457,742)	(458,000)
Stock-based compensation expense	$ 30,460		30,460			30,460
Contribution from owners of noncontrolling interest	212						212
Ending Balance at Dec. 31, 2017	$ 4,682,477	$ 628	3,368,007	(129,104)	1,440,069	4,679,600	2,877
Ending Balance (in shares) at Dec. 31, 2017	62,873,000	62,873,000
Consolidated net earnings	$ 470,376				469,998	469,998	378
Other comprehensive (loss) earnings	(14,462)			(14,475)		(14,475)	13
Dividends declared ($1.64 in 2016 and $1.72 in 2017 & 1.84 in 2018 per common share)	(116,436)				(116,436)	(116,436)
Issuances of common stock for stock award plans	14,245	$ 1	14,244			14,245
Issuances of common stock for stock award plans (in shares)		163,000
Shares withheld for employees' income tax obligations	(11,865)		(11,865)			(11,865)
Repurchases of common stock	$ (100,377)	$ (5)			(100,372)	(100,377)
Repurchases of common stock, Shares	(521,140)	(521,000)
Stock-based compensation expense	$ 29,253		29,253			29,253
Noncontrolling interest acquired in business combination	9,001						9,001
Purchase of the noncontrolling interest in the existing joint venture	(12,800)		(3,580)			(3,580)	(9,220)
Ending Balance at Dec. 31, 2018	$ 4,949,412	$ 624	$ 3,396,059	$ (143,579)	$ 1,693,259	$ 4,946,363	$ 3,049
Ending Balance (in shares) at Dec. 31, 2018	62,515,000	62,515,000

Consolidated Statements of Total Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Stockholders Equity [Abstract]
Cash dividends declared per common share	$ 1.84	$ 1.72	$ 1.64

Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Accounting Policies

Notes to Financial Statements

Note A: Accounting Policies

Organization. Martin Marietta (the “Company”) is a natural resource-based building materials company. The Company supplies aggregates (crushed stone, sand and gravel) through its network of more than 300 quarries, mines and distribution yards to its customers in 31 states, Canada, the Bahamas and the Caribbean Islands. In the western United States, Martin Marietta also provides cement and downstream products, namely, ready mixed concrete, asphalt and paving services, in markets where the Company also has a leading aggregates position. Specifically, the Company has two cement plants and four cement distribution facilities in Texas, and 140 ready mixed concrete plants and nine asphalt plants in Texas, Colorado, Louisiana and Arkansas. Paving services are exclusively in Colorado. The Company’s heavy-side building materials are used in infrastructure, nonresidential and residential construction projects. Aggregates are also used in agricultural, utility and environmental applications and as railroad ballast. The aggregates, cement, ready mixed concrete and asphalt and paving product lines are reported collectively as the “Building Materials” business. As of December 31, 2018, the Building Materials business contains the following reportable segments: Mid-America Group, Southeast Group and West Group. The Mid-America Group operates in Indiana, Iowa, northern Kansas, Kentucky, Maryland, Minnesota, Missouri, eastern Nebraska, North Carolina, Ohio, Pennsylvania, South Carolina, Virginia, Washington and West Virginia. The Southeast Group has operations in Alabama, Florida, Georgia, Tennessee, Nova Scotia and the Bahamas. The West Group operates in Arkansas, Colorado, southern Kansas, Louisiana, western Nebraska, Nevada, Oklahoma, Texas, Utah and Wyoming. In addition to these operations, the Company sells to customers in New York, Delaware, New Mexico and Mississippi. The following states accounted for 72% of the Building Materials business’ 2018 total revenues: Texas, Colorado, North Carolina, Georgia and Iowa.

The Company also operates a Magnesia Specialties business, which produces magnesia-based chemical products used in industrial, agricultural and environmental applications, and dolomitic lime sold primarily to customers in the steel and mining industries. Magnesia Specialties’ production facilities are located in Ohio and Michigan, and products are shipped to customers worldwide.

Use of Estimates. The preparation of the Company’s consolidated financial statements in conformity with accounting principles generally accepted in the United States (U.S. GAAP) requires management to make certain estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangible assets and other long-lived assets and assumptions used in the calculation of income tax expense (benefit), retirement and other postemployment benefits, stock-based compensation, the allocation of the purchase price to the fair values of assets acquired and liabilities assumed as part of business combinations and revenue recognition for service contracts. These estimates and assumptions are based on management’s judgment. Management evaluates estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and adjusts such estimates and assumptions when facts and circumstances dictate. Changes in credit, equity and energy markets and changes in construction activity increase the uncertainty inherent in certain estimates and assumptions. As future events and their effects cannot be determined with precision, actual results could differ significantly from estimates. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the consolidated financial statements for the period in which the change in estimate occurs.

Basis of Consolidation. The consolidated financial statements include the accounts of the Company and its wholly-owned and majority-owned subsidiaries. Partially-owned affiliates are either consolidated or accounted for at cost or as equity investments, depending on the level of ownership interest or the Company’s ability to exercise control over the affiliates’ operations. Intercompany balances and transactions between subsidiaries have been eliminated in consolidation.

Revenue Recognition. Total revenues include sales of materials and services provided to customers, net of discounts or allowances, if any, and include freight and delivery costs billed to customers. Revenues for product sales are recognized when control of the promised good is transferred to unaffiliated customers, typically when finished products are shipped. Revenues derived from the paving business are recognized using the percentage-of-completion method under the cost-to-cost approach. Under the cost-to-cost approach, recognized contract revenue is determined by multiplying the total estimated contract revenue by the estimated percentage of completion. Contract costs are recognized as incurred. The percentage of completion is determined on a contract-by-contract basis using project costs incurred to date as a percentage of total estimated project costs. The Company believes the cost-to-cost approach is appropriate, as the use of asphalt in a paving contract is relatively consistent with the performance of the related paving services. Paving contracts, notably with governmental entities, may contain performance bonuses based on quality specifications. Given the uncertainty of meeting the criteria until the performance obligation is completed, performance bonuses are recognized as revenues when and if determined to be achieved. Performance bonuses were not material to the Company’s consolidated results of operations for the years ended December 31, 2018, 2017 and 2016. Freight revenues reflect delivery arranged by the Company using a third party on behalf of the customer and are recognized consistently with the timing of the product revenues.

Freight and Delivery Costs. Freight and delivery costs represent pass-through transportation costs incurred and paid by the Company to third-party carriers to deliver products to customers. These costs are then billed to the customers.

Cash and Cash Equivalents. Cash equivalents are comprised of highly-liquid instruments with original maturities of three months or less from the date of purchase. The Company manages its cash and cash equivalents to ensure short-term operating cash needs are met and excess funds are managed efficiently. When operating cash is not sufficient to meet current needs, the Company borrows money under its credit facilities. The Company utilizes excess cash to either pay down credit facility borrowings or invest in money market funds, money market demand deposit accounts or offshore time deposit accounts. Money market demand deposits and offshore time deposit accounts are exposed to bank solvency risk.

Accounts Receivable. Accounts receivable are stated at cost. The Company does not typically charge interest on customer accounts receivable. The Company records an allowance for doubtful accounts, which includes a provision for probable losses based on historical write offs and a specific reserve for accounts deemed at risk. The Company writes off accounts receivable as bad debt expense when it becomes probable, based upon customer facts and circumstances, that such amounts will not be collected.

Inventories Valuation. Inventories are stated at the lower of cost or net realizable value. Costs for finished products and in process inventories are determined by the first-in, first-out method. Carrying value for expendable parts and supplies are determined by the weighted-average cost method. The Company records an allowance for finished product inventories based on an analysis of inventory on hand in excess of historical sales for a twelve-month or five-year average period and future demand. The Company also establishes an allowance for expendable parts over five years old and supplies over one year old.

Post-production stripping costs, which represent costs of removing overburden and waste materials to access mineral deposits, are a component of inventory production costs and recognized as incurred.

Property, Plant and Equipment. Property, plant and equipment are stated at cost.

The estimated service lives for property, plant and equipment are as follows:

Class of Assets		Range of Service Lives
Buildings		5 to 20 years
Machinery & Equipment		2 to 20 years
Land Improvements		5 to 60 years

The Company begins capitalizing quarry development costs at a point when reserves are determined to be proven or probable, economically mineable and when demand supports investment in the market. Capitalization of these costs ceases when production commences. Capitalized quarry development costs are classified as land improvements and depreciated over the life of the reserves.

The Company reviews relevant facts and circumstances to determine whether to capitalize or expense pre-production stripping costs when additional pits are developed at an existing quarry. If the additional pit operates in a separate and distinct area of the quarry, these costs are capitalized as quarry development costs and depreciated over the life of the uncovered reserves. Additionally, a separate asset retirement obligation is created for additional pits when the liability is incurred. Once a pit enters the production phase, all post-production stripping costs are charged to inventory production costs as incurred.

Mineral reserves and mineral interests acquired in connection with a business combination are valued using an income approach over the life of the reserves.

Depreciation is computed based on estimated service lives, principally using the straight-line method. Depletion of mineral reserves is calculated based on proven and probable reserves using the units-of-production method on a quarry-by-quarry basis.

Property, plant and equipment are reviewed for impairment whenever facts and circumstances indicate that the carrying amount of an asset group may not be recoverable. An impairment loss is recognized if expected future undiscounted cash flows over the estimated remaining service life of the related asset are less than the asset’s carrying value.

Repair and Maintenance Costs. Repair and maintenance costs that do not substantially extend the life of the Company’s plant and equipment are expensed as incurred.

Goodwill and Intangible Assets. Goodwill represents the excess purchase price paid for acquired businesses over the estimated fair value of identifiable assets and liabilities. Other intangibles represent amounts assigned principally to contractual agreements and are amortized ratably over periods based on related contractual terms. If an other intangible asset is deemed to have an indefinite life, it is not amortized.

The Company’s reporting units, which represent the level at which goodwill is tested for impairment, are based on the operating segments of the Building Materials business. Goodwill is assigned to the respective reporting unit(s) based on the location of acquisitions at the time of consummation. Goodwill is tested for impairment by comparing the reporting unit’s fair value to its carrying value, which represents Step 1 of a two-step approach. However, prior to Step 1, the Company may perform an optional qualitative assessment and evaluate macroeconomic conditions, industry and market conditions, cost factors, overall financial performance and other business or reporting unit-specific events. If the Company concludes it is more-likely-than-not (i.e., a likelihood of more than 50%) that a reporting unit’s fair value is higher than its carrying value, the Company does not perform any further goodwill impairment testing for that reporting unit. Otherwise, the Company proceeds to Step 1 of its goodwill impairment analysis. The Company may bypass the qualitative assessment for any reporting unit in any period and proceed directly with the quantitative calculation in Step 1. If the reporting unit’s fair value exceeds its carrying value, no further calculation is necessary. A reporting unit with a carrying value in excess of its fair value constitutes a Step 1 failure and will lead to an impairment charge.

The carrying values of goodwill and other indefinite-lived intangible assets are reviewed annually, as of October 1, for impairment. An interim review is performed between annual tests if facts and circumstances indicate potential impairment. The carrying value of other amortizable intangibles is reviewed if facts and circumstances indicate potential impairment. If a review indicates the carrying value is impaired, a charge is recorded.

Retirement Plans and Postretirement Benefits. The Company sponsors defined benefit retirement plans and also provides other postretirement benefits. The Company recognizes the funded status, defined as the difference between the fair value of plan assets and the benefit obligation, of its pension plans and other postretirement benefits as an asset or liability on the consolidated balance sheets. Actuarial gains or losses that arise during the year are not recognized as net periodic benefit cost in the same year, but rather are recognized as a component of accumulated other comprehensive earnings or loss. Those amounts are amortized over the participants’ average remaining service period and recognized as a component of net periodic benefit cost. The amount amortized is determined using a corridor approach and represents the excess over 10% of the greater of the projected benefit obligation or pension plan assets.

Stock-Based Compensation. The Company has stock-based compensation plans for employees and its Board of Directors. The Company recognizes all forms of stock-based awards that vest as compensation expense. The compensation expense is the fair value of the awards at the measurement date and is recognized over the requisite service period.

The fair value of restricted stock awards, incentive compensation stock awards and Board of Directors’ fees paid in the form of common stock are based on the closing price of the Company’s common stock on the awards’ respective grant dates. The fair value of performance stock awards is determined by a Monte Carlo simulation methodology.

In 2018, 2017 and 2016, the Company did not issue any stock options. For stock options issued prior to 2016, the Company used the accelerated expense recognition method. The accelerated recognition method requires stock options that vest ratably to be divided into tranches. The expense for each tranche is allocated to its particular vesting period.

Environmental Matters. The Company records a liability for an asset retirement obligation at fair value in the period in which it is incurred. The asset retirement obligation is recorded at the acquisition date of a long-lived tangible asset if the fair value can be reasonably estimated. A corresponding amount is capitalized as part of the asset’s carrying amount. The fair value is affected by management’s assumptions regarding the scope of the work required, inflation rates and quarry closure dates.

Further, the Company records an accrual for other environmental remediation liabilities in the period in which it is probable that a liability has been incurred and the appropriate amounts can be estimated reasonably. Such accruals are adjusted as further information develops or circumstances change. Generally, these costs are not discounted to their present value or offset for potential insurance or other claims or potential gains from future alternative uses for a site.

Income Taxes. Deferred income taxes, net, on the consolidated balance sheets reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, net of valuation allowances. The effect on deferred income tax assets and liabilities attributable to changes in enacted tax rates are charged or credited to income tax expense or benefit in the period of enactment.

Uncertain Tax Positions. The Company recognizes a tax benefit when it is more-likely-than-not, based on the technical merits, that a tax position would be sustained upon examination by a taxing authority. The amount to be recognized is measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. The Company’s unrecognized tax benefits are recorded in other liabilities on the consolidated balance sheets or as an offset to the deferred tax asset for tax carryforwards where available.

The Company records interest accrued in relation to unrecognized tax benefits as income tax expense. Penalties, if incurred, are recorded as operating expenses in the consolidated statements of earnings.

Sales Taxes. Sales taxes collected from customers are recorded as liabilities until remitted to taxing authorities and therefore are not reflected in the consolidated statements of earnings.

Start-Up Costs. Noncapital start-up costs for new facilities and products are charged to operations as incurred.

Warranties. The Company’s construction contracts usually contain warranty provisions covering defects in materials, design or workmanship that generally run from nine months to one year after project completion. Due to the nature of its projects, including contract owner inspections of the work both during construction and prior to acceptance, the Company has not experienced material warranty costs for these short-term warranties and therefore does not believe an accrual for these costs is necessary. The ready mixed concrete product line carries a longer warranty period, for which the Company has accrued an estimate of warranty cost based on experience with the type of work and any known risks relative to the projects. These costs were not material to the Company’s consolidated results of operations for the years ended December 31, 2018, 2017 and 2016.

Consolidated Comprehensive Earnings and Accumulated Other Comprehensive Loss. Consolidated comprehensive earnings for the Company consist of consolidated net earnings, adjustments for the funded status of pension and postretirement benefit plans, foreign currency translation adjustments and the amortization of the value of terminated forward starting interest rate swap agreements into interest expense, and are presented in the Company’s consolidated statements of comprehensive earnings.

Accumulated other comprehensive loss consists of unrecognized gains and losses related to the funded status of the pension and postretirement benefit plans, foreign currency translation and the unamortized value of terminated forward starting interest rate swap agreements, and is presented on the Company’s consolidated balance sheets.

The components of the changes in accumulated other comprehensive loss and related cumulative noncurrent deferred tax assets are as follows:

	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Total
years ended December 31 (add 000)	2018
Accumulated other comprehensive loss at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		(22,890	)		(2,052	)		—			(24,942	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		10,187			—			280			10,467
Other comprehensive (loss) earnings, net of tax		(12,703	)		(2,052	)		280			(14,475	)
Accumulated other comprehensive loss at end of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)

Cumulative noncurrent deferred tax assets at end of period	$	84,207		$	—		$	—		$	84,207

	2017
Accumulated other comprehensive loss at beginning of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)
Other comprehensive (loss) earnings before reclassifications, net of tax		(8,062	)		1,140			—			(6,922	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		7,633			—			872			8,505
Other comprehensive (loss) earnings, net of tax		(429	)		1,140			872			1,583
Accumulated other comprehensive loss at end of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)

Cumulative noncurrent deferred tax assets at end of period	$	79,938		$	—		$	178		$	80,116

	2016
Accumulated other comprehensive loss at beginning of period	$	(103,380	)	$	(264	)	$	(1,978	)	$	(105,622	)
Other comprehensive loss before reclassifications, net of tax		(31,678	)		(898	)		—			(32,576	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		6,685			—			826			7,511
Other comprehensive (loss) earnings, net of tax		(24,993	)		(898	)		826			(25,065	)
Accumulated other comprehensive loss at end of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)

Cumulative noncurrent deferred tax assets at end of period	$	82,044		$	—		$	749		$	82,793

Reclassifications out of accumulated other comprehensive loss are as follows:

years ended December 31 (add 000)	2018			2017			2016			Affected line items in the consolidated statements of earnings
Pension and postretirement benefit plans
Special plan termination benefits	$	-		$	-		$	764
Settlement charge		2,936			21			115
Amortization of:
Prior service credit		(1,971	)		(1,430	)		(1,609	)
Actuarial loss		12,619			13,774			11,575
		13,584			12,365			10,845		Other nonoperating income, net
Tax effect		(3,397	)		(4,732	)		(4,160	)	Income tax expense (benefit)
Total	$	10,187		$	7,633		$	6,685
Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	458		$	1,443		$	1,367		Interest expense
Tax effect		(178	)		(571	)		(541	)	Income tax expense (benefit)
Total	$	280		$	872		$	826

Earnings Per Common Share. The Company computes earnings per share (EPS) pursuant to the two-class method. The two-class method determines EPS for each class of common stock and participating securities according to dividends or dividend equivalents and their respective participation rights in undistributed earnings. The Company pays nonforfeitable dividend equivalents during the vesting period on its restricted stock awards and incentive stock awards made prior to 2016, which results in these being considered participating securities.

The numerator for basic and diluted earnings per common share is net earnings attributable to Martin Marietta, reduced by dividends and undistributed earnings attributable to the Company’s unvested restricted stock awards and incentive stock awards issued prior to 2016. The denominator for basic earnings per common share is the weighted-average number of common shares outstanding during the period. Diluted earnings per common share are computed assuming that the weighted-average number of common shares is increased by the conversion, using the treasury stock method, of awards issued to employees and nonemployee members of the Company’s Board of Directors under certain stock-based compensation arrangements if the conversion is dilutive.

The following table reconciles the numerator and denominator for basic and diluted earnings per common share:

years ended December 31

(add 000)	2018		2017		2016
Net earnings attributable to Martin Marietta	$	469,998	$	713,342	$	425,386
Less: Distributed and undistributed earnings attributable to unvested participating securities		806		2,029		1,775
Basic and diluted net earnings attributable to common shareholders attributable to Martin Marietta	$	469,192	$	711,313	$	423,611

Basic weighted-average common shares outstanding		62,895		62,932		63,610
Effect of dilutive employee and director awards		252		285		251
Diluted weighted-average common shares outstanding		63,147		63,217		63,861

New Accounting Pronouncements.

Revenue from Contracts with Customers

Effective January 1, 2018, the Company adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (ASU 2014-09), which changes the evaluation and accounting for revenue recognition under contracts with customers and enhances financial statement disclosures. The Company implemented ASU 2014-09 using the modified-retrospective approach and applied the guidance only to contracts that were not completed at the date of adoption. The adoption had an immaterial impact on the Company’s financial position and results of operations but required new disclosures (see Note B).

Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments

Effective January 1, 2018, the Company adopted ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (ASU 2016-15), which provides clarification or additional guidance on certain transactions and its classification on the statement of cash flows on a retrospective basis. In accordance with the adoption of ASU 2016-15, the Company reclassified the net activity related to company-owned life insurance policies to investing activities from operating activities in the consolidated statements of cash flows. The reclassifications reduced net cash provided by operating activities and net cash used for investing activities by $280,000 and $293,000 for the years ended December 31, 2017 and 2016, respectively.

Pending Accounting Pronouncements

Lease Standard

In February 2016, the Financial Accounting Standards Board (FASB) issued a new accounting standard, Accounting Standards Codification 842 – Leases (ASC 842), intending to improve financial reporting of leases and to provide more transparency into off-balance sheet leasing obligations. The guidance requires virtually all leases, excluding mineral interest leases, to be recorded as right-of-use assets and lease liabilities on the balance sheet and provides guidance on the recognition of lease expense and income. Effective January 1, 2019, ASC 842 requires the modified-retrospective transition approach, applying the new standard to all leases existing at the date of initial application. An entity may use either 1) ASC 842’s effective date or 2) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Company adopted the new standard effective January 1, 2019 and used the effective date as the date of initial application.

The new standard provides a number of practical expedients for transition and policy elections for ongoing accounting. The Company elected the “package of practical expedients”, which permits the Company to not reassess its prior conclusions about lease identification, lease classification and initial direct costs. The Company also elected the practical expedient pertaining to the use of hindsight, which resulted in including renewal options in the lease term that were not previously included in historical lease terms under the guidance prior to ASC 842. While the adoption of ASC 842 does not impact the expense over the life of a lease, the inclusion of renewal options with fixed escalation clauses in the lease term may impact the timing of expense recognition. Additionally, the Company elected the practical expedient that allows it not to evaluate land easements that existed or expired before the adoption of ASC 842 and that were not previously accounted for as leases. The standard provides policy election options for recognition exemption for short-term leases and separation of lease and non-lease components. The Company elected the short-term lease recognition exemption and to not separate lease and non-lease components for all underlying asset classes with the exception of railcars and fleet leases.

The Company expects the adoption of ASC 842 to increase its assets and liabilities on its consolidated balance sheet in the range of $475,000,000 to $550,000,000 as of January 1, 2019 and to require additional footnote disclosures pertaining to leasing activities beginning with the quarter ending March 31, 2019.

Revenue Recognition

12 Months Ended

Dec. 31, 2018

Revenue From Contract With Customer [Abstract]

Revenue Recognition

Note B: Revenue Recognition

Performance Obligations. Performance obligations are contractual promises to transfer or provide a distinct good or service for a stated price. The Company’s product sales agreements are single-performance obligations that are satisfied at a point in time. Performance obligations within paving service agreements are satisfied over time, primarily ranging from one day to two years. For product revenues and freight revenues, customer payment terms are generally 30 days from invoice date. Customer payments for the paving operations are based on a contractual billing schedule and are due 30 days from invoice date.

Future revenues from unsatisfied performance obligations at December 31, 2018, 2017 and 2016 were $78,142,000, $66,956,000 and $74,146,000, respectively, where the remaining periods to complete these obligations ranged from two months to 22 months, one month to 23 months and one month to 33 months, respectively.

Sales Taxes. The Company is deemed to be an agent when collecting sales taxes from customers. Sales taxes collected are initially recorded as liabilities until remitted to taxing authorities and are not reflected in the consolidated statements of earnings as revenues and expenses.

Revenue by Category. The following table presents the Company’s total revenues by category for each reportable segment:

years ended December 31	Products and Services		Freight		Total
(add 000)	2018
Mid-America Group	$	1,133,754	$	89,482	$	1,223,236
Southeast Group		409,543		13,839		423,382
West Group		2,168,418		141,506		2,309,924
Total Building Materials Business		3,711,715		244,827		3,956,542
Magnesia Specialties		268,636		19,087		287,723
Total	$	3,980,351	$	263,914	$	4,244,265

	2017
Mid-America Group	$	982,214	$	71,112	$	1,053,326
Southeast Group		348,675		13,880		362,555
West Group		2,139,867		139,856		2,279,723
Total Building Materials Business		3,470,756		224,848		3,695,604
Magnesia Specialties		252,722		17,268		269,990
Total	$	3,723,478	$	242,116	$	3,965,594

	2016
Mid-America Group	$	945,193	$	71,905	$	1,017,098
Southeast Group		304,722		16,356		321,078
West Group		2,086,351		137,164		2,223,515
Total Building Materials Business		3,336,266		225,425		3,561,691
Magnesia Specialties		242,384		14,674		257,058
Total	$	3,578,650	$	240,099	$	3,818,749

Service revenues, which solely include the paving operations located in Colorado, were $219,593,000, $245,276,000 and $216,827,000 for the years ended December 31, 2018, 2017 and 2016, respectively.

Contract Balances. Costs in excess of billings relate to the conditional right to consideration for completed contractual performance and are contract assets on the consolidated balance sheets. Costs in excess of billings are reclassified to accounts receivable when the right to consideration becomes unconditional. Billings in excess of costs relate to customers invoiced in advance of contractual performance and are contract liabilities on the consolidated balance sheets. The following table presents information about the Company’s contract balances:

December 31
(add 000)	2018		2017
Costs in excess of billings	$	1,975	$	1,310
Billings in excess of costs	$	6,743	$	7,204

Revenues recognized from the beginning balance of contract liabilities for the years ended December 31, 2018 and 2017 were $6,831,000 and $8,265,000, respectively.

Retainage, which primarily relates to the paving services, represents amounts that have been billed to customers but payment withheld until final acceptance of the performance obligation by the customer. Included on the Company’s consolidated balance sheets, retainage was $7,528,000 and $9,029,000 at December 31, 2018 and 2017, respectively.

Policy Elections. When the Company arranges third party freight to deliver products to customers, the Company has elected the delivery to be a fulfillment activity rather than a separate performance obligation. Further, the Company acts as a principal in the delivery arrangements and, as required by ASU 2014-09, the related revenues and costs are presented gross and are included in the consolidated statements of earnings.

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

Note C: Goodwill and Other Intangible Assets

The following table shows the changes in goodwill by reportable segment and in total:

December 31	Mid- America Group		Southeast Group			West Group			Total
(add 000)	2018
Balance at beginning of period	$	281,403	$	50,346		$	1,828,541		$	2,160,290
Acquisitions		150,552		94,774			—			245,326
Goodwill allocated to assets held for sale		—		—			(5,571	)		(5,571	)
Divestitures		—		(927	)		—			(927	)
Balance at end of period	$	431,955	$	144,193		$	1,822,970		$	2,399,118

	2017
Balance at beginning of period	$	281,403	$	50,346		$	1,827,588		$	2,159,337
Acquisitions		—		—			230			230
Purchase price adjustments		—		—			723			723
Balance at end of period	$	281,403	$	50,346		$	1,828,541		$	2,160,290

Intangible assets subject to amortization consist of the following:

December 31	Gross Amount		Accumulated Amortization			Net Balance
(add 000)	2018
Noncompetition agreements	$	6,314	$	(6,179	)	$	135
Customer relationships		65,550		(25,575	)		39,975
Operating permits		458,951		(36,111	)		422,840
Use rights and other		16,745		(11,243	)		5,502
Trade names		12,800		(9,697	)		3,103
Total	$	560,360	$	(88,805	)	$	471,555

	2017
Noncompetition agreements	$	6,274	$	(6,144	)	$	130
Customer relationships		45,955		(17,551	)		28,404
Operating permits		458,951		(26,435	)		432,516
Use rights and other		16,745		(10,176	)		6,569
Trade names		12,800		(7,947	)		4,853
Total	$	540,725	$	(68,253	)	$	472,472

Intangible assets deemed to have an indefinite life and not being amortized consist of the following:

December 31	Building Materials Business		Magnesia Specialties		Total
(add 000)	2018
Operating permits	$	6,600	$	—	$	6,600
Use rights		20,282		—		20,282
Trade names		280		2,565		2,845
Total	$	27,162	$	2,565	$	29,727
	2017
Operating permits	$	6,600	$	—	$	6,600
Use rights		24,432		—		24,432
Trade names		280		2,565		2,845
Total	$	31,312	$	2,565	$	33,877

During 2018, the Company acquired $21,760,000 of intangible assets, consisting of the following:

(add 000, except year data)	Amount		Weighted-average amortization period
Subject to amortization:
Customer relationships	$	20,620	12 years
Noncompetition agreements		40	10 years
Total subject to amortization		20,660	12 years

Not subject to amortization:
Use rights		1,100	N/A
Total	$	21,760

Total amortization expense for intangible assets for the years ended December 31, 2018, 2017 and 2016 was $13,911,000, $14,178,000 and $13,922,000, respectively.

The estimated amortization expense for intangible assets for each of the next five years and thereafter is as follows:

(add 000)
2019	$	13,203
2020		13,168
2021		12,462
2022		11,036
2023		10,592
Thereafter		411,094
Total	$	471,555

Business Combinations

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Business Combinations

Note D: Business Combinations

On April 27, 2018, the Company completed its acquisition of all of the equity interests in Bluegrass Materials Company (Bluegrass), the largest privately-held, pure-play aggregates company in the United States, for $1,617,357,000 in cash. Bluegrass’ operations included 22 active sites with more than 125 years of reserves, collectively, in Georgia, South Carolina, Tennessee, Maryland, Kentucky and Pennsylvania. These operations complement the Company’s existing southeastern footprint in its Mid-America and Southeast Groups and provide a new growth platform within Maryland and Kentucky. The Company reached an agreement with the U.S. Department of Justice (DOJ), approved by the federal district court for the District of Columbia, which resolved all competition issues with respect to the acquisition. Under the terms of the agreement with the DOJ, Martin Marietta divested its heritage Forsyth aggregates quarry, north of Atlanta, Georgia, and the legacy Bluegrass Beaver Creek aggregates quarry in western Maryland. In connection with the sale of its Forsyth quarry, the Company recognized a pretax gain of $14,785,000, which is included in acquisition-related expenses, net, in the consolidated statements of earnings and comprehensive earnings. There was no gain or loss on the Beaver Creek divestiture.

The Bluegrass acquisition was a stock transaction wherein the Company acquired 100% of the voting interest of the owners. The Company acquired cash, accounts receivable; inventories; property, plant and equipment, which primarily consists of mineral reserves; intangible assets; prepaid and other assets; and assumed accounts payable; accrued liabilities and deferred tax liabilities, net. The Company did not assume any of Bluegrass’ outstanding debt.

The Company determined fair values of the assets acquired and liabilities assumed. Although initial accounting for the business combination has been recorded, these amounts are subject to change during the measurement period which extends no longer than one year from the consummation date based on additional reviews, such as completion of deferred tax estimates based on the determination of the historic tax basis in assets acquired. Specific accounts subject to ongoing purchase accounting adjustments include goodwill and deferred income tax liabilities, net. Therefore, the measurement period remains open as of December 31, 2018. The following is a summary of the preliminary estimated fair values of the assets acquired and the liabilities assumed:

(add 000)
Assets:
Cash and cash equivalents	$	1,159
Receivables		25,479
Inventory		46,635
Other current assets		1,029
Property, plant and equipment		1,519,289
Intangible assets, other than goodwill		20,150
Goodwill		244,615
Total Assets		1,858,356
Liabilities:
Accounts payable and accrued expenses		17,978
Deferred income tax liabilities, net		214,020
Noncontrolling interest		9,001
Total Liabilities		240,999
Total Consideration	$	1,617,357

Goodwill represents the excess purchase price over the fair values of assets acquired and liabilities assumed and reflects projected operating synergies from the transaction, including expected overhead savings. None of the goodwill generated by the transaction will be deductible for income tax purposes.

Total revenues and earnings from operations attributable to acquired operations included in the consolidated statement of earnings for the year ended December 31, 2018 were $172,015,000 and $32,364,000, respectively.

Acquisition-related expenses, primarily related to Bluegrass, were $28,264,000 and $8,638,000 for the years ended December 31, 2018 and 2017, respectively.

Unaudited Pro Forma Financial Information

The unaudited pro forma financial information summarizes the combined results of operations for the Company and Bluegrass as though the companies were combined as of January 1, 2017. Financial information for periods prior to the April 27, 2018 acquisition date included in the pro forma earnings does not reflect any cost savings or associated costs to achieve such savings from operating efficiencies or synergies that result from the combination. Consistent with the assumed acquisition date of January 1, 2017, the pro forma financial results for the year ended December 31, 2017 include acquisition-related expenses of $28,088,000, the $14,785,000 gain on the required divestiture of assets and the one-time $18,738,000 increase in cost of sales for the sale of acquired inventory marked up to fair value as part of acquisition accounting.

The pro forma information does not purport to project the future financial position or operating results of the combined company. The pro forma financial information as presented below is for informational purposes only and is not indicative of the results of operations that would have been achieved if the acquisition had taken place at the beginning of fiscal year 2017.

year ended December 31
(add 000)	2018		2017
Total revenues	$	4,299,673	$	4,178,627
Net earnings attributable to Martin Marietta	$	489,526	$	691,719
Diluted earnings per share	$	7.75	$	10.94

On August 31, 2018, the Company purchased the remaining noncontrolling interest in a consolidated joint venture where the controlling interest was acquired as part of the Bluegrass acquisition.

Accounts Receivable, Net

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Accounts Receivable, Net

Note E: Accounts Receivable, Net

December 31
(add 000)	2018			2017
Customer receivables	$	514,094		$	480,073
Other current receivables		12,535			9,557
		526,629			489,630
Less: Allowances		(3,353	)		(2,390	)
Total	$	523,276		$	487,240

Of the total accounts receivable, net, balances, $2,478,000 and $2,819,000 at December 31, 2018 and 2017, respectively, were due from unconsolidated affiliates.

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventories, Net

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Inventories, Net

Note F: Inventories, Net

December 31

(add 000)	2018			2017
Finished products	$	615,719		$	552,999
Products in process and raw materials		66,920			62,761
Supplies and expendable parts		139,566			128,792
		822,205			744,552
Less: Allowances		(159,170	)		(143,961	)
Total	$	663,035		$	600,591

Property, Plant and Equipment, Net

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property, Plant and Equipment, Net

Note G: Property, Plant and Equipment, Net

December 31

(add 000)	2018			2017
Land and land improvements	$	1,089,675		$	974,622
Mineral reserves and interests		2,506,817			1,162,289
Buildings		162,098			154,564
Machinery and equipment		4,357,705			4,006,619
Construction in progress		178,668			199,973
		8,294,963			6,498,067
Less: Accumulated depreciation, depletion and amortization		(3,137,734	)		(2,905,254	)
Total	$	5,157,229		$	3,592,813

Included in these amounts are the gross asset value and accumulated amortization for machinery and equipment recorded under capital leases at December 31 as follows:

(add 000)	2018			2017
Machinery and equipment under capital leases	$	24,931		$	23,919
Less: Accumulated amortization		(14,524	)		(11,243	)
Total	$	10,407		$	12,676

Depreciation, depletion and amortization expense related to property, plant and equipment was $326,099,000, $279,808,000 and $268,935,000 for the years ended December 31, 2018, 2017 and 2016, respectively. Depreciation, depletion and amortization expense includes amortization of machinery and equipment under capital leases.

Interest expense of $3,017,000, $3,616,000 and $3,543,000 was capitalized during 2018, 2017 and 2016, respectively.

At December 31, 2018 and 2017, $56,235,000 and $57,665,000, respectively, of the Building Materials business’ net property, plant and equipment were located in foreign countries, namely the Bahamas and Canada.

Long-Term Debt

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Long-Term Debt

Note H: Long-Term Debt

December 31 (add 000)	2018			2017
4.25% Senior Notes, due 2024	$	396,398		$	395,814
7% Debentures, due 2025		124,272			124,180
3.450% Senior Notes, due 2027		296,939			296,628
3.500% Senior Notes, due 2027		494,765			494,352
6.25% Senior Notes, due 2037		228,094			228,033
4.250% Senior Notes, due 2047		591,541			591,688
Floating Rate Senior Notes, due 2019, interest rate of 3.29% and 2.13% at December 31, 2018 and 2017, respectively		299,260			298,102
Floating Rate Senior Notes, due 2020, interest rate of 3.30% and 2.10% at December 31, 2018 and 2017, respectively		298,956			298,227
6.60% Senior Notes, due 2018		-			299,871
Trade Receivable Facility, interest rate of 3.07% at December 31, 2018		390,000			-
Other notes		256			308
Total		3,120,481			3,027,203
Less: current maturities		(390,042	)		(299,909	)
Long-term debt	$	2,730,439		$	2,727,294

The Company’s 4.25% Senior Notes due 2024, 7% Debentures due 2025, 3.450% Senior Notes due 2027, 3.500% Senior Notes due 2027, 6.25% Senior Notes due 2037, 4.250% Senior Notes due 2047, Floating Rate Senior Notes due 2019 and Floating Rate Senior Notes due 2020 (collectively, the “Senior Notes”) are senior unsecured obligations of the Company, ranking equal in right of payment with the Company’s existing and future unsubordinated indebtedness. Upon a change-of-control repurchase event and a resulting below-investment-grade credit rating, the Company would be required to make an offer to repurchase all outstanding Senior Notes, with the exception of the 7% Debentures due 2025, at a price in cash equal to 101% of the principal amount of the Senior Notes, plus any accrued and unpaid interest.

On May 22, 2017, the Company issued $300,000,000 aggregate principal amount of Floating Rate Senior Notes due in 2020 (the “2020 Floating Rate Notes”) and $300,000,000 aggregate principal amount of 3.450% Senior Notes due in 2027 (the “3.45% Senior Notes”). The 3.45% Senior Notes may be redeemed in whole or in part prior to March 1, 2027 at a make-whole redemption price, or on or after March 1, 2027 at a redemption price equal to 100% of the principal amount of the notes to be redeemed, and in either case plus unpaid interest. The 2020 Floating Rate Notes bear interest at a rate, reset quarterly, equal to the three-month London Interbank Offered Rate (LIBOR) for U.S. Dollars plus 0.65% (or 65 basis points) and may not be redeemed prior to their stated maturity date of May 22, 2020.

On December 20, 2017, the Company issued $300,000,000 aggregate principal amount of Floating Rate Senior Notes due 2019 (the “2019 Floating Rate Notes”), $500,000,000 aggregate principal amount of 3.50% Senior Notes due 2027 (the “2027 3.50% Fixed Rate Notes”) and $600,000,000 aggregate principal amount of 4.25% Senior Notes due 2047 (the “2047 Fixed Rate Notes”). The net proceeds of the offering were used to finance, in part, the Bluegrass acquisition and to repay the $300,000,000 6.60% Senior Notes that matured April 15, 2018. The Company may not redeem the 2019 Floating Rate Notes prior to their stated maturity date of December 20, 2019.

The Senior Notes are carried net of original issue discount, which is being amortized by the effective interest method over the life of the issue. With the exception of the 2019 Floating Rate Senior Notes and the 2020 Floating Rate Senior Notes, the Senior Notes are redeemable prior to their respective maturity dates at a make-whole redemption price. The principal amount, effective interest rate and maturity date for the Senior Notes are as follows:

	Principal Amount (add 000)		Effective Interest Rate	Maturity Date
4.25% Senior Notes	$	400,000	4.25%	July 2, 2024
7% Debentures	$	125,000	7.12%	December 1, 2025
3.450% Senior Notes	$	300,000	3.47%	June 1, 2027
3.500% Senior Notes	$	500,000	3.53%	December 15, 2027
6.25% Senior Notes	$	230,000	6.45%	May 1, 2037
4.250% Senior Notes	$	600,000	4.27%	December 15, 2047
Floating Rate Senior Notes, due 2019	$	300,000	Three-month LIBOR + 0.50%	December 20, 2019
Floating Rate Senior Notes, due 2020	$	300,000	Three-month LIBOR + 0.65%	May 22, 2020

The Company has a credit agreement with JPMorgan Chase Bank, N.A., as Administrative Agent, Branch Banking and Trust Company (BB&T), Deutsche Bank Securities, Inc., SunTrust Bank, and Wells Fargo Bank, N.A., as Co-Syndication Agents, and the lenders party thereto (the “Credit Agreement”), which provides for a $700,000,000 five-year senior unsecured revolving facility (the “Revolving Facility”). Borrowings under the Revolving Facility bear interest, at the Company’s option, at rates based upon LIBOR or a base rate, plus, for each rate, a margin determined in accordance with a ratings-based pricing grid.

The Credit Agreement requires the Company’s ratio of consolidated net debt-to-consolidated earnings before interest, taxes, depreciation, depletion and amortization (EBITDA), as defined, for the trailing-twelve months (the “Ratio”) to not exceed 3.50x as of the end of any fiscal quarter, provided that the Company may exclude from the Ratio debt incurred in connection with certain acquisitions during the quarter or three preceding quarters so long as the Ratio calculated without such exclusion does not exceed 3.75x. Additionally, if no amounts are outstanding under both the Revolving Facility and the trade receivable securitization facility (discussed later), consolidated debt, including debt for which the Company is a co-borrower (see Note O), may be reduced by the Company’s unrestricted cash and cash equivalents in excess of $50,000,000, such reduction not to exceed $200,000,000, for purposes of the covenant calculation. The Company was in compliance with the Ratio at December 31, 2018.

On December 20, 2018, the Company extended its Revolving Facility by one year. The Revolving Facility expires on December 5, 2023, with any outstanding principal amounts, together with interest accrued thereon, due in full on that date. Available borrowings under the Revolving Facility are reduced by any outstanding letters of credit issued by the Company under the Revolving Facility. At December 31, 2018 and 2017, the Company had $2,301,000 of outstanding letters of credit issued under the Revolving Facility and $697,699,000 available for borrowing under the Revolving Facility. The Company paid the bank group an upfront loan commitment fee that is being amortized over the life of the Revolving Facility. The Revolving Facility includes an annual facility fee.

The Company, through a wholly-owned special-purpose subsidiary, has a $400,000,000 trade receivable securitization facility (the “Trade Receivable Facility”). On September 25, 2018, the Company extended the maturity to September 25, 2019. The Trade Receivable Facility, with SunTrust Bank, Regions Bank, PNC Bank, N.A., The Bank of Tokyo-Mitsubishi UFJ, Ltd., New York Branch, and certain other lenders that may become a party to the facility from time to time, is backed by eligible trade receivables, as defined. Borrowings are limited to the lesser of the facility limit or the borrowing base, as defined. These receivables are originated by the Company and then sold or contributed to the wholly-owned special-purpose subsidiary. The Company continues to be responsible for the servicing and administration of the receivables purchased by the wholly-owned special-purpose subsidiary. Borrowings under the Trade Receivable Facility bear interest at a rate equal to one-month LIBOR plus 0.725%, subject to change in the event that this rate no longer reflects the lender’s cost of lending. The Trade Receivable Facility contains a cross-default provision to the Company’s other debt agreements.

The Company’s long-term debt maturities for the five years following December 31, 2018, and thereafter are:

(add 000)
2019	$	390,042
2020		299,015
2021		65
2022		90
2023		299,260
Thereafter		2,132,009
Total	$	3,120,481

The 2019 Floating Rate Notes mature December 20, 2019. The Company has classified these obligations as noncurrent long-term debt on the consolidated balance sheets as of December 31, 2018 as it has the ability and intent to refinance the notes on a long-term basis. For the debt maturity schedule, the 2019 Floating Rate Notes are included in 2023.

The Company has a $5,000,000 short-term line of credit. No amounts were outstanding under this line of credit at December 31, 2018 or 2017.

Accumulated other comprehensive loss includes the unamortized value of terminated forward starting interest rate swap agreements. For the years ended December 31, 2018, 2017 and 2016, the Company recognized $458,000, $1,443,000 and $1,367,000, respectively, as additional interest expense.

Financial Instruments

12 Months Ended

Dec. 31, 2018

Financial Instruments Disclosure [Abstract]

Financial Instruments

Note I: Financial Instruments

The Company’s financial instruments include temporary cash investments, accounts receivable, notes receivable, accounts payable, publicly-registered long-term notes, debentures and other long-term debt.

Temporary cash investments are placed primarily in money market funds, money market demand deposit accounts or offshore time deposit accounts with financial institutions. The Company’s cash equivalents have maturities of less than three months. Due to the short maturity of these investments, they are carried on the consolidated balance sheets at cost, which approximates fair value.

Accounts receivable are due from a large number of customers, primarily in the construction industry, and are dispersed across wide geographic and economic regions. However, accounts receivable are more heavily concentrated in certain states, namely Texas, Colorado, North Carolina, Georgia and Iowa. The estimated fair values of accounts receivable approximate their carrying amounts.

Notes receivable are primarily promissory notes with customers and are not publicly traded. Management estimates that the fair value of notes receivable approximates its carrying amount.

Accounts payable represent amounts owed to suppliers and vendors. The estimated fair value of accounts payable approximates its carrying amount due to the short-term nature of the payables.

The carrying values and fair values of the Company’s long-term debt were $3,120,481,000 and $3,012,224,000, respectively, at December 31, 2018 and $3,027,203,000 and $3,144,902,000, respectively, at December 31, 2017. The estimated fair value of the Company’s publicly-registered long-term debt was estimated based on Level 2 of the fair value hierarchy using quoted market prices. The estimated fair values of other borrowings, which primarily represent variable-rate debt, approximate their carrying amounts as the interest rates reset periodically.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

Note J: Income Taxes

The components of the Company’s income tax expense (benefit) are as follows:

years ended December 31 (add 000)	2018			2017			2016
Federal income taxes:
Current	$	15,285		$	129,236		$	97,975
Deferred		69,599			(239,304	)		68,899
Total federal income taxes		84,884			(110,068	)		166,874
State income taxes:
Current		5,986			14,843			15,189
Deferred		14,134			(882	)		(1,149	)
Total state income taxes		20,120			13,961			14,040
Foreign income taxes:
Current		(1,354	)		1,175			1,064
Deferred		2,055			475			(394	)
Total foreign income taxes		701			1,650			670
Income tax expense (benefit)	$	105,705		$	(94,457	)	$	181,584

On December 22, 2017, the U.S. government enacted the Tax Cuts and Jobs Act of 2017 (the “2017 Tax Act”). The 2017 Tax Act included provisions that lowered the federal statutory corporate income tax rate from 35% to 21% beginning in 2018, imposed a one-time transition tax on mandatory deemed repatriation of undistributed net earnings and changed how foreign earnings are subject to U.S. tax. U.S. GAAP generally requires the effects of a tax law change to be recorded as a component of income tax expense in the period of enactment. However, the SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), which allowed companies to record provisional amounts during a measurement period of up to one year from enactment where the necessary information was not available to complete the accounting for certain income tax effects of the 2017 Tax Act.

The Company recognized, on a provisional basis, a net tax benefit of $258,103,000 related to the 2017 Tax Act for the remeasurement of deferred tax assets and liabilities in its consolidated financial statements for the year ended December 31, 2017. In accordance with the provisions of SAB 118, the Company completed the accounting for the impact of the 2017 Tax Act during the year ended December 31, 2018, and as a result recognized income tax expense of $1,147,000 for the transition tax on mandatory deemed repatriation of undistributed foreign earnings; income tax expense of $1,481,000 for the write off of deferred tax assets that will not be realized due to changes in the deductibility of executive compensation; and an income tax benefit of $21,514,000 primarily related to the accelerated deductions for pension funding, inventory and insurance prepayments that were claimed on the Company’s 2017 income tax returns.

Effective January 1, 2018, global intangible low-taxed income (GILTI) earned by controlled foreign corporations must be included in the income of the U.S. shareholder. Under U.S. GAAP, an accounting policy choice is required to either (1) treat taxes due on future U.S. inclusions related to GILTI as a current period expense when incurred or (2) factor such amounts into a company’s measurement of its deferred taxes. The Company has elected to treat GILTI as a current period expense.

For the years ended December 31, 2018 and 2016, the benefit related to the utilization of federal net operating loss (NOL) carryforwards, reflected in current tax expense, was $5,794,000 and $11,852,000, respectively.

For the year ended December 31, 2016, excess tax benefits attributable to stock-based compensation transactions that were recorded to shareholders’ equity amounted to $6,792,000.

For the years ended December 31, 2018, 2017 and 2016, foreign pretax earnings were $5,718,000, $10,566,000 and $3,865,000, respectively.

The Company’s effective income tax rate varied from the statutory United States income tax rate because of the following tax differences:

years ended December 31	2018			2017			2016
Statutory income tax rate		21.0	%		35.0	%		35.0	%
(Reduction) increase resulting from:
Impact from 2017 Tax Act		(3.3	)		(41.7	)		—
Effect of statutory depletion		(3.4	)		(5.6	)		(5.4	)
State income taxes, net of federal tax benefit		2.8			1.5			1.5
Stock based compensation		(0.5	)		(1.0	)		(0.1	)
Domestic production deduction		—			(2.2	)		(2.0	)
Other items		1.7			(1.3	)		0.9
Effective income tax rate		18.3	%	(15.3%)				29.9	%

The change in the effective income tax rate in 2017 and the lower effective income tax rate in 2018, as compared with 2016, is attributable to the impact of the 2017 Tax Act. The statutory depletion deduction for all years is calculated as a percentage of sales, subject to certain limitations. Due to these limitations, the impact of changes in the sales volumes and earnings may not proportionately affect the Company’s statutory depletion deduction and the corresponding impact on the effective income tax rate.

The Company was entitled to receive a 9% tax deduction related to income from domestic (i.e., United States) production activities in 2017 and 2016. The deduction reduced income tax expense and increased consolidated net earnings by $15,461,000, or $0.25 per diluted share, in 2017 and $13,583,000, or $0.21 per diluted share, in 2016. The domestic production deduction was eliminated by the 2017 Tax Act and will not generate a tax benefit in 2018 and beyond.

The principal components of the Company’s deferred tax assets and liabilities are as follows:

December 31	Deferred Assets (Liabilities)
(add 000)	2018			2017
Deferred tax assets related to:
Employee benefits	$	-		$	16,059
Inventories		52,618			56,242
Valuation and other reserves		22,359			22,989
Net operating loss carryforwards		10,990			11,780
Accumulated other comprehensive loss		84,207			80,116
Other items, net		3,052			3,963
Gross deferred tax assets		173,226			191,149
Valuation allowance on deferred tax assets		(8,604	)		(10,349	)
Total net deferred tax assets		164,622			180,800
Deferred tax liabilities related to:
Property, plant and equipment		(478,329	)		(407,400	)
Partnerships and joint ventures		(204,315	)		(15,617	)
Goodwill and other intangibles		(170,538	)		(168,506	)
Employee benefits		(17,004	)		-
Total deferred tax liabilities		(870,186	)		(591,523	)
Deferred income taxes, net	$	(705,564	)	$	(410,723	)

The Company had $3,219,000 of domestic federal NOL carryforwards at December 31, 2018. The Company had domestic state NOL carryforwards of $168,060,000 and $197,916,000 at December 31, 2018 and 2017, respectively. These carryforwards have various expiration dates through 2037. At December 31, 2018 and 2017, deferred tax assets associated with these carryforwards were $10,990,000 and $11,780,000, respectively, net of the federal benefit of the state deduction, for which valuation allowances of $8,576,000 and $10,085,000, respectively, were recorded. The Company also had domestic tax credit carryforwards of $993,000 and $1,342,000 at December 31, 2018 and 2017, respectively, which expire in 2036. At December 31, 2018 and 2017, deferred tax assets associated with these carryforwards were $784,000 and $1,060,000, respectively, net of the federal benefit of the state deduction, for which valuation allowances of $28,000 and $264,000, respectively, were recorded.

Deferred tax liabilities for property, plant and equipment result from accelerated depreciation methods being used for income tax purposes as compared with the straight-line method for financial reporting purposes.

Deferred tax liabilities for partnerships and joint ventures relate to the difference between the tax basis in partnerships and joint ventures when compared to the basis for financial reporting purposes. The increase in 2018 was a result of the Bluegrass acquisition, as this business is a partnership for income tax purposes.

Deferred tax liabilities related to goodwill and other intangibles reflect the cessation of goodwill amortization for financial reporting purposes, while amortization continues for income tax purposes.

The change in deferred taxes for employee benefits was primarily driven by the additional pension funding in 2018 for the 2017 plan year.

The Company expects to permanently reinvest the earnings from its wholly-owned Canadian and Bahamian subsidiaries, and accordingly, has not provided deferred taxes on the subsidiaries’ undistributed net earnings or basis differences. The Company believes that the tax liability that would be incurred upon repatriation is immaterial at December 31, 2018.

The following table summarizes the Company’s unrecognized tax benefits, excluding interest and correlative effects:

years ended December 31 (add 000)	2018			2017			2016
Unrecognized tax benefits at beginning of year	$	22,367		$	21,807		$	18,727
Gross increases – tax positions in prior years		944			1,396			2,401
Gross decreases – tax positions in prior years		-			(672	)		(1,924	)
Gross increases – tax positions in current year		1,802			4,961			4,650
Gross decreases – tax positions in current year		(1,013	)		(946	)		(2,047	)
Lapse of statute of limitations		—			(4,179	)		—
Unrecognized tax benefits at end of year	$	24,100		$	22,367		$	21,807

Amount that, if recognized, would favorably impact the effective tax rate	$	12,820		$	10,399		$	11,603

Unrecognized tax benefits are reversed as a discrete event if an examination of applicable tax returns is not initiated by a federal or state tax authority within the statute of limitations or upon effective settlement with federal or state tax authorities. Management believes its accrual for unrecognized tax benefits is sufficient to cover uncertain tax positions reviewed during audits by taxing authorities. The accrual is not expected to materially change in the next twelve months.

For the year ended December 31, 2017, $3,922,000 was reversed into income upon the statute of limitations expiration for the 2010 through 2013 tax years.

The Company’s tax years subject to federal, state or foreign examinations are 2011 through 2018.

Retirement Plans, Postretirement and Postemployment Benefits

12 Months Ended

Dec. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Retirement Plans, Postretirement and Postemployment Benefits

Note K: Retirement Plans, Postretirement and Postemployment Benefits

The Company sponsors defined benefit retirement plans that cover substantially all employees. Additionally, the Company provides other postretirement benefits for certain employees, including medical benefits for retirees and their spouses and retiree life insurance. Employees starting on or after January 1, 2002 are not eligible for postretirement welfare plans. The Company also provides certain benefits, such as disability benefits, to former or inactive employees after employment but before retirement.

The measurement date for the Company’s defined benefit plans, postretirement benefit plans and postemployment benefit plans is December 31.

Defined Benefit Retirement Plans. Retirement plan assets are invested in listed stocks, bonds, hedge funds, real estate and cash equivalents. Defined retirement benefits for salaried employees are based on each employee’s years of service and average compensation for a specified period of time before retirement. Defined retirement benefits for hourly employees are generally stated amounts for specified periods of service.

The Company sponsors a Supplemental Excess Retirement Plan (SERP) that generally provides for the payment of retirement benefits in excess of allowable Internal Revenue Code limits. The SERP generally provides for a lump-sum payment of vested benefits. When these benefit payments exceed the sum of the service and interest costs for the SERP during a year, the Company recognizes a pro-rata portion of the SERP’s unrecognized actuarial loss as settlement expense.

The net periodic retirement benefit cost of defined benefit plans includes the following components:

years ended December 31 (add 000)	2018			2017			2016
Service cost	$	31,624		$	26,805		$	22,167
Interest cost		33,209			36,101			35,879
Expected return on assets		(46,011	)		(39,759	)		(37,699	)
Amortization of:
Prior service cost		104			311			350
Actuarial loss		12,830			14,138			12,074
Transition asset		(1	)		(1	)		(1	)
Settlement charge		2,936			21			124
Termination benefit charge		—			—			764
Net periodic benefit cost	$	34,691		$	37,616		$	33,658

The components of net periodic benefit cost other than service cost are included in the line item Other nonoperating (income) and expenses, net, in the consolidated statements of earnings.

The expected return on assets is calculated by applying an annually selected expected rate of return assumption to the estimated fair value of the plan assets, giving consideration to contributions and benefits paid. The termination benefit charge represents the increased benefits payable to former Texas Industries, Inc. (TXI) executives as part of their change-in-control agreements.

The Company recognized the following amounts in consolidated comprehensive earnings:

years ended December 31

(add 000)	2018			2017			2016
Actuarial loss	$	32,214		$	13,343		$	52,028
Net prior service cost		3			—			—
Amortization of:
Prior service cost		(104	)		(311	)		(350	)
Actuarial loss		(12,830	)		(14,138	)		(12,074	)
Transition asset		1			1			1
Special plan termination benefits		—			—			(764	)
Settlement charge		(2,936	)		(21	)		(124	)
Total	$	16,348		$	(1,126	)	$	38,717

Accumulated other comprehensive loss includes the following amounts that have not yet been recognized in net periodic benefit cost:

December 31	2018						2017
(add 000)	Gross			Net of tax			Gross			Net of tax
Prior service cost	$	14		$	9		$	115		$	71
Actuarial loss		233,688			146,588			217,240			134,066
Transition asset		(5	)		(3	)		(6	)		(4	)
Total	$	233,697		$	146,594		$	217,349		$	134,133

The prior service cost, actuarial loss and transition asset expected to be recognized in net periodic benefit cost during 2019 are $8,000 (net of deferred taxes of $2,000), $15,727,000 (net of deferred taxes of $3,893,000) and $1,000, respectively. These amounts are included in accumulated other comprehensive loss at December 31, 2018.

The defined benefit plans’ change in projected benefit obligation is as follows:

years ended December 31

(add 000)	2018			2017
Net projected benefit obligation at beginning of year	$	879,335		$	831,849
Service cost		31,624			26,805
Interest cost		33,209			36,101
Actuarial (gain) loss		(54,621	)		56,675
Plan amendment		3			-
Gross benefits paid		(41,654	)		(72,095	)
Net projected benefit obligation at end of year	$	847,896		$	879,335

The Company’s change in plan assets, funded status and amounts recognized on the Company’s consolidated balance sheets are as follows:

years ended December 31

(add 000)	2018			2017
Change in plan assets:
Fair value of plan assets at beginning of year	$	638,106		$	596,207
Actual return on plan assets, net		(40,823	)		83,091
Employer contributions		162,281			30,903
Gross benefits paid		(41,654	)		(72,095	)
Fair value of plan assets at end of year	$	717,910		$	638,106

December 31

(add 000)	2018			2017
Funded status of the plan at end of year	$	(129,986	)	$	(241,229	)
Accrued benefit cost	$	(129,986	)	$	(241,229	)

December 31

(add 000)	2018			2017
Amounts recognized on consolidated balance sheets consist of:
Current liability	$	(8,992	)	$	(11,092	)
Noncurrent liability		(120,994	)		(230,137	)
Net amount recognized at end of year	$	(129,986	)	$	(241,229	)

The accumulated benefit obligation for all defined benefit pension plans was $771,921,000 and $792,912,000 at December 31, 2018 and 2017, respectively.

Benefit obligations and fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets are as follows:

December 31

(add 000)	2018		2017
Projected benefit obligation	$	98,729	$	879,335
Accumulated benefit obligation	$	85,548	$	792,912
Fair value of plan assets	$	560	$	638,106

Weighted-average assumptions used to determine benefit obligations as of December 31 are:

	2018	2017
Discount rate	4.38%	3.76%
Rate of increase in future compensation levels	4.50%	4.50%

Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31 are:

	2018	2017	2016
Discount rate	3.76%	4.29%	4.67%
Rate of increase in future compensation levels	4.50%	4.50%	4.50%
Expected long-term rate of return on assets	6.75%	6.75%	7.00%

The expected long-term rate of return on assets is based on a building-block approach, whereby the components are weighted based on the allocation of pension plan assets.

For 2018 and 2017, the Company estimated the remaining lives of participants in the pension plans using the RP-2014 Base Table. The no-collar table was used for salaried participants and the blue-collar table, reflecting the experience of the Company’s participants, was used for hourly participants. The Company used mortality improvement scales MP-2018 and MP-2017 for the years 2018 and 2017, respectively. The change in mortality improvement scale in 2018 did not have a material impact on the projected benefit obligation.

The target allocation for 2018 and the actual pension plan asset allocation by asset class are as follows:

	Percentage of Plan Assets
	2018	December 31
Asset Class	Target Allocation	2018	2017
Equity securities	56%	57%	57%
Debt securities	30%	32%	29%
Hedge funds	4%	6%	7%
Real estate	10%	5%	7%
Total	100%	100%	100%

The Company’s investment strategy is for approximately 45% of equity securities, excluding hedge funds and real estate, to be invested in mid-sized to large capitalization U.S. funds, with the remaining invested in small capitalization, emerging markets and international funds. Debt securities, or fixed income investments, are invested in funds benchmarked to the Barclays U.S. Aggregate Bond Index.

The fair values of pension plan assets by asset class and fair value hierarchy level are as follows:

	Fair Value Measurements
December 31	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Net Asset Value		Total Fair Value
(add 000)	2018
Equity securities¹:
Mid-sized to large cap	$	—	$	—	$	—	$	196,475	$	196,475
Small cap, international and emerging growth funds		—		—		—		210,371		210,371
Debt securities¹:
Core fixed income		—		—		—		228,194		228,194
Real estate		—		—		—		35,553		35,553
Hedge funds		—		—		—		44,453		44,453
Cash equivalents		2,864		—		—		—		2,864
Total	$	2,864	$	—	$	—	$	715,046	$	717,910

	2017
Equity securities¹:
Mid-sized to large cap	$	—	$	—	$	—	$	177,497	$	177,497
Small cap, international and emerging growth funds		—		—		—		186,272		186,272
Debt securities¹:
Core fixed income		—		—		—		182,225		182,225
Real estate		—		—		—		46,467		46,467
Hedge funds		—		—		—		45,604		45,604
Cash equivalents		41		—		—		—		41
Total	$	41	$	—	$	—	$	638,065	$	638,106

¹ These investments are common collective investment trusts valued using the net asset value (NAV) unit price provided by the fund administrator. The NAV is based on the value of the underlying assets owned by the fund.

Real estate investments are stated at estimated fair value, which is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair values of real estate investments generally do not reflect transaction costs which may be incurred upon disposition of the real estate investments and do not necessarily represent the prices at which the real estate investments would be sold or repaid, since market prices of real estate investments can only be determined by negotiation between a willing buyer and seller. An independent valuation consultant is employed to determine the fair value of the real estate investments. The value of hedge funds is based on the values of the sub-fund investments. In determining the fair value of each sub-fund’s investment, the hedge funds’ Board of Trustees uses the values provided by the sub-funds and any other considerations that may, in its judgment, increase or decrease such estimated value.

In 2018 and 2017, the Company made combined pension plan and SERP contributions of $162,281,000 and $30,903,000, respectively. The Company currently estimates that it will contribute $32,022,000 to its pension plans in 2019.

The expected benefit payments to be paid from plan assets for each of the next five years and the five-year period thereafter are as follows:

(add 000)
2019	$	40,835
2020	$	42,908
2021	$	44,237
2022	$	45,848
2023	$	47,170
Years 2024 - 2028	$	260,117

Postretirement Benefits. The net periodic postretirement benefit credit for postretirement plans includes the following components:

years ended December 31

(add 000)	2018			2017			2016
Service cost	$	77		$	80		$	85
Interest cost		519			727			863
Amortization of:
Prior service credit		(2,074	)		(1,741	)		(1,959	)
Actuarial gain		(211	)		(364	)		(499	)
Settlement credit		—			—			(9	)
Total net periodic benefit credit	$	(1,689	)	$	(1,298	)	$	(1,519	)

The components of net periodic benefit credit other than service cost are included in the line item Other nonoperating (income) and expenses, net, in the consolidated statements of earnings.

The Company recognized the following amounts in consolidated comprehensive earnings:

years ended December 31

(add 000)	2018			2017			2016
Actuarial (gain) loss	$	(1,700	)	$	1,236		$	686
Net prior service credit		—			(3,902	)		(1,326	)
Settlement credit		—			—			9
Amortization of:
Prior service credit		2,074			1,741			1,959
Actuarial gain		211			364			499
Total	$	585		$	(561	)	$	1,827

Accumulated other comprehensive loss includes the following amounts that have not yet been recognized in net periodic benefit credit or cost:

December 31	2018						2017
(add 000)	Gross			Net of tax			Gross			Net of tax
Prior service credit	$	(3,747	)	$	(2,388	)	$	(6,314	)	$	(3,899	)
Actuarial gain		(4,238	)		(2,701	)		(2,256	)		(1,393	)
Total	$	(7,985	)	$	(5,089	)	$	(8,570	)	$	(5,292	)

The prior service credit and actuarial gain expected to be recognized in net periodic benefit cost during 2019 is $762,000 (net of deferred taxes of $189,000) and $473,000 (net of deferred taxes of $117,000), respectively, and are included in accumulated other comprehensive loss at December 31, 2018.

The postretirement health care plans’ change in benefit obligation is as follows:

years ended December 31

(add 000)	2018			2017
Change in benefit obligation:
Net benefit obligation at beginning of year	$	15,347		$	20,591
Service cost		77			80
Interest cost		519			727
Participants’ contributions		312			3,421
Actuarial (gain) loss		(1,700	)		1,236
Gross benefits paid		(1,262	)		(6,806	)
Plan amendments		-			(3,902	)
Net benefit obligation at end of year	$	13,293		$	15,347

The postretirement health care plans’ change in plan assets, funded status and amounts recognized on the Company’s consolidated balance sheets are as follows:

years ended December 31

(add 000)	2018			2017
Fair value of plan assets at beginning of year:	$	—		$	—
Employer contributions		950			3,385
Participants’ contributions		312			3,421
Gross benefits paid		(1,262	)		(6,806	)
Fair value of plan assets at end of year	$	—		$	—

December 31

(add 000)	2018			2017
Funded status of the plan at end of year	$	(13,293	)	$	(15,347	)
Accrued benefit cost	$	(13,293	)	$	(15,347	)

December 31

(add 000)	2018			2017
Amounts recognized on consolidated balance sheets consist of:
Current liability	$	(950	)	$	(2,560	)
Noncurrent liability		(12,343	)		(12,787	)
Net amount recognized at end of year	$	(13,293	)	$	(15,347	)

Weighted-average assumptions used to determine the postretirement benefit obligation as of December 31 are:

		2018				2017
Discount rate			4.15	%			3.47	%

Weighted-average assumptions used to determine net postretirement benefit credit for the years ended December 31 are:

		2018				2017							2016
Discount rate			3.47	%				3.78		%					4.25		%

For 2018 and 2017, the Company estimated the remaining lives of participants in the postretirement benefit plans using the RP-2014 Base Table. The no-collar table was used for salaried participants and the blue-collar table, reflecting the experience of the Company’s participants, was used for hourly participants. The Company used mortality improvement scales MP-2018 and MP-2017 for the years 2018 and 2017, respectively. The change in mortality improvement scale in 2018 did not have a material impact on the projected benefit obligation.

Assumed health care cost trend rates at December 31 are:

	2018	2017
Health care cost trend rate assumed for next year	7.0%	7.0%
Rate to which the cost trend rate gradually declines	5.0%	5.0%
Year the rate reaches the ultimate rate	2023	2022

Assumed health care cost trend rates have a significant effect on the amounts reported for the Company’s health care plans. A one percentage-point change in assumed health care cost trend rates would have the following effects:

	One Percentage Point
(add 000)	Increase		(Decrease)
Total service and interest cost components	$	25	$	(22	)
Postretirement benefit obligation	$	640	$	(575	)

The Company estimates that it will contribute $950,000 to its postretirement health care plans in 2019.

The total expected benefit payments to be paid by the Company, net of participant contributions, for each of the next five years and the five-year period thereafter are as follows:

(add 000)
2019	$	950
2020	$	1,492
2021	$	1,419
2022	$	1,344
2023	$	1,254
Years 2024 – 2028	$	5,809

Defined Contribution Plan. The Company maintains a defined contribution plan that covers substantially all employees. This plan, qualified under Section 401(a) of the Internal Revenue Code, is a retirement savings and investment plan for the Company’s salaried and hourly employees. Under certain provisions of the plan, the Company, at established rates, matches employees’ eligible contributions. The Company’s matching obligations were $16,545,000 in 2018, $14,893,000 in 2017 and $13,235,000 in 2016.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

Note L: Stock-Based Compensation

On May 19, 2016, the Company’s shareholders approved the Martin Marietta Amended and Restated Stock-Based Award Plan. The Martin Marietta Materials, Inc. Stock-Based Award Plan, as amended from time to time (along with the Amended Omnibus Securities Award Plan, originally approved in 1994, the “Plans”) is still effective for awards made prior to 2017. The Company has been authorized by the Board of Directors to repurchase shares of the Company’s common stock for issuance under the stock-based award plans (see Note N).

The Company grants restricted stock awards under the Plans to a group of executive officers, key personnel and nonemployee members of the Board of Directors. The vesting of certain restricted stock awards is based on certain performance criteria over a specified period of time. The number of shares may be increased to the maximum or reduced to the minimum threshold based on the results of those criteria. In addition, certain awards are granted to individuals to encourage retention and motivate key employees. These awards generally vest if the employee is continuously employed over a specified period of time and require no payment from the employee. Awards granted to nonemployee members of the Board of Directors vest immediately.

The fair value of stock-based award grants is amortized to expense over the vesting period. Awards to employees eligible for retirement prior to the award becoming fully vested are amortized to expense over the period through the date that the employee first becomes eligible to retire and is no longer required to provide service to earn the award. Awards granted to nonemployee members of the Board of Directors are expensed immediately.

Additionally, an incentive compensation stock plan has been adopted under the Plans whereby certain participants may elect to use up to 50% of their annual incentive compensation to acquire units representing shares of the Company’s common stock at a 20% discount to the market value on the date of the incentive compensation award. Certain executive officers are required to participate in the incentive compensation stock plan at certain minimum levels. Participants receive unrestricted shares of common stock in an amount equal to their respective units generally at the end of a 34-month period of additional employment from the date of award or at retirement beginning at age 62. All rights of ownership of the common stock convey to the participants upon the issuance of their respective shares at the end of the ownership-vesting period.

The following table summarizes information for restricted stock awards and incentive compensation stock awards for 2018:

	Restricted Stock - Service Based					Restricted Stock - Performance Based					Incentive Compensation Stock
	Number of Awards			Weighted- Average Grant-Date Fair Value		Number of Awards			Weighted- Average Grant-Date Fair Value		Number of Awards			Weighted- Average Grant-Date Fair Value
January 1, 2018		314,840		$	151.84		139,999		$	150.34		38,510		$	166.67
Awarded		64,352		$	211.03		37,138		$	212.12		18,180		$	212.12
Distributed		(88,674	)	$	159.04		(20,219	)	$	126.01		(20,992	)	$	138.54
Forfeited		(12,371	)	$	211.63		(4,979	)	$	182.90		(322	)	$	184.74
December 31, 2018		278,147		$	158.29		151,939		$	174.74		35,376		$	206.55

The weighted-average grant-date fair value of service-based restricted stock awards granted during 2018, 2017 and 2016 was $211.03, $213.76 and $128.48, respectively. The weighted-average grant-date fair value of performance-based restricted stock awards granted during 2018, 2017 and 2016 was $212.12, $207.73 and $124.41, respectively. The weighted-average grant-date fair value of incentive compensation stock awards granted during 2018, 2017 and 2016 was $212.12, $208.68 and $124.41, respectively.

The aggregate intrinsic values for unvested restricted stock awards and unvested incentive compensation stock awards at December 31, 2018 were $73,919,000 and $234,000, respectively, and were based on the closing price of the Company’s common stock at December 31, 2018, which was $171.87. The aggregate intrinsic values of restricted stock awards distributed during the years ended December 31, 2018, 2017 and 2016 were $22,985,000, $15,771,000 and $9,738,000, respectively. The aggregate intrinsic values of incentive compensation stock awards distributed during the years ended December 31, 2018, 2017 and 2016 were $1,662,000, $2,601,000 and $1,941,000, respectively. The aggregate intrinsic values for distributed awards were based on the closing prices of the Company’s common stock on the dates of distribution.

Under the Plans, prior to 2016, the Company granted options to employees to purchase its common stock at a price equal to the closing market value at the date of grant. Options become exercisable in four annual installments beginning one year after date of grant. Options granted starting in 2013 expire ten years after the grant date while outstanding options granted prior to 2013 expire eight years after the grant date.

In connection with the TXI acquisition, completed in 2014, the Company issued 821,282 Martin Marietta stock options (Replacement Options) to holders of outstanding TXI stock options at the acquisition date. The Company issued 0.7 Replacement Options for each outstanding TXI stock option, and the Replacement Option prices reflected the exchange ratio. The Replacement Options will expire on the original contractual dates when the TXI stock options were initially issued. Consistent with the terms of the Company’s other outstanding stock options, Replacement Options expire 90 days after employment is terminated.

The following table includes summary information for stock options as of December 31, 2018:

	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Life (years)
Outstanding at January 1, 2018		301,958		$	91.44
Exercised		(89,557	)	$	81.06
Terminated		(2,011	)	$	83.32
Outstanding at December 31, 2018		210,390		$	95.93		3.6

Exercisable at December 31, 2018		197,241		$	92.02		3.4

The aggregate intrinsic values of options exercised during the years ended December 31, 2018, 2017 and 2016 were $12,395,000, $13,247,000 and $22,571,000, respectively, and were based on the closing prices of the Company’s common stock on the dates of exercise. The aggregate intrinsic values for options outstanding and exercisable at December 31, 2018 were $15,977,000 and $15,750,000, respectively, and were based on the closing price of the Company’s common stock at December 31, 2018, which was $171.87. The excess tax benefits for stock options exercised during the years ended December 31, 2018, 2017 and 2016 were $1,741,000, $3,483,000 and $4,238,000, respectively.

At December 31, 2018, there are approximately 792,000 awards available for grant under the Plans. In 2016, the Company’s shareholders approved the issuance of an additional 800,000 shares of common stock under the Plans. As part of approving the shares, the Company agreed to not issue any additional awards under the legacy TXI plan. The awards available for grant under the Plans at December 31, 2018 reflect no awards available under the legacy TXI plan.

In 1996, the Company adopted the Shareholder Value Achievement Plan to award shares of the Company’s common stock to key senior employees based on certain common stock performance criteria over a long-term period. Under the terms of this plan, 250,000 shares of common stock were reserved for issuance. Through December 31, 2018, 42,025 shares have been issued under this plan. No awards have been granted under this plan since 2000.

The Company adopted and the shareholders approved the Common Stock Purchase Plan for Directors in 1996, which provides nonemployee members of the Board of Directors the election to receive all or a portion of their total fees in the form of the Company’s common stock. Beginning in 2016, members of the Board of Directors were not required to defer any of their fees in the form of the Company’s common stock. Under the terms of this plan, 300,000 shares of common stock were reserved for issuance. Nonemployee members of the Board of Directors elected to defer portions of their fees representing 3,105, 2,132 and 3,699 shares of the Company’s common stock under this plan during 2018, 2017 and 2016, respectively.

The following table summarizes stock-based compensation expense for the years ended December 31, 2018, 2017 and 2016, unrecognized compensation cost for nonvested awards at December 31, 2018 and the weighted-average period over which unrecognized compensation cost will be recognized:

(add 000, except year data)	Stock Options		Restricted Stock		Incentive Compensation Stock		Directors’ Awards		Total
Stock-based compensation expense recognized for years ended December 31:
2018	$	242	$	27,650	$	729	$	632	$	29,253
2017	$	684	$	28,657	$	661	$	458	$	30,460
2016	$	1,646	$	17,747	$	442	$	646	$	20,481
Unrecognized compensation cost at December 31, 2018:	$	50	$	21,992	$	495	$	—	$	22,537
Weighted-average period over which unrecognized compensation cost will be recognized:	0.4 years		1.6 years		1.6 years

The following presents expected stock-based compensation expense in future periods for outstanding awards as of December 31, 2018:

(add 000)
2019	$	16,191
2020		5,843
2021		409
2022		94
Total	$	22,537

Stock-based compensation expense is included in selling, general and administrative expenses in the Company’s consolidated statements of earnings.

Leases

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Leases

Note M: Leases

Total lease expense for operating leases was $122,545,000, $90,731,000 and $85,945,000 for the years ended December 31, 2018, 2017 and 2016, respectively. The Company’s operating leases generally contain renewal and/or purchase options with varying terms. The Company has royalty agreements that generally require royalty payments based on tons produced or total sales dollars and also contain minimum payments. Total royalties, principally for leased properties, were $52,482,000, $51,827,000 and $55,257,000 for the years ended December 31, 2018, 2017 and 2016, respectively. The Company also has capital lease obligations for machinery and equipment.

Future minimum lease and royalty commitments for all noncancelable agreements and capital lease obligations as of December 31, 2018 are as follows:

(add 000)	Capital Leases			Operating Leases		Royalty Commitments
2019	$	3,718		$	105,955	$	14,614
2020		2,695			70,478		11,364
2021		1,735			60,382		10,335
2022		1,004			57,531		9,545
2023		713			56,511		8,109
Thereafter		3,893			318,147		65,981
Total		13,758		$	669,004	$	119,948
Less: imputed interest		(2,879	)
Present value of minimum lease payments		10,879
Less: current capital lease obligations		(3,249	)
Long-term capital lease obligations	$	7,630

Of the total future minimum commitments, $172,877,000 relates to the Company’s contracts of affreightment.

Shareholders' Equity

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Shareholders' Equity

Note N: Shareholders’ Equity

The authorized capital structure of the Company includes 100,000,000 shares of common stock, with a par value of $0.01 a share. At December 31, 2018, approximately 1,819,000 common shares were reserved for issuance under stock-based award plans.

Pursuant to authority granted by its Board of Directors, the Company can repurchase up to 20,000,000 shares of common stock. The Company repurchased 521,140, 457,742 and 1,587,987 shares of common stock during 2018, 2017 and 2016, respectively. At December 31, 2018, 14,147,751 shares of common stock were remaining under the Company’s repurchase authorization.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note O: Commitments and Contingencies

Legal and Administrative Proceedings. The Company is engaged in certain legal and administrative proceedings incidental to its normal business activities. In the opinion of management and counsel, based upon currently-available facts, it is remote that the ultimate outcome of any litigation and other proceedings, including those pertaining to environmental matters (see Note A), relating to the Company and its subsidiaries, will have a material adverse effect on the overall results of the Company’s operations, its cash flows or its financial position.

Asset Retirement Obligations. The Company incurs reclamation and teardown costs as part of its mining and production processes. Estimated future obligations are discounted to their present value and accreted to their projected future obligations via charges to operating expenses. Additionally, the fixed assets recorded concurrently with the liabilities are depreciated over the period until retirement activities are expected to occur. Total accretion and depreciation expenses for 2018, 2017 and 2016 were $8,015,000, $8,682,000 and $8,823,000, respectively, and are included in Other operating income and expenses, net, in the consolidated statements of earnings.

The following shows the changes in the asset retirement obligations:

years ended December 31:

(add 000)	2018			2017
Balance at beginning of year	$	109,653		$	101,106
Accretion expense		5,074			4,768
Liabilities incurred and liabilities assumed in business combinations		4,692			7,940
Liabilities settled		(2,821	)		(309	)
Revisions in estimated cash flows		5,206			(3,852	)
Balance at end of year	$	121,804		$	109,653

Other Environmental Matters. The Company’s operations are subject to and affected by federal, state and local laws and regulations relating to the environment, health and safety and other regulatory matters. Certain of the Company’s operations may, from time to time, involve the use of substances that are classified as toxic or hazardous within the meaning of these laws and regulations. Environmental operating permits are, or may be, required for certain of the Company’s operations, and such permits are subject to modification, renewal and revocation. The Company regularly monitors and reviews its operations, procedures and policies for compliance with these laws and regulations. Despite these compliance efforts, risk of environmental remediation liability is inherent in the operation of the Company’s businesses, as it is with other companies engaged in similar businesses. The Company has no material provisions for environmental remediation liabilities and does not believe such liabilities will have a material adverse effect on the Company in the future.

Insurance Reserves. The Company has insurance coverage with large deductibles for workers’ compensation, automobile liability, marine liability and general liability claims. The Company is also self-insured for health claims. At December 31, 2018 and 2017, reserves of $48,256,000 and $48,061,000, respectively, were recorded for all such insurance claims. The Company records the reserves based on an actuarial-determined analysis, which calculates development factors that are applied to total case reserves within the insurance programs. While the Company believes the assumptions used to calculate these liabilities are appropriate, significant differences in actual experience and/or significant changes in these assumptions may materially affect insurance costs.

Letters of Credit. In the normal course of business, the Company provides certain third parties with standby letter of credit agreements guaranteeing its payment for certain insurance claims, contract performance and permit requirements. At December 31, 2018, the Company was contingently liable for $36,081,000 in letters of credit, of which $2,301,000 were issued under the Company’s Revolving Facility.

Surety Bonds. In the normal course of business, at December 31, 2018, the Company was contingently liable for $375,561,000 in surety bonds required by certain states and municipalities and their related agencies. The bonds are principally for certain insurance claims, construction contracts, reclamation obligations and mining permits guaranteeing the Company’s own performance. Five of these bonds total $77,603,000, or 21%, of all outstanding surety bonds. The Company has indemnified the underwriting insurance companies, Liberty Mutual and W.R. Berkley, against any exposure under the surety bonds. In the Company’s past experience, no material claims have been made against these financial instruments.

Borrowing Arrangements with Affiliate. The Company is a co-borrower with an unconsolidated affiliate for a revolving line of credit agreement with BB&T, of which $12,710,000 was outstanding as of December 31, 2018. The line of credit was amended in January 2018 to extend the maturity to March 2020 and reduce the line of credit from $25,000,000 to $15,500,000. The affiliate has agreed to reimburse and indemnify the Company for any payments and expenses the Company may incur from this agreement. The Company holds a lien on the affiliate’s membership interest in a joint venture as collateral for payment under the revolving line of credit.

In 2014, the Company loaned the unconsolidated affiliate a total of $6,000,000 as an interest-only note due December 31, 2022.

Purchase Commitments. The Company had purchase commitments for property, plant and equipment of $118,664,000 as of December 31, 2018. The Company also had other purchase obligations related to energy and service contracts of $106,360,000 as of December 31, 2018. The Company’s contractual purchase commitments as of December 31, 2018 are as follows:

(add 000)

2019	$	181,768
2020		14,177
2021		6,264
2022		3,689
2023		1,931
Thereafter		17,195
Total	$	225,024

Capital expenditures in 2018, 2017 and 2016 that were purchase commitments as of the prior year end were $79,345,000, $83,748,000 and $62,927,000, respectively.

Employees. Approximately 11% of the Company’s employees are represented by a labor union. All such employees are hourly employees. The Company maintains collective bargaining agreements relating to the union employees within the Building Materials business and Magnesia Specialties segment. Of the Magnesia Specialties segment, located in Manistee, Michigan and Woodville, Ohio, 100% of its hourly employees are represented by labor unions. The Manistee collective bargaining agreement expires in August 2019. The Woodville collective bargaining agreement expires in June 2022.

Segments

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Segments

Note P: Segments

The Building Materials business is comprised of divisions which represent operating segments. Certain divisions are consolidated into reportable segments for financial reporting purposes as they meet the aggregation criteria. The Building Materials business contains three reportable segments: Mid-America Group, Southeast Group and West Group. The Magnesia Specialties business represents an individual operating and reportable segment. The accounting policies used for segment reporting are the same as those described in Note A.

The Company’s evaluation of performance and allocation of resources are based primarily on earnings from operations. Consolidated earnings from operations include total revenues less cost of revenues; selling, general and administrative expenses; acquisition-related expenses, net; other operating income and expenses, net; and exclude interest expense; other nonoperating income, net; and income tax expense (benefit). Corporate loss from operations primarily includes depreciation on capitalized interest; expenses for corporate administrative functions; acquisition-related expenses, net; and other nonrecurring and/or non-operational income and expenses excluded from the Company’s evaluation of segment performance and resource allocation. All long-term debt and related interest expense are held at Corporate.

Assets employed by segment include assets directly identified with those operations. Corporate assets consist primarily of cash and cash equivalents; property, plant and equipment for corporate operations; investments and other assets not directly identifiable with a reportable segment.

The following tables display selected financial data for the Company’s reportable segments. The acquired Bluegrass operations are located in the Mid-America Group and Southeast Group. Total revenues, as well as the consolidated statements of earnings and comprehensive earnings, exclude intersegment revenues which represent sales from one segment to another segment, which are eliminated. Prior-year information has been reclassified to conform to current year revenue presentation.

years ended December 31 (add 000) Total revenues	2018		2017		2016
Mid-America Group	$	1,223,236	$	1,053,326	$	1,017,098
Southeast Group		423,382		362,555		321,078
West Group		2,309,924		2,279,723		2,223,515
Total Building Materials Business		3,956,542		3,695,604		3,561,691
Magnesia Specialties		287,723		269,990		257,058
Total	$	4,244,265	$	3,965,594	$	3,818,749

Gross profit (loss)
Mid-America Group	$	366,918	$	335,394	$	306,560
Southeast Group		77,193		74,642		57,286
West Group		416,212		465,596		466,790
Total Building Materials Business		860,323		875,632		830,636
Magnesia Specialties		98,682		89,398		89,603
Corporate		7,572		6,910		(8,501	)
Total	$	966,577	$	971,940	$	911,738

Selling, general and administrative expenses
Mid-America Group	$	55,775	$	53,937	$	52,712
Southeast Group		18,727		17,144		17,245
West Group		107,613		102,650		95,631
Total Building Materials Business		182,115		173,731		165,588
Magnesia Specialties		9,999		9,537		9,617
Corporate		88,440		78,860		66,401
Total	$	280,554	$	262,128	$	241,606

Earnings (Loss) from operations
Mid-America Group	$	319,139		$	284,789		$	258,422
Southeast Group		75,840			61,238			41,653
West Group		295,801			360,544			379,417
Total Building Materials Business		690,780			706,571			679,492
Magnesia Specialties		88,063			79,431			79,306
Corporate		(88,106	)		(85,621	)		(81,532	)
Total	$	690,737		$	700,381		$	677,266

Earnings from operations for the West Group for 2018 reflect asset and portfolio rationalization impairment charges of $18,838,000.

(add 000) Depreciation, depletion and amortization	2018		2017		2016
Mid-America Group	$	93,639	$	69,691	$	64,295
Southeast Group		41,214		30,780		30,590
West Group		180,870		169,853		164,653
Total Building Materials Business		315,723		270,324		259,538
Magnesia Specialties		10,413		10,070		10,354
Corporate		17,897		16,768		15,361
Total	$	344,033	$	297,162	$	285,253

December 31 (add 000) Assets employed	2018		2017		2016
Mid-America Group	$	2,788,454	$	1,532,867	$	1,406,526
Southeast Group		1,299,469		616,344		594,967
West Group		4,989,639		5,014,231		4,904,018
Total Building Materials Business		9,077,562		7,163,442		6,905,511
Magnesia Specialties		156,106		152,257		150,969
Corporate		317,751		1,676,812		244,425
Total	$	9,551,419	$	8,992,511	$	7,300,905

Total property additions, including the impact of acquisitions
Mid-America Group	$	1,157,073	$	139,505	$	152,014
Southeast Group		603,078		34,636		30,588
West Group		148,164		240,793		338,795
Total Building Materials Business		1,908,315		414,934		521,397
Magnesia Specialties		12,450		11,129		8,944
Corporate		4,838		12,558		10,430
Total	$	1,925,603	$	438,621	$	540,771

Property additions through acquisitions
Mid-America Group	$	980,236	$	60	$	1,524
Southeast Group		561,503		—		—
West Group		1,421		2,420		132,112
Total Building Materials Business		1,543,160		2,480		133,636
Magnesia Specialties		—		—		—
Corporate		—		—		—
Total	$	1,543,160	$	2,480	$	133,636

Revenues and Gross Profit

12 Months Ended

Dec. 31, 2018

Revenues And Gross Profit [Abstract]

Revenues and Gross Profit

Note Q: Revenues and Gross Profit

The Building Materials business includes the aggregates, cement, ready mixed concrete and asphalt and paving product lines. All cement, ready mixed concrete and asphalt and paving product lines are reported within the West Group. The following tables, which are reconciled to consolidated amounts, provide total revenues and gross profit by line of business: Building Materials (further divided by product line) and Magnesia Specialties. Interproduct revenues represent sales from the aggregates product line to the ready mixed concrete and asphalt and paving product lines and sales from the cement product line to the ready mixed concrete product line.

years ended December 31 (add 000) Total revenues	2018			2017			2016
Building Materials Business:
Products and services:
Aggregates	$	2,355,673		$	2,134,927		$	2,058,687
Cement		387,830			371,233			364,139
Ready Mixed Concrete		963,770			936,037			902,678
Asphalt and Paving		268,679			292,571			257,873
Less: Interproduct revenues		(264,237	)		(264,012	)		(247,111	)
Products and services		3,711,715			3,470,756			3,336,266
Freight		244,827			224,848			225,425
Total Building Materials Business		3,956,542			3,695,604			3,561,691
Magnesia Specialties:
Products and services		268,636			252,722			242,384
Freight		19,087			17,268			14,674
Total Magnesia Specialties		287,723			269,990			257,058
Consolidated total revenues	$	4,244,265		$	3,965,594		$	3,818,749


Gross profit (loss)
Building Materials Business:
Products and services:
Aggregates	$	606,759		$	599,670		$	556,131
Cement		126,213			117,021			119,894
Ready Mixed Concrete		74,175			91,646			99,085
Asphalt and Paving		52,917			64,693			53,025
Products and services		860,064			873,030			828,135
Freight		259			2,602			2,501
Total Building Materials Business		860,323			875,632			830,636
Magnesia Specialties:
Products and services		102,905			94,050			93,987
Freight		(4,223	)		(4,652	)		(4,384	)
Total Magnesia Specialties		98,682			89,398			89,603
Corporate		7,572			6,910			(8,501	)
Consolidated gross profit	$	966,577		$	971,940		$	911,738

Domestic and foreign total revenues are as follows:

years ended December 31 (add 000)	2018		2017		2016
Domestic	$	4,166,339	$	3,901,323	$	3,761,651
Foreign		77,926		64,271		57,098
Consolidated total revenues	$	4,244,265	$	3,965,594	$	3,818,749

Supplemental Cash Flow Information

12 Months Ended

Dec. 31, 2018

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

Note R: Supplemental Cash Flow Information

The components of the change in other assets and liabilities, net, are as follows:

years ended December 31

(add 000)	2018			2017			2016
Other current and noncurrent assets	$	(34,252	)	$	(19,424	)	$	9,171
Accrued salaries, benefits and payroll taxes		12,186			136			16,942
Accrued insurance and other taxes		(1,416	)		4,866			(2,688	)
Accrued income taxes		(10,336	)		(11,044	)		(12,523	)
Accrued pension, postretirement and postemployment benefits		(133,153	)		1,980			(15,955	)
Other current and noncurrent liabilities		(12,972	)		38,105			(6,053	)
Change in other assets and liabilities, net	$	(179,943	)	$	14,619		$	(11,106	)

Noncash investing and financing activities are as follows:

years ended December 31

(add 000)	2018		2017		2016
Accrued liabilities for purchases of property, plant and equipment	$	66,985	$	61,644	$	38,566
Acquisition of assets through capital lease	$	1,148	$	811	$	1,399
Acquisition of assets through asset exchange	$	-	$	2,476	$	-
Sale of asset to settle liability	$	-	$	900	$	-

Supplemental disclosures of cash flow information are as follows:

years ended December 31

(add 000)	2018		2017		2016
Cash paid for interest	$	137,239	$	78,902	$	73,664
Cash paid for income taxes	$	28,860	$	155,771	$	124,342

Other Operating (Income) and Expenses, Net

12 Months Ended

Dec. 31, 2018

Other Income And Expenses [Abstract]

Other Operating (Income) and Expenses, Net

Note S: Other Operating (Income) and Expenses, Net

Other operating income and expenses, net, are comprised generally of gains and losses on the sale of assets; asset and portfolio rationalization charges; gains and losses related to certain customer accounts receivable; rental, royalty and services income; accretion expense, depreciation expense and gains and losses related to asset retirement obligations. These net amounts represented income of $18,193,000 in 2018, an expense of $793,000 in 2017 and income of $8,043,000 in 2016. The 2018 amount reflects $18,838,000 of asset and portfolio rationalization charges, offset by $7,677,000 in net gains on legal settlements and $25,271,000 in gains on the sale of assets, primarily excess land. The 2017 amount reflects $19,366,000 of gains on the sale of assets, primarily excess land, offset by $12,668,000 of nonrecurring repair costs related to certain of the Company’s leased railcars and $10,813,000 of executive retirement expense.

The asset and portfolio rationalization charge relates to the Company’s Southwest ready mixed concrete operations reported in the West Group reportable segment. This charge reflects the Company’s evaluation of the recoverability of certain long-lived assets, including property, plant and equipment and intangible assets, for underperforming operations in this business and a reduction in workforce. Of the total charge, $16,970,000 is noncash and $1,868,000 will be settled in cash.

SCHEDULE II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2018

Valuation And Qualifying Accounts [Abstract]

SCHEDULE II - Valuation and Qualifying Accounts

SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS

MARTIN MARIETTA MATERIALS, INC. AND CONSOLIDATED SUBSIDIARIES

Col A	Col B		Col C					Col D			Col E
			Additions
Description	Balance at beginning of period		(1) Charged to costs and expenses		(2) Charged to other accounts- describe			Deductions-describe			Balance at end of period
	(Amounts in Thousands)

Year ended December 31, 2018
Allowance for doubtful accounts	$	2,390	$	963	$	-		$	-		$	3,353
Allowance for uncollectible notes receivable	227			-		-		227		^(a)		-
Inventory valuation allowance		143,961		36,878		5,158	^(b)		26,827	^(c)		159,170

Year ended December 31, 2017
Allowance for doubtful accounts	$	6,266	$	-	$	-		$	3,876	^(a)	$	2,390
Allowance for uncollectible notes receivable		437		-		-			210	^(a)	227
Inventory valuation allowance		134,862		38,488		-			29,389	^(c)		143,961

Year ended December 31, 2016
Allowance for doubtful accounts	$	6,940	$	-	$	-		$	674	^(a)	$	6,266
Allowance for uncollectible notes receivable		585		-		-			148	^(a)		437
Inventory valuation allowance		130,584		33,782		118	^(b)		29,622	^(c)		134,862

(a) Write off of uncollectible accounts and change in estimates.

(b) Application of reserve policy to acquired inventories.

Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Organization

Use of Estimates

Basis of Consolidation

Revenue Recognition

Freight and Delivery Costs

Cash and Cash Equivalents

Accounts Receivable

Inventories Valuation

Post-production stripping costs, which represent costs of removing overburden and waste materials to access mineral deposits, are a component of inventory production costs and recognized as incurred.

Property, Plant and Equipment

Property, Plant and Equipment. Property, plant and equipment are stated at cost.

The estimated service lives for property, plant and equipment are as follows:

Class of Assets		Range of Service Lives
Buildings		5 to 20 years
Machinery & Equipment		2 to 20 years
Land Improvements		5 to 60 years

Mineral reserves and mineral interests acquired in connection with a business combination are valued using an income approach over the life of the reserves.

Repair and Maintenance Costs

Repair and Maintenance Costs. Repair and maintenance costs that do not substantially extend the life of the Company’s plant and equipment are expensed as incurred.

Goodwill and Intangible Assets

Retirement Plans and Postretirement Benefits

Stock-Based Compensation

Environmental Matters

Income Taxes

Uncertain Tax Positions

Sales Taxes

Sales Taxes. Sales taxes collected from customers are recorded as liabilities until remitted to taxing authorities and therefore are not reflected in the consolidated statements of earnings.

Start-Up Costs

Start-Up Costs. Noncapital start-up costs for new facilities and products are charged to operations as incurred.

Warranties

Consolidated Comprehensive Earnings and Accumulated Other Comprehensive Loss

The components of the changes in accumulated other comprehensive loss and related cumulative noncurrent deferred tax assets are as follows:

	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Total
years ended December 31 (add 000)	2018
Accumulated other comprehensive loss at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		(22,890	)		(2,052	)		—			(24,942	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		10,187			—			280			10,467
Other comprehensive (loss) earnings, net of tax		(12,703	)		(2,052	)		280			(14,475	)
Accumulated other comprehensive loss at end of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)

Cumulative noncurrent deferred tax assets at end of period	$	84,207		$	—		$	—		$	84,207

	2017
Accumulated other comprehensive loss at beginning of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)
Other comprehensive (loss) earnings before reclassifications, net of tax		(8,062	)		1,140			—			(6,922	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		7,633			—			872			8,505
Other comprehensive (loss) earnings, net of tax		(429	)		1,140			872			1,583
Accumulated other comprehensive loss at end of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)

Cumulative noncurrent deferred tax assets at end of period	$	79,938		$	—		$	178		$	80,116

	2016
Accumulated other comprehensive loss at beginning of period	$	(103,380	)	$	(264	)	$	(1,978	)	$	(105,622	)
Other comprehensive loss before reclassifications, net of tax		(31,678	)		(898	)		—			(32,576	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		6,685			—			826			7,511
Other comprehensive (loss) earnings, net of tax		(24,993	)		(898	)		826			(25,065	)
Accumulated other comprehensive loss at end of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)

Cumulative noncurrent deferred tax assets at end of period	$	82,044		$	—		$	749		$	82,793

Reclassifications out of accumulated other comprehensive loss are as follows:

years ended December 31 (add 000)	2018			2017			2016			Affected line items in the consolidated statements of earnings
Pension and postretirement benefit plans
Special plan termination benefits	$	-		$	-		$	764
Settlement charge		2,936			21			115
Amortization of:
Prior service credit		(1,971	)		(1,430	)		(1,609	)
Actuarial loss		12,619			13,774			11,575
		13,584			12,365			10,845		Other nonoperating income, net
Tax effect		(3,397	)		(4,732	)		(4,160	)	Income tax expense (benefit)
Total	$	10,187		$	7,633		$	6,685
Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	458		$	1,443		$	1,367		Interest expense
Tax effect		(178	)		(571	)		(541	)	Income tax expense (benefit)
Total	$	280		$	872		$	826

Earnings Per Common Share

The following table reconciles the numerator and denominator for basic and diluted earnings per common share:

years ended December 31

(add 000)	2018		2017		2016
Net earnings attributable to Martin Marietta	$	469,998	$	713,342	$	425,386
Less: Distributed and undistributed earnings attributable to unvested participating securities		806		2,029		1,775
Basic and diluted net earnings attributable to common shareholders attributable to Martin Marietta	$	469,192	$	711,313	$	423,611

Basic weighted-average common shares outstanding		62,895		62,932		63,610
Effect of dilutive employee and director awards		252		285		251
Diluted weighted-average common shares outstanding		63,147		63,217		63,861

New Accounting Pronouncements

New Accounting Pronouncements.

Revenue from Contracts with Customers

Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments

Pending Accounting Pronouncements

Lease Standard

Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Estimated Service Lives for Property Plant and Equipment

The estimated service lives for property, plant and equipment are as follows:

Class of Assets		Range of Service Lives
Buildings		5 to 20 years
Machinery & Equipment		2 to 20 years
Land Improvements		5 to 60 years

Components of Changes in Accumulated Other Comprehensive Loss and Related Cumulative Noncurrent Deferred Tax Assets

The components of the changes in accumulated other comprehensive loss and related cumulative noncurrent deferred tax assets are as follows:

	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Total
years ended December 31 (add 000)	2018
Accumulated other comprehensive loss at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		(22,890	)		(2,052	)		—			(24,942	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		10,187			—			280			10,467
Other comprehensive (loss) earnings, net of tax		(12,703	)		(2,052	)		280			(14,475	)
Accumulated other comprehensive loss at end of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)

Cumulative noncurrent deferred tax assets at end of period	$	84,207		$	—		$	—		$	84,207

	2017
Accumulated other comprehensive loss at beginning of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)
Other comprehensive (loss) earnings before reclassifications, net of tax		(8,062	)		1,140			—			(6,922	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		7,633			—			872			8,505
Other comprehensive (loss) earnings, net of tax		(429	)		1,140			872			1,583
Accumulated other comprehensive loss at end of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)

Cumulative noncurrent deferred tax assets at end of period	$	79,938		$	—		$	178		$	80,116

	2016
Accumulated other comprehensive loss at beginning of period	$	(103,380	)	$	(264	)	$	(1,978	)	$	(105,622	)
Other comprehensive loss before reclassifications, net of tax		(31,678	)		(898	)		—			(32,576	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		6,685			—			826			7,511
Other comprehensive (loss) earnings, net of tax		(24,993	)		(898	)		826			(25,065	)
Accumulated other comprehensive loss at end of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)

Cumulative noncurrent deferred tax assets at end of period	$	82,044		$	—		$	749		$	82,793

Reclassification Out of Accumulated Other Comprehensive Loss

Reclassifications out of accumulated other comprehensive loss are as follows:

years ended December 31 (add 000)	2018			2017			2016			Affected line items in the consolidated statements of earnings
Pension and postretirement benefit plans
Special plan termination benefits	$	-		$	-		$	764
Settlement charge		2,936			21			115
Amortization of:
Prior service credit		(1,971	)		(1,430	)		(1,609	)
Actuarial loss		12,619			13,774			11,575
		13,584			12,365			10,845		Other nonoperating income, net
Tax effect		(3,397	)		(4,732	)		(4,160	)	Income tax expense (benefit)
Total	$	10,187		$	7,633		$	6,685
Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	458		$	1,443		$	1,367		Interest expense
Tax effect		(178	)		(571	)		(541	)	Income tax expense (benefit)
Total	$	280		$	872		$	826

Basic and Diluted Earnings Per Common Share

The following table reconciles the numerator and denominator for basic and diluted earnings per common share:

years ended December 31

(add 000)	2018		2017		2016
Net earnings attributable to Martin Marietta	$	469,998	$	713,342	$	425,386
Less: Distributed and undistributed earnings attributable to unvested participating securities		806		2,029		1,775
Basic and diluted net earnings attributable to common shareholders attributable to Martin Marietta	$	469,192	$	711,313	$	423,611

Basic weighted-average common shares outstanding		62,895		62,932		63,610
Effect of dilutive employee and director awards		252		285		251
Diluted weighted-average common shares outstanding		63,147		63,217		63,861

Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2018

Revenue From Contract With Customer [Abstract]

Schedule of Company's Total Revenues by Category for each Reportable Segment

The following table presents the Company’s total revenues by category for each reportable segment:

years ended December 31	Products and Services		Freight		Total
(add 000)	2018
Mid-America Group	$	1,133,754	$	89,482	$	1,223,236
Southeast Group		409,543		13,839		423,382
West Group		2,168,418		141,506		2,309,924
Total Building Materials Business		3,711,715		244,827		3,956,542
Magnesia Specialties		268,636		19,087		287,723
Total	$	3,980,351	$	263,914	$	4,244,265

	2017
Mid-America Group	$	982,214	$	71,112	$	1,053,326
Southeast Group		348,675		13,880		362,555
West Group		2,139,867		139,856		2,279,723
Total Building Materials Business		3,470,756		224,848		3,695,604
Magnesia Specialties		252,722		17,268		269,990
Total	$	3,723,478	$	242,116	$	3,965,594

	2016
Mid-America Group	$	945,193	$	71,905	$	1,017,098
Southeast Group		304,722		16,356		321,078
West Group		2,086,351		137,164		2,223,515
Total Building Materials Business		3,336,266		225,425		3,561,691
Magnesia Specialties		242,384		14,674		257,058
Total	$	3,578,650	$	240,099	$	3,818,749

Summary of Information About the Company's Contract Balances

The following table presents information about the Company’s contract balances:

December 31
(add 000)	2018		2017
Costs in excess of billings	$	1,975	$	1,310
Billings in excess of costs	$	6,743	$	7,204

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Changes in Goodwill

The following table shows the changes in goodwill by reportable segment and in total:

December 31	Mid- America Group		Southeast Group			West Group			Total
(add 000)	2018
Balance at beginning of period	$	281,403	$	50,346		$	1,828,541		$	2,160,290
Acquisitions		150,552		94,774			—			245,326
Goodwill allocated to assets held for sale		—		—			(5,571	)		(5,571	)
Divestitures		—		(927	)		—			(927	)
Balance at end of period	$	431,955	$	144,193		$	1,822,970		$	2,399,118

	2017
Balance at beginning of period	$	281,403	$	50,346		$	1,827,588		$	2,159,337
Acquisitions		—		—			230			230
Purchase price adjustments		—		—			723			723
Balance at end of period	$	281,403	$	50,346		$	1,828,541		$	2,160,290

Intangible Assets Subject to Amortization

Intangible assets subject to amortization consist of the following:

December 31	Gross Amount		Accumulated Amortization			Net Balance
(add 000)	2018
Noncompetition agreements	$	6,314	$	(6,179	)	$	135
Customer relationships		65,550		(25,575	)		39,975
Operating permits		458,951		(36,111	)		422,840
Use rights and other		16,745		(11,243	)		5,502
Trade names		12,800		(9,697	)		3,103
Total	$	560,360	$	(88,805	)	$	471,555

	2017
Noncompetition agreements	$	6,274	$	(6,144	)	$	130
Customer relationships		45,955		(17,551	)		28,404
Operating permits		458,951		(26,435	)		432,516
Use rights and other		16,745		(10,176	)		6,569
Trade names		12,800		(7,947	)		4,853
Total	$	540,725	$	(68,253	)	$	472,472

Intangible Assets Deemed to Indefinite Life and Not Being Amortized

Intangible assets deemed to have an indefinite life and not being amortized consist of the following:

December 31	Building Materials Business		Magnesia Specialties		Total
(add 000)	2018
Operating permits	$	6,600	$	—	$	6,600
Use rights		20,282		—		20,282
Trade names		280		2,565		2,845
Total	$	27,162	$	2,565	$	29,727
	2017
Operating permits	$	6,600	$	—	$	6,600
Use rights		24,432		—		24,432
Trade names		280		2,565		2,845
Total	$	31,312	$	2,565	$	33,877

Schedule of Acquired Intangibles

During 2018, the Company acquired $21,760,000 of intangible assets, consisting of the following:

(add 000, except year data)	Amount		Weighted-average amortization period
Subject to amortization:
Customer relationships	$	20,620	12 years
Noncompetition agreements		40	10 years
Total subject to amortization		20,660	12 years

Not subject to amortization:
Use rights		1,100	N/A
Total	$	21,760

Estimated Amortization Expense of Intangible Assets

The estimated amortization expense for intangible assets for each of the next five years and thereafter is as follows:

(add 000)
2019	$	13,203
2020		13,168
2021		12,462
2022		11,036
2023		10,592
Thereafter		411,094
Total	$	471,555

Business Combinations (Tables)

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Summary of the Preliminary Estimated Fair Values of the Assets Acquired and the Liabilities Assumed

The following is a summary of the preliminary estimated fair values of the assets acquired and the liabilities assumed:

(add 000)
Assets:
Cash and cash equivalents	$	1,159
Receivables		25,479
Inventory		46,635
Other current assets		1,029
Property, plant and equipment		1,519,289
Intangible assets, other than goodwill		20,150
Goodwill		244,615
Total Assets		1,858,356
Liabilities:
Accounts payable and accrued expenses		17,978
Deferred income tax liabilities, net		214,020
Noncontrolling interest		9,001
Total Liabilities		240,999
Total Consideration	$	1,617,357

Business Acquisition, Pro Forma Information

year ended December 31
(add 000)	2018		2017
Total revenues	$	4,299,673	$	4,178,627
Net earnings attributable to Martin Marietta	$	489,526	$	691,719
Diluted earnings per share	$	7.75	$	10.94

Accounts Receivable, Net (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Schedule of Accounts Receivable Net

December 31
(add 000)	2018			2017
Customer receivables	$	514,094		$	480,073
Other current receivables		12,535			9,557
		526,629			489,630
Less: Allowances		(3,353	)		(2,390	)
Total	$	523,276		$	487,240

Inventories, Net (Tables)

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Schedule of Inventories Net

December 31

(add 000)	2018			2017
Finished products	$	615,719		$	552,999
Products in process and raw materials		66,920			62,761
Supplies and expendable parts		139,566			128,792
		822,205			744,552
Less: Allowances		(159,170	)		(143,961	)
Total	$	663,035		$	600,591

Property, Plant and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property, Plant and Equipment, Net

December 31

(add 000)	2018			2017
Land and land improvements	$	1,089,675		$	974,622
Mineral reserves and interests		2,506,817			1,162,289
Buildings		162,098			154,564
Machinery and equipment		4,357,705			4,006,619
Construction in progress		178,668			199,973
		8,294,963			6,498,067
Less: Accumulated depreciation, depletion and amortization		(3,137,734	)		(2,905,254	)
Total	$	5,157,229		$	3,592,813

Gross Asset Value and Accumulated Amortization for Machinery and Equipment Recorded under Capital Lease

Included in these amounts are the gross asset value and accumulated amortization for machinery and equipment recorded under capital leases at December 31 as follows:

(add 000)	2018			2017
Machinery and equipment under capital leases	$	24,931		$	23,919
Less: Accumulated amortization		(14,524	)		(11,243	)
Total	$	10,407		$	12,676

Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Long-Term Debt

December 31 (add 000)	2018			2017
4.25% Senior Notes, due 2024	$	396,398		$	395,814
7% Debentures, due 2025		124,272			124,180
3.450% Senior Notes, due 2027		296,939			296,628
3.500% Senior Notes, due 2027		494,765			494,352
6.25% Senior Notes, due 2037		228,094			228,033
4.250% Senior Notes, due 2047		591,541			591,688
Floating Rate Senior Notes, due 2019, interest rate of 3.29% and 2.13% at December 31, 2018 and 2017, respectively		299,260			298,102
Floating Rate Senior Notes, due 2020, interest rate of 3.30% and 2.10% at December 31, 2018 and 2017, respectively		298,956			298,227
6.60% Senior Notes, due 2018		-			299,871
Trade Receivable Facility, interest rate of 3.07% at December 31, 2018		390,000			-
Other notes		256			308
Total		3,120,481			3,027,203
Less: current maturities		(390,042	)		(299,909	)
Long-term debt	$	2,730,439		$	2,727,294

Schedule of Principal Amount, Effective Interest Rate and Maturity Date for Corporation's Senior Notes

	Principal Amount (add 000)		Effective Interest Rate	Maturity Date
4.25% Senior Notes	$	400,000	4.25%	July 2, 2024
7% Debentures	$	125,000	7.12%	December 1, 2025
3.450% Senior Notes	$	300,000	3.47%	June 1, 2027
3.500% Senior Notes	$	500,000	3.53%	December 15, 2027
6.25% Senior Notes	$	230,000	6.45%	May 1, 2037
4.250% Senior Notes	$	600,000	4.27%	December 15, 2047
Floating Rate Senior Notes, due 2019	$	300,000	Three-month LIBOR + 0.50%	December 20, 2019
Floating Rate Senior Notes, due 2020	$	300,000	Three-month LIBOR + 0.65%	May 22, 2020

Schedule of Corporation's Long-Term Debt Maturities

The Company’s long-term debt maturities for the five years following December 31, 2018, and thereafter are:

(add 000)
2019	$	390,042
2020		299,015
2021		65
2022		90
2023		299,260
Thereafter		2,132,009
Total	$	3,120,481

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Components of Income Tax Expense (Benefit)

The components of the Company’s income tax expense (benefit) are as follows:

years ended December 31 (add 000)	2018			2017			2016
Federal income taxes:
Current	$	15,285		$	129,236		$	97,975
Deferred		69,599			(239,304	)		68,899
Total federal income taxes		84,884			(110,068	)		166,874
State income taxes:
Current		5,986			14,843			15,189
Deferred		14,134			(882	)		(1,149	)
Total state income taxes		20,120			13,961			14,040
Foreign income taxes:
Current		(1,354	)		1,175			1,064
Deferred		2,055			475			(394	)
Total foreign income taxes		701			1,650			670
Income tax expense (benefit)	$	105,705		$	(94,457	)	$	181,584

Summary of Effective Income Tax Rate

The Company’s effective income tax rate varied from the statutory United States income tax rate because of the following tax differences:

years ended December 31	2018			2017			2016
Statutory income tax rate		21.0	%		35.0	%		35.0	%
(Reduction) increase resulting from:
Impact from 2017 Tax Act		(3.3	)		(41.7	)		—
Effect of statutory depletion		(3.4	)		(5.6	)		(5.4	)
State income taxes, net of federal tax benefit		2.8			1.5			1.5
Stock based compensation		(0.5	)		(1.0	)		(0.1	)
Domestic production deduction		—			(2.2	)		(2.0	)
Other items		1.7			(1.3	)		0.9
Effective income tax rate		18.3	%	(15.3%)				29.9	%

Components of Deferred Tax Assets and Liabilities

The principal components of the Company’s deferred tax assets and liabilities are as follows:

December 31	Deferred Assets (Liabilities)
(add 000)	2018			2017
Deferred tax assets related to:
Employee benefits	$	-		$	16,059
Inventories		52,618			56,242
Valuation and other reserves		22,359			22,989
Net operating loss carryforwards		10,990			11,780
Accumulated other comprehensive loss		84,207			80,116
Other items, net		3,052			3,963
Gross deferred tax assets		173,226			191,149
Valuation allowance on deferred tax assets		(8,604	)		(10,349	)
Total net deferred tax assets		164,622			180,800
Deferred tax liabilities related to:
Property, plant and equipment		(478,329	)		(407,400	)
Partnerships and joint ventures		(204,315	)		(15,617	)
Goodwill and other intangibles		(170,538	)		(168,506	)
Employee benefits		(17,004	)		-
Total deferred tax liabilities		(870,186	)		(591,523	)
Deferred income taxes, net	$	(705,564	)	$	(410,723	)

Schedule of Unrecognized Tax Benefits Excluding Interest Correlative Effects

The following table summarizes the Company’s unrecognized tax benefits, excluding interest and correlative effects:

years ended December 31 (add 000)	2018			2017			2016
Unrecognized tax benefits at beginning of year	$	22,367		$	21,807		$	18,727
Gross increases – tax positions in prior years		944			1,396			2,401
Gross decreases – tax positions in prior years		-			(672	)		(1,924	)
Gross increases – tax positions in current year		1,802			4,961			4,650
Gross decreases – tax positions in current year		(1,013	)		(946	)		(2,047	)
Lapse of statute of limitations		—			(4,179	)		—
Unrecognized tax benefits at end of year	$	24,100		$	22,367		$	21,807

Amount that, if recognized, would favorably impact the effective tax rate	$	12,820		$	10,399		$	11,603

Retirement Plans, Postretirement and Postemployment Benefits (Tables)

12 Months Ended

Dec. 31, 2018

Fair Values of Pension Plan Assets by Asset Class and Fair Value Hierarchy Level

The fair values of pension plan assets by asset class and fair value hierarchy level are as follows:

	Fair Value Measurements
December 31	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Net Asset Value		Total Fair Value
(add 000)	2018
Equity securities¹:
Mid-sized to large cap	$	—	$	—	$	—	$	196,475	$	196,475
Small cap, international and emerging growth funds		—		—		—		210,371		210,371
Debt securities¹:
Core fixed income		—		—		—		228,194		228,194
Real estate		—		—		—		35,553		35,553
Hedge funds		—		—		—		44,453		44,453
Cash equivalents		2,864		—		—		—		2,864
Total	$	2,864	$	—	$	—	$	715,046	$	717,910

	2017
Equity securities¹:
Mid-sized to large cap	$	—	$	—	$	—	$	177,497	$	177,497
Small cap, international and emerging growth funds		—		—		—		186,272		186,272
Debt securities¹:
Core fixed income		—		—		—		182,225		182,225
Real estate		—		—		—		46,467		46,467
Hedge funds		—		—		—		45,604		45,604
Cash equivalents		41		—		—		—		41
Total	$	41	$	—	$	—	$	638,065	$	638,106

¹ These investments are common collective investment trusts valued using the net asset value (NAV) unit price provided by the fund administrator. The NAV is based on the value of the underlying assets owned by the fund.

Schedule of Assumed Health Care Cost Trend Rates

Assumed health care cost trend rates at December 31 are:

	2018	2017
Health care cost trend rate assumed for next year	7.0%	7.0%
Rate to which the cost trend rate gradually declines	5.0%	5.0%
Year the rate reaches the ultimate rate	2023	2022

Schedule of One Percentage-Point Change in Assumed Health Care Cost Trend Rates

A one percentage-point change in assumed health care cost trend rates would have the following effects:

	One Percentage Point
(add 000)	Increase		(Decrease)
Total service and interest cost components	$	25	$	(22	)
Postretirement benefit obligation	$	640	$	(575	)

Pension

Schedule of Components of Net Periodic Benefit Cost (Credit)

The net periodic retirement benefit cost of defined benefit plans includes the following components:

years ended December 31 (add 000)	2018			2017			2016
Service cost	$	31,624		$	26,805		$	22,167
Interest cost		33,209			36,101			35,879
Expected return on assets		(46,011	)		(39,759	)		(37,699	)
Amortization of:
Prior service cost		104			311			350
Actuarial loss		12,830			14,138			12,074
Transition asset		(1	)		(1	)		(1	)
Settlement charge		2,936			21			124
Termination benefit charge		—			—			764
Net periodic benefit cost	$	34,691		$	37,616		$	33,658

Schedule of Recognized Comprehensive Earnings

The Company recognized the following amounts in consolidated comprehensive earnings:

years ended December 31

(add 000)	2018			2017			2016
Actuarial loss	$	32,214		$	13,343		$	52,028
Net prior service cost		3			—			—
Amortization of:
Prior service cost		(104	)		(311	)		(350	)
Actuarial loss		(12,830	)		(14,138	)		(12,074	)
Transition asset		1			1			1
Special plan termination benefits		—			—			(764	)
Settlement charge		(2,936	)		(21	)		(124	)
Total	$	16,348		$	(1,126	)	$	38,717

Schedule of Net Periodic Benefit Credit or Cost Not Yet Recognized

Accumulated other comprehensive loss includes the following amounts that have not yet been recognized in net periodic benefit cost:

December 31	2018						2017
(add 000)	Gross			Net of tax			Gross			Net of tax
Prior service cost	$	14		$	9		$	115		$	71
Actuarial loss		233,688			146,588			217,240			134,066
Transition asset		(5	)		(3	)		(6	)		(4	)
Total	$	233,697		$	146,594		$	217,349		$	134,133

Schedule of Change in Projected Benefit Obligation

The defined benefit plans’ change in projected benefit obligation is as follows:

years ended December 31

(add 000)	2018			2017
Net projected benefit obligation at beginning of year	$	879,335		$	831,849
Service cost		31,624			26,805
Interest cost		33,209			36,101
Actuarial (gain) loss		(54,621	)		56,675
Plan amendment		3			-
Gross benefits paid		(41,654	)		(72,095	)
Net projected benefit obligation at end of year	$	847,896		$	879,335

Schedule of Change In Plan Assets

The Company’s change in plan assets, funded status and amounts recognized on the Company’s consolidated balance sheets are as follows:

years ended December 31

(add 000)	2018			2017
Change in plan assets:
Fair value of plan assets at beginning of year	$	638,106		$	596,207
Actual return on plan assets, net		(40,823	)		83,091
Employer contributions		162,281			30,903
Gross benefits paid		(41,654	)		(72,095	)
Fair value of plan assets at end of year	$	717,910		$	638,106

Schedule of Funded Status

December 31

(add 000)	2018			2017
Funded status of the plan at end of year	$	(129,986	)	$	(241,229	)
Accrued benefit cost	$	(129,986	)	$	(241,229	)

Schedule of Amounts Recognized on Consolidated Balance Sheets

December 31

(add 000)	2018			2017
Amounts recognized on consolidated balance sheets consist of:
Current liability	$	(8,992	)	$	(11,092	)
Noncurrent liability		(120,994	)		(230,137	)
Net amount recognized at end of year	$	(129,986	)	$	(241,229	)

Schedule of Accumulated Benefit Obligations in Excess of Plan Assets

Benefit obligations and fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets are as follows:

December 31

(add 000)	2018		2017
Projected benefit obligation	$	98,729	$	879,335
Accumulated benefit obligation	$	85,548	$	792,912
Fair value of plan assets	$	560	$	638,106

Schedule of Weighted-Average Assumptions

Weighted-average assumptions used to determine benefit obligations as of December 31 are:

	2018	2017
Discount rate	4.38%	3.76%
Rate of increase in future compensation levels	4.50%	4.50%

Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31 are:

	2018	2017	2016
Discount rate	3.76%	4.29%	4.67%
Rate of increase in future compensation levels	4.50%	4.50%	4.50%
Expected long-term rate of return on assets	6.75%	6.75%	7.00%

Schedule of Target Assets Allocation

The target allocation for 2018 and the actual pension plan asset allocation by asset class are as follows:

	Percentage of Plan Assets
	2018	December 31
Asset Class	Target Allocation	2018	2017
Equity securities	56%	57%	57%
Debt securities	30%	32%	29%
Hedge funds	4%	6%	7%
Real estate	10%	5%	7%
Total	100%	100%	100%

Schedule of Expected Benefit Payments

The expected benefit payments to be paid from plan assets for each of the next five years and the five-year period thereafter are as follows:

(add 000)
2019	$	40,835
2020	$	42,908
2021	$	44,237
2022	$	45,848
2023	$	47,170
Years 2024 - 2028	$	260,117

Postretirement Benefits

Schedule of Components of Net Periodic Benefit Cost (Credit)

The net periodic postretirement benefit credit for postretirement plans includes the following components:

years ended December 31

(add 000)	2018			2017			2016
Service cost	$	77		$	80		$	85
Interest cost		519			727			863
Amortization of:
Prior service credit		(2,074	)		(1,741	)		(1,959	)
Actuarial gain		(211	)		(364	)		(499	)
Settlement credit		—			—			(9	)
Total net periodic benefit credit	$	(1,689	)	$	(1,298	)	$	(1,519	)

Schedule of Recognized Comprehensive Earnings

The Company recognized the following amounts in consolidated comprehensive earnings:

years ended December 31

(add 000)	2018			2017			2016
Actuarial (gain) loss	$	(1,700	)	$	1,236		$	686
Net prior service credit		—			(3,902	)		(1,326	)
Settlement credit		—			—			9
Amortization of:
Prior service credit		2,074			1,741			1,959
Actuarial gain		211			364			499
Total	$	585		$	(561	)	$	1,827

Schedule of Net Periodic Benefit Credit or Cost Not Yet Recognized

Accumulated other comprehensive loss includes the following amounts that have not yet been recognized in net periodic benefit credit or cost:

December 31	2018						2017
(add 000)	Gross			Net of tax			Gross			Net of tax
Prior service credit	$	(3,747	)	$	(2,388	)	$	(6,314	)	$	(3,899	)
Actuarial gain		(4,238	)		(2,701	)		(2,256	)		(1,393	)
Total	$	(7,985	)	$	(5,089	)	$	(8,570	)	$	(5,292	)

Schedule of Change in Projected Benefit Obligation

The postretirement health care plans’ change in benefit obligation is as follows:

years ended December 31

(add 000)	2018			2017
Change in benefit obligation:
Net benefit obligation at beginning of year	$	15,347		$	20,591
Service cost		77			80
Interest cost		519			727
Participants’ contributions		312			3,421
Actuarial (gain) loss		(1,700	)		1,236
Gross benefits paid		(1,262	)		(6,806	)
Plan amendments		-			(3,902	)
Net benefit obligation at end of year	$	13,293		$	15,347

Schedule of Change In Plan Assets

The postretirement health care plans’ change in plan assets, funded status and amounts recognized on the Company’s consolidated balance sheets are as follows:

years ended December 31

(add 000)	2018			2017
Fair value of plan assets at beginning of year:	$	—		$	—
Employer contributions		950			3,385
Participants’ contributions		312			3,421
Gross benefits paid		(1,262	)		(6,806	)
Fair value of plan assets at end of year	$	—		$	—

Schedule of Funded Status

December 31

(add 000)	2018			2017
Funded status of the plan at end of year	$	(13,293	)	$	(15,347	)
Accrued benefit cost	$	(13,293	)	$	(15,347	)

Schedule of Amounts Recognized on Consolidated Balance Sheets

December 31

(add 000)	2018			2017
Amounts recognized on consolidated balance sheets consist of:
Current liability	$	(950	)	$	(2,560	)
Noncurrent liability		(12,343	)		(12,787	)
Net amount recognized at end of year	$	(13,293	)	$	(15,347	)

Schedule of Weighted-Average Assumptions

Weighted-average assumptions used to determine the postretirement benefit obligation as of December 31 are:

		2018				2017
Discount rate			4.15	%			3.47	%

Weighted-average assumptions used to determine net postretirement benefit credit for the years ended December 31 are:

		2018				2017							2016
Discount rate			3.47	%				3.78		%					4.25		%

Schedule of Expected Benefit Payments

The total expected benefit payments to be paid by the Company, net of participant contributions, for each of the next five years and the five-year period thereafter are as follows:

(add 000)
2019	$	950
2020	$	1,492
2021	$	1,419
2022	$	1,344
2023	$	1,254
Years 2024 – 2028	$	5,809

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary Information for Restricted Stock Awards and Incentive Compensation Stock Awards

The following table summarizes information for restricted stock awards and incentive compensation stock awards for 2018:

	Restricted Stock - Service Based					Restricted Stock - Performance Based					Incentive Compensation Stock
	Number of Awards			Weighted- Average Grant-Date Fair Value		Number of Awards			Weighted- Average Grant-Date Fair Value		Number of Awards			Weighted- Average Grant-Date Fair Value
January 1, 2018		314,840		$	151.84		139,999		$	150.34		38,510		$	166.67
Awarded		64,352		$	211.03		37,138		$	212.12		18,180		$	212.12
Distributed		(88,674	)	$	159.04		(20,219	)	$	126.01		(20,992	)	$	138.54
Forfeited		(12,371	)	$	211.63		(4,979	)	$	182.90		(322	)	$	184.74
December 31, 2018		278,147		$	158.29		151,939		$	174.74		35,376		$	206.55

Summary Information for Stock Options

The following table includes summary information for stock options as of December 31, 2018:

	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Life (years)
Outstanding at January 1, 2018		301,958		$	91.44
Exercised		(89,557	)	$	81.06
Terminated		(2,011	)	$	83.32
Outstanding at December 31, 2018		210,390		$	95.93		3.6

Exercisable at December 31, 2018		197,241		$	92.02		3.4

Schedule of Stock-Based Compensation Expense

(add 000, except year data)	Stock Options		Restricted Stock		Incentive Compensation Stock		Directors’ Awards		Total
Stock-based compensation expense recognized for years ended December 31:
2018	$	242	$	27,650	$	729	$	632	$	29,253
2017	$	684	$	28,657	$	661	$	458	$	30,460
2016	$	1,646	$	17,747	$	442	$	646	$	20,481
Unrecognized compensation cost at December 31, 2018:	$	50	$	21,992	$	495	$	—	$	22,537
Weighted-average period over which unrecognized compensation cost will be recognized:	0.4 years		1.6 years		1.6 years

Stock-Based Compensation Expense in Future for Outstanding Awards

The following presents expected stock-based compensation expense in future periods for outstanding awards as of December 31, 2018:

(add 000)
2019	$	16,191
2020		5,843
2021		409
2022		94
Total	$	22,537

Leases (Tables)

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Future Minimum Lease and Royalty Commitments for All Noncancelable Agreements

Future minimum lease and royalty commitments for all noncancelable agreements and capital lease obligations as of December 31, 2018 are as follows:

(add 000)	Capital Leases			Operating Leases		Royalty Commitments
2019	$	3,718		$	105,955	$	14,614
2020		2,695			70,478		11,364
2021		1,735			60,382		10,335
2022		1,004			57,531		9,545
2023		713			56,511		8,109
Thereafter		3,893			318,147		65,981
Total		13,758		$	669,004	$	119,948
Less: imputed interest		(2,879	)
Present value of minimum lease payments		10,879
Less: current capital lease obligations		(3,249	)
Long-term capital lease obligations	$	7,630

Future Minimum Lease Commitments for Capital Lease Obligations

Future minimum lease and royalty commitments for all noncancelable agreements and capital lease obligations as of December 31, 2018 are as follows:

(add 000)	Capital Leases			Operating Leases		Royalty Commitments
2019	$	3,718		$	105,955	$	14,614
2020		2,695			70,478		11,364
2021		1,735			60,382		10,335
2022		1,004			57,531		9,545
2023		713			56,511		8,109
Thereafter		3,893			318,147		65,981
Total		13,758		$	669,004	$	119,948
Less: imputed interest		(2,879	)
Present value of minimum lease payments		10,879
Less: current capital lease obligations		(3,249	)
Long-term capital lease obligations	$	7,630

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Changes in Asset Retirement Obligations

The following shows the changes in the asset retirement obligations:

years ended December 31:

(add 000)	2018			2017
Balance at beginning of year	$	109,653		$	101,106
Accretion expense		5,074			4,768
Liabilities incurred and liabilities assumed in business combinations		4,692			7,940
Liabilities settled		(2,821	)		(309	)
Revisions in estimated cash flows		5,206			(3,852	)
Balance at end of year	$	121,804		$	109,653

Schedule of Contractual Purchase Commitments

The Company’s contractual purchase commitments as of December 31, 2018 are as follows:

(add 000)

2019	$	181,768
2020		14,177
2021		6,264
2022		3,689
2023		1,931
Thereafter		17,195
Total	$	225,024

Segments (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Financial Data for Continuing Operation for Company's Reportable Segments

years ended December 31 (add 000) Total revenues	2018		2017		2016
Mid-America Group	$	1,223,236	$	1,053,326	$	1,017,098
Southeast Group		423,382		362,555		321,078
West Group		2,309,924		2,279,723		2,223,515
Total Building Materials Business		3,956,542		3,695,604		3,561,691
Magnesia Specialties		287,723		269,990		257,058
Total	$	4,244,265	$	3,965,594	$	3,818,749

Gross profit (loss)
Mid-America Group	$	366,918	$	335,394	$	306,560
Southeast Group		77,193		74,642		57,286
West Group		416,212		465,596		466,790
Total Building Materials Business		860,323		875,632		830,636
Magnesia Specialties		98,682		89,398		89,603
Corporate		7,572		6,910		(8,501	)
Total	$	966,577	$	971,940	$	911,738

Selling, general and administrative expenses
Mid-America Group	$	55,775	$	53,937	$	52,712
Southeast Group		18,727		17,144		17,245
West Group		107,613		102,650		95,631
Total Building Materials Business		182,115		173,731		165,588
Magnesia Specialties		9,999		9,537		9,617
Corporate		88,440		78,860		66,401
Total	$	280,554	$	262,128	$	241,606

Earnings (Loss) from operations
Mid-America Group	$	319,139		$	284,789		$	258,422
Southeast Group		75,840			61,238			41,653
West Group		295,801			360,544			379,417
Total Building Materials Business		690,780			706,571			679,492
Magnesia Specialties		88,063			79,431			79,306
Corporate		(88,106	)		(85,621	)		(81,532	)
Total	$	690,737		$	700,381		$	677,266

Earnings from operations for the West Group for 2018 reflect asset and portfolio rationalization impairment charges of $18,838,000.

(add 000) Depreciation, depletion and amortization	2018		2017		2016
Mid-America Group	$	93,639	$	69,691	$	64,295
Southeast Group		41,214		30,780		30,590
West Group		180,870		169,853		164,653
Total Building Materials Business		315,723		270,324		259,538
Magnesia Specialties		10,413		10,070		10,354
Corporate		17,897		16,768		15,361
Total	$	344,033	$	297,162	$	285,253

December 31 (add 000) Assets employed	2018		2017		2016
Mid-America Group	$	2,788,454	$	1,532,867	$	1,406,526
Southeast Group		1,299,469		616,344		594,967
West Group		4,989,639		5,014,231		4,904,018
Total Building Materials Business		9,077,562		7,163,442		6,905,511
Magnesia Specialties		156,106		152,257		150,969
Corporate		317,751		1,676,812		244,425
Total	$	9,551,419	$	8,992,511	$	7,300,905

Total property additions, including the impact of acquisitions
Mid-America Group	$	1,157,073	$	139,505	$	152,014
Southeast Group		603,078		34,636		30,588
West Group		148,164		240,793		338,795
Total Building Materials Business		1,908,315		414,934		521,397
Magnesia Specialties		12,450		11,129		8,944
Corporate		4,838		12,558		10,430
Total	$	1,925,603	$	438,621	$	540,771

Property additions through acquisitions
Mid-America Group	$	980,236	$	60	$	1,524
Southeast Group		561,503		—		—
West Group		1,421		2,420		132,112
Total Building Materials Business		1,543,160		2,480		133,636
Magnesia Specialties		—		—		—
Corporate		—		—		—
Total	$	1,543,160	$	2,480	$	133,636

Revenues and Gross Profit (Tables)

12 Months Ended

Dec. 31, 2018

Revenues And Gross Profit [Abstract]

Total Revenues and Gross Profit by Product Line

The following tables, which are reconciled to consolidated amounts, provide total revenues and gross profit by line of business: Building Materials (further divided by product line) and Magnesia Specialties. Interproduct revenues represent sales from the aggregates product line to the ready mixed concrete and asphalt and paving product lines and sales from the cement product line to the ready mixed concrete product line.

years ended December 31 (add 000) Total revenues	2018			2017			2016
Building Materials Business:
Products and services:
Aggregates	$	2,355,673		$	2,134,927		$	2,058,687
Cement		387,830			371,233			364,139
Ready Mixed Concrete		963,770			936,037			902,678
Asphalt and Paving		268,679			292,571			257,873
Less: Interproduct revenues		(264,237	)		(264,012	)		(247,111	)
Products and services		3,711,715			3,470,756			3,336,266
Freight		244,827			224,848			225,425
Total Building Materials Business		3,956,542			3,695,604			3,561,691
Magnesia Specialties:
Products and services		268,636			252,722			242,384
Freight		19,087			17,268			14,674
Total Magnesia Specialties		287,723			269,990			257,058
Consolidated total revenues	$	4,244,265		$	3,965,594		$	3,818,749


Gross profit (loss)
Building Materials Business:
Products and services:
Aggregates	$	606,759		$	599,670		$	556,131
Cement		126,213			117,021			119,894
Ready Mixed Concrete		74,175			91,646			99,085
Asphalt and Paving		52,917			64,693			53,025
Products and services		860,064			873,030			828,135
Freight		259			2,602			2,501
Total Building Materials Business		860,323			875,632			830,636
Magnesia Specialties:
Products and services		102,905			94,050			93,987
Freight		(4,223	)		(4,652	)		(4,384	)
Total Magnesia Specialties		98,682			89,398			89,603
Corporate		7,572			6,910			(8,501	)
Consolidated gross profit	$	966,577		$	971,940		$	911,738

Domestic and Foreign Total Revenues

Domestic and foreign total revenues are as follows:

years ended December 31 (add 000)	2018		2017		2016
Domestic	$	4,166,339	$	3,901,323	$	3,761,651
Foreign		77,926		64,271		57,098
Consolidated total revenues	$	4,244,265	$	3,965,594	$	3,818,749

Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2018

Supplemental Cash Flow Elements [Abstract]

Components of Change in Other Assets and Liabilities, Net

The components of the change in other assets and liabilities, net, are as follows:

years ended December 31

(add 000)	2018			2017			2016
Other current and noncurrent assets	$	(34,252	)	$	(19,424	)	$	9,171
Accrued salaries, benefits and payroll taxes		12,186			136			16,942
Accrued insurance and other taxes		(1,416	)		4,866			(2,688	)
Accrued income taxes		(10,336	)		(11,044	)		(12,523	)
Accrued pension, postretirement and postemployment benefits		(133,153	)		1,980			(15,955	)
Other current and noncurrent liabilities		(12,972	)		38,105			(6,053	)
Change in other assets and liabilities, net	$	(179,943	)	$	14,619		$	(11,106	)

Schedule Of Other Significant Noncash Transactions

Noncash investing and financing activities are as follows:

years ended December 31

(add 000)	2018		2017		2016
Accrued liabilities for purchases of property, plant and equipment	$	66,985	$	61,644	$	38,566
Acquisition of assets through capital lease	$	1,148	$	811	$	1,399
Acquisition of assets through asset exchange	$	-	$	2,476	$	-
Sale of asset to settle liability	$	-	$	900	$	-

Supplemental Disclosures of Cash Flow Information

Supplemental disclosures of cash flow information are as follows:

years ended December 31

(add 000)	2018		2017		2016
Cash paid for interest	$	137,239	$	78,902	$	73,664
Cash paid for income taxes	$	28,860	$	155,771	$	124,342

Accounting Policies - Additional Information (Detail)	12 Months Ended
Accounting Policies - Additional Information (Detail)	Dec. 31, 2018 USD ($) Facility State Plant shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares
Significant Accounting Policies [Line Items]
Number of states with aggregates business sales by destination \| State	31
Number of cement plants \| Plant	2
Number of cement distribution facilities \| Facility	4
Number of asphalt plants \| Plant	9
Retirement plans and postretirement benefits amortized amount representing percentage of greater of projected benefit obligation or pension plan assets.	10.00%
Minimum likelihood for recognition of tax benefit related to uncertain tax position	50.00%
ASU 2016-15 \| Reduction in Net Cash Provided by Operating Activities
Significant Accounting Policies [Line Items]
Increase/decrease due to adoption of ASU		$ 280,000	$ 293,000
ASU 2016-15 \| Reduction in Net Cash used for Investing Activities
Significant Accounting Policies [Line Items]
Increase/decrease due to adoption of ASU		$ 280,000	$ 293,000
Stock Options
Significant Accounting Policies [Line Items]
Stock options issued \| shares	0	0	0
Expendable Parts Inventory
Significant Accounting Policies [Line Items]
Allowance for inventories in excess of sales requisite Record period	5 years
Supplies Inventory
Significant Accounting Policies [Line Items]
Allowance for inventories in excess of sales requisite Record period	1 year
Minimum
Significant Accounting Policies [Line Items]
Number of quarries and yards \| Facility	300
Number of ready mixed concrete plants \| Plant	140
Warranty term	9 months
Minimum \| ASC 842 \| Increase in Liabilities
Significant Accounting Policies [Line Items]
Increase/decrease due to adoption of ASU	$ 475,000,000
Minimum \| ASC 842 \| Increase in Assets
Significant Accounting Policies [Line Items]
Increase/decrease due to adoption of ASU	$ 475,000,000
Minimum \| Inventory Finished Goods
Significant Accounting Policies [Line Items]
Allowance for inventories in excess of sales requisite Record period	12 months
Maximum
Significant Accounting Policies [Line Items]
Warranty term	1 year
Maximum \| ASC 842 \| Increase in Liabilities
Significant Accounting Policies [Line Items]
Increase/decrease due to adoption of ASU	$ 550,000,000
Maximum \| ASC 842 \| Increase in Assets
Significant Accounting Policies [Line Items]
Increase/decrease due to adoption of ASU	$ 550,000,000
Maximum \| Inventory Finished Goods
Significant Accounting Policies [Line Items]
Allowance for inventories in excess of sales requisite Record period	5 years
Percentage of Aggregates Business Net Sales in Top Five Sales states \| Geographic Concentration Risk \| Sales Revenue Segment
Significant Accounting Policies [Line Items]
Total net sales, percentage	72.00%

Accounting Policies - Estimated Service Lives for Property, Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2017
Building \| Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Service Lives, Years	5 years
Building \| Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Service Lives, Years	20 years
Machinery and Equipment \| Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Service Lives, Years	2 years
Machinery and Equipment \| Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Service Lives, Years	20 years
Land Improvements \| Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Service Lives, Years	5 years
Land Improvements \| Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Service Lives, Years	60 years

Accounting Policies - Components of Changes in Accumulated Other Comprehensive Loss and Related Cumulative Noncurrent Deferred Tax Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 4,682,477	$ 4,142,590	$ 4,060,177
Other comprehensive (loss) earnings before reclassifications, net of Tax	(24,942)	(6,922)	(32,576)
Amounts reclassified from accumulated other comprehensive loss, net of tax	10,467	8,505	7,511
Other comprehensive (loss) earnings, net of tax	(14,475)	1,583	(25,065)
Ending Balance	4,949,412	4,682,477	4,142,590
Cumulative noncurrent deferred tax assets at end of period	84,207	80,116	82,793
Pension and Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(128,802)	(128,373)	(103,380)
Other comprehensive (loss) earnings before reclassifications, net of Tax	(22,890)	(8,062)	(31,678)
Amounts reclassified from accumulated other comprehensive loss, net of tax	10,187	7,633	6,685
Other comprehensive (loss) earnings, net of tax	(12,703)	(429)	(24,993)
Ending Balance	(141,505)	(128,802)	(128,373)
Cumulative noncurrent deferred tax assets at end of period	84,207	79,938	82,044
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(22)	(1,162)	(264)
Other comprehensive (loss) earnings before reclassifications, net of Tax	(2,052)	1,140	(898)
Other comprehensive (loss) earnings, net of tax	(2,052)	1,140	(898)
Ending Balance	(2,074)	(22)	(1,162)
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(280)	(1,152)	(1,978)
Amounts reclassified from accumulated other comprehensive loss, net of tax	280	872	826
Other comprehensive (loss) earnings, net of tax	280	872	826
Ending Balance		(280)	(1,152)
Cumulative noncurrent deferred tax assets at end of period		178	749
Accumulated Other Comprehensive (Loss) Earnings
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(129,104)	(130,687)	(105,622)
Ending Balance	$ (143,579)	$ (129,104)	$ (130,687)

Accounting Policies - Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Additional interest expense	$ 137,069	$ 91,487	$ 81,677
Tax effect	105,705	(94,457)	181,584
Earnings from Continuing Operations	(10,467)	(8,505)	(7,511)
Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	(10,187)	(7,633)	(6,685)
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	(280)	(872)	(826)
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Special plan termination benefits			764
Settlement charge	2,936	21	115
Prior service credit	(1,971)	(1,430)	(1,609)
Actuarial loss	12,619	13,774	11,575
Tax effect	(3,397)	(4,732)	(4,160)
Earnings from Continuing Operations	10,187	7,633	6,685
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans \| Other Nonoperating Income, Net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications out of accumulated other comprehensive loss before taxes	13,584	12,365	10,845
Reclassification out of Accumulated Other Comprehensive Income \| Unamortized Value of Terminated Forward Starting Interest Rate Swap
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Additional interest expense	458	1,443	1,367
Tax effect	(178)	(571)	(541)
Earnings from Continuing Operations	$ 280	$ 872	$ 826

Accounting Policies - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net earnings attributable to Martin Marietta	$ 469,998	$ 713,342	$ 425,386
Less: Distributed and undistributed earnings attributable to unvested participating securities	806	2,029	1,775
Basic and diluted net earnings attributable to common shareholders attributable to Martin Marietta	$ 469,192	$ 711,313	$ 423,611
Basic weighted-average common shares outstanding	62,895	62,932	63,610
Effect of dilutive employee and director awards	252	285	251
Diluted weighted-average common shares outstanding	63,147	63,217	63,861

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Revenue Recognition - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue Recognition [Line Items]
Performance obligations, description of timing	Performance obligations within paving service agreements are satisfied over time, primarily ranging from one day to two years. For product revenues and freight revenues, customer payment terms are generally 30 days from invoice date. Customer payments for the paving operations are based on a contractual billing schedule and are due 30 days from invoice date.
Product and freight revenues customer payment terms	30 days
Customer payments term based on contractual billing	30 days
Future revenues from unsatisfied performance obligations	$ 78,142,000	$ 66,956,000	$ 74,146,000
Service revenues	4,244,265,000	3,965,594,000	3,818,749,000
Revenue recognized from contract liabilities	6,831,000	8,265,000
Retainage on contracts	7,528,000	9,029,000
COLORADO
Revenue Recognition [Line Items]
Service revenues	$ 219,593,000	$ 245,276,000	$ 216,827,000
Minimum \| Service
Revenue Recognition [Line Items]
Performance obligations, period	1 day
Maximum [Member] \| Service
Revenue Recognition [Line Items]
Performance obligations, period	2 years

Revenue Recognition - Additional Information (Detail 1)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2017-01-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period			1 month
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-01-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		1 month
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period	2 months
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2017-01-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period			33 months
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-01-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		23 months
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period	22 months

Revenue Recognition - Schedule of Company's Total Revenues by Category for each Reportable Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue Recognition [Line Items]
Total	$ 4,244,265	$ 3,965,594	$ 3,818,749
Building Materials Business
Revenue Recognition [Line Items]
Total	3,956,542	3,695,604	3,561,691
Products and Services
Revenue Recognition [Line Items]
Total	3,980,351	3,723,478	3,578,650
Products and Services \| Building Materials Business
Revenue Recognition [Line Items]
Total	3,711,715	3,470,756	3,336,266
Freight
Revenue Recognition [Line Items]
Total	263,914	242,116	240,099
Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	244,827	224,848	225,425
Operating Segments \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	1,223,236	1,053,326	1,017,098
Operating Segments \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	423,382	362,555	321,078
Operating Segments \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	2,309,924	2,279,723	2,223,515
Operating Segments \| Building Materials Business
Revenue Recognition [Line Items]
Total	3,956,542	3,695,604	3,561,691
Operating Segments \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	287,723	269,990	257,058
Operating Segments \| Products and Services \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	1,133,754	982,214	945,193
Operating Segments \| Products and Services \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	409,543	348,675	304,722
Operating Segments \| Products and Services \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	2,168,418	2,139,867	2,086,351
Operating Segments \| Products and Services \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	268,636	252,722	242,384
Operating Segments \| Freight \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	89,482	71,112	71,905
Operating Segments \| Freight \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	13,839	13,880	16,356
Operating Segments \| Freight \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	141,506	139,856	137,164
Operating Segments \| Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	244,827	224,848	225,425
Operating Segments \| Freight \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 19,087	$ 17,268	$ 14,674

Revenue Recognition - Summary of Information About the Company's Contract Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Revenue From Contract With Customer [Abstract]
Costs in excess of billings	$ 1,975	$ 1,310
Billings in excess of costs	$ 6,743	$ 7,204

Goodwill and Other Intangible Assets - Changes in Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Balance at beginning of period	$ 2,160,290	$ 2,159,337
Acquisitions	245,326	230
Goodwill allocated to assets held for sale	(5,571)
Purchase price adjustments		723
Divestitures	(927)
Balance at end of period	2,399,118	2,160,290
Mid-America Group
Goodwill [Line Items]
Balance at beginning of period	281,403	281,403
Acquisitions	150,552
Balance at end of period	431,955	281,403
Southeast Group
Goodwill [Line Items]
Balance at beginning of period	50,346	50,346
Acquisitions	94,774
Divestitures	(927)
Balance at end of period	144,193	50,346
West Group
Goodwill [Line Items]
Balance at beginning of period	1,828,541	1,827,588
Acquisitions		230
Goodwill allocated to assets held for sale	(5,571)
Purchase price adjustments		723
Balance at end of period	$ 1,822,970	$ 1,828,541

Goodwill and Other Intangible Assets - Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 560,360	$ 540,725
Accumulated Amortization	(88,805)	(68,253)
Net Balance	471,555	472,472
Noncompetition agreements
Finite-Lived Intangible Assets [Line Items]
Gross Amount	6,314	6,274
Accumulated Amortization	(6,179)	(6,144)
Net Balance	135	130
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross Amount	65,550	45,955
Accumulated Amortization	(25,575)	(17,551)
Net Balance	39,975	28,404
Operating Permits
Finite-Lived Intangible Assets [Line Items]
Gross Amount	458,951	458,951
Accumulated Amortization	(36,111)	(26,435)
Net Balance	422,840	432,516
Use Rights And Other
Finite-Lived Intangible Assets [Line Items]
Gross Amount	16,745	16,745
Accumulated Amortization	(11,243)	(10,176)
Net Balance	5,502	6,569
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Amount	12,800	12,800
Accumulated Amortization	(9,697)	(7,947)
Net Balance	$ 3,103	$ 4,853

Goodwill and Other Intangible Assets - Intangible Assets Deemed to Indefinite Life and Not Being Amortized (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	$ 29,727	$ 33,877
Operating Permits
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	6,600	6,600
Use Rights Not Subject To Amortization
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	20,282	24,432
Trade names
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	2,845	2,845
Building Materials Business
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	27,162	31,312
Building Materials Business \| Operating Permits
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	6,600	6,600
Building Materials Business \| Use Rights Not Subject To Amortization
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	20,282	24,432
Building Materials Business \| Trade names
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	280	280
Magnesia Specialties
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	2,565	2,565
Magnesia Specialties \| Trade names
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	$ 2,565	$ 2,565

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Other intangibles acquired	$ 21,760
Amortization expense of intangible assets	$ 13,911	$ 14,178	$ 13,922

Goodwill and Other Intangible Assets - Schedule of Acquired Intangibles (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Acquired Finite Lived Intangible Assets [Line Items]
Total subject to amortizationn	$ 20,660
Other intangibles acquired	$ 21,760
Acquired Finite-lived Intangible Assets, Useful Life	12 years
Use Rights Not Subject To Amortization
Acquired Finite Lived Intangible Assets [Line Items]
Acquired intangibles not subject to amortization	$ 1,100
Customer Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Total subject to amortizationn	$ 20,620
Acquired Finite-lived Intangible Assets, Useful Life	12 years
Noncompetition Agreements
Acquired Finite Lived Intangible Assets [Line Items]
Total subject to amortizationn	$ 40
Acquired Finite-lived Intangible Assets, Useful Life	10 years

Goodwill and Other Intangible Assets - Estimated Amortization Expense of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
2019	$ 13,203
2020	13,168
2021	12,462
2022	11,036
2023	10,592
Thereafter	411,094
Net Balance	$ 471,555	$ 472,472

Business Combinations - Additional Information (Detail) - USD ($)		12 Months Ended
	Apr. 27, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Line Items]
Total revenues		$ 4,244,265,000	$ 3,965,594,000	$ 3,818,749,000
Earnings from operations		690,737,000	700,381,000	677,266,000
Acquisition-related expenses		13,479,000	8,638,000	$ 909,000
Bluegrass Materials Company
Business Combinations [Line Items]
Date of acquisition	Apr. 27, 2018
Business acquisition in cash	$ 1,617,357,000
Gain on sale of business			14,785,000
Company acquired voting interest	100.00%
Total revenues		172,015,000
Earnings from operations		32,364,000
Acquisition-related expenses		$ 28,264,000	8,638,000
Increase in cost of sales			18,738,000
Bluegrass Materials Company \| Pro Forma
Business Combinations [Line Items]
Acquisition-related expenses			$ 28,088,000
Bluegrass Materials Company \| Beaver Creek
Business Combinations [Line Items]
Gain on sale of business	$ 0
Bluegrass Materials Company \| Forsyth Quarry
Business Combinations [Line Items]
Gain on sale of business	$ 14,785,000

Business Combinations - Summary of the Preliminary Estimated Fair Values of the Assets Acquired and the Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Apr. 27, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets:
Goodwill	$ 2,399,118		$ 2,160,290	$ 2,159,337
Bluegrass Materials Company
Assets:
Cash and cash equivalents		$ 1,159
Receivables		25,479
Inventory		46,635
Other current assets		1,029
Property, plant and equipment		1,519,289
Intangible assets, other than goodwill		20,150
Goodwill		244,615
Total Assets		1,858,356
Liabilities:
Accounts payable and accrued expenses		17,978
Deferred income tax liabilities, net		214,020
Noncontrolling interest		9,001
Total Liabilities		240,999
Total Consideration		$ 1,617,357

Business Combination - Business Acquisition, Pro Forma Information (Details) - Bluegrass Materials Company - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Total revenues	$ 4,299,673	$ 4,178,627
Net earnings attributable to Martin Marietta	$ 489,526	$ 691,719
Diluted earnings per share	$ 7.75	$ 10.94

Accounts Receivable, Net - Schedule of Accounts Receivable Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Customer receivables	$ 514,094	$ 480,073
Other current receivables	12,535	9,557
Accounts Receivable, gross	526,629	489,630
Less: Allowances	(3,353)	(2,390)
Total	$ 523,276	$ 487,240

Accounts Receivable, Net - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Due from unconsolidated affiliates	$ 2,478	$ 2,819

Inventories, Net - Schedule of Inventories Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished products	$ 615,719	$ 552,999
Products in process and raw materials	66,920	62,761
Supplies and expendable parts	139,566	128,792
Inventories, Gross	822,205	744,552
Less: Allowances	(159,170)	(143,961)
Total	$ 663,035	$ 600,591

Property, Plant and Equipment, Net - Property, Plant and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Land and land improvements	$ 1,089,675	$ 974,622
Mineral reserves and interests	2,506,817	1,162,289
Buildings	162,098	154,564
Machinery and equipment	4,357,705	4,006,619
Construction in progress	178,668	199,973
Gross property, plant and equipment	8,294,963	6,498,067
Less: Accumulated depreciation, depletion and amortization	(3,137,734)	(2,905,254)
Total	$ 5,157,229	$ 3,592,813

Property, Plant and Equipment, Net - Gross Asset Value and Accumulated Amortization for Machinery and Equipment Recorded under Capital Lease (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Machinery and equipment under capital leases	$ 24,931	$ 23,919
Less: Accumulated amortization	(14,524)	(11,243)
Total	$ 10,407	$ 12,676

Property, Plant and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Depreciation, depletion and amortization	$ 326,099	$ 279,808	$ 268,935
Capitalized interest expense	3,017	3,616	$ 3,543
Property, plant and equipment, net	5,157,229	3,592,813
Bahamas And Canada
Property Plant And Equipment [Line Items]
Property, plant and equipment, net	$ 56,235	$ 57,665

Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total	$ 3,120,481	$ 3,027,203
Less: current maturities	(390,042)	(299,909)
Long-term debt	2,730,439	2,727,294
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total	396,398	395,814
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total	124,272	124,180
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Total		299,871
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total	296,939	296,628
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total	494,765	494,352
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total	228,094	228,033
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Total	591,541	591,688
Other Notes
Debt Instrument [Line Items]
Total	256	308
Floating Rate Notes, Due 2019
Debt Instrument [Line Items]
Total	299,260	298,102
Trade Receivable Facility
Debt Instrument [Line Items]
Total	390,000
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Total	$ 298,956	$ 298,227

Long-Term Debt - Long-Term Debt (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 20, 2017	Dec. 31, 2016
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Maturity year	2024
Interest rate on notes	4.25%
Interest rate	4.25%
7% Debentures, Due 2025
Debt Instrument [Line Items]
Maturity year	2025
Interest rate on notes	7.00%
Interest rate	7.12%
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year	2027
Interest rate on notes	3.45%
Interest rate	3.47%
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year	2027
Interest rate on notes	3.50%
Interest rate	3.53%
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Maturity year	2037
Interest rate on notes	6.25%
Interest rate	6.45%
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Maturity year	2047
Interest rate on notes	4.25%
Interest rate	4.27%
Floating Rate Notes, Due 2019
Debt Instrument [Line Items]
Maturity year	2019	2019
Interest rate	3.29%	2.13%
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Maturity year	2020	2020
Interest rate	3.30%	2.10%
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Maturity year	2018
Interest rate on notes	6.60%		6.60%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit Facility interest rate				3.07%

Long-Term Debt - Additional Information (Detail) - USD ($)				12 Months Ended
	Dec. 20, 2017	May 22, 2017	Dec. 05, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Required offer price to repurchase senior notes if change of control repurchase event and downgrade below investment grade credit rating occurs				101.00%
Redemption price percentage of principal amount of notes redeemed		100.00%
Maximum consolidated debt reduction for unrestricted cash and cash equivalents for debt covenant calculation				$ 200,000,000
Outstanding letters of credit				36,081,000
Additional interest expense				458,000	$ 1,443,000	$ 1,367,000
Minimum
Debt Instrument [Line Items]
Reduction of consolidated debt in the debt ratio calculation				$ 50,000,000
Including Acquisition Bridge Debt \| Maximum
Debt Instrument [Line Items]
Debt covenant				3.50
Excluding Acquisition Bridge Debt \| Maximum
Debt Instrument [Line Items]
Debt covenant				3.75
Revolving Facility
Debt Instrument [Line Items]
Credit facility commitment			$ 700,000,000	$ 697,699,000
Senior unsecured revolving facility, maturity period			5 years
Debt instrument maturity period				Dec. 05, 2023
Debt intrument exteded maturity period				1 year
Outstanding letters of credit				$ 2,301,000	2,301,000
Borrowings under revolving facility			$ 700,000,000	697,699,000
Short-term Line of Credit
Debt Instrument [Line Items]
Credit facility commitment					5,000,000
Borrowings under revolving facility					5,000,000
Outstanding borrowing under credit facility				$ 0	$ 0
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Interest rate on notes				4.25%
Maturity year				2024
Senior notes				$ 400,000,000
Maturity date				Jul. 02, 2024
7% Debentures, Due 2025
Debt Instrument [Line Items]
Interest rate on notes				7.00%
Maturity year				2025
Senior notes				$ 125,000,000
Maturity date				Dec. 01, 2025
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Interest rate on notes				3.45%
Maturity year				2027
Senior notes		$ 300,000,000		$ 300,000,000
Debt instrument, redemption description				The 3.45% Senior Notes may be redeemed in whole or in part prior to March 1, 2027 at a make-whole redemption price, or on or after March 1, 2027 at a redemption price equal to 100% of the principal amount of the notes to be redeemed, and in either case plus unpaid interest.
Maturity date				Jun. 01, 2027
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Interest rate on notes				6.25%
Maturity year				2037
Senior notes				$ 230,000,000
Maturity date				May 01, 2037
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Interest rate on notes				3.50%
Maturity year				2027
Senior notes	$ 500,000,000			$ 500,000,000
Maturity date				Dec. 15, 2027
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Interest rate on notes				4.25%
Maturity year				2047
Senior notes	600,000,000			$ 600,000,000
Maturity date				Dec. 15, 2047
Floating Rate Notes, Due 2019
Debt Instrument [Line Items]
Maturity year				2019	2019
Senior notes	$ 300,000,000			$ 300,000,000
Maturity date	Dec. 20, 2019			Dec. 20, 2019
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Maturity year				2020	2020
Senior notes		$ 300,000,000		$ 300,000,000
Maturity date				May 22, 2020
Floating Rate Notes, Due 2020 \| Three-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		0.65%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit facility commitment				$ 400,000,000
Debt instrument maturity period				Sep. 25, 2019
Borrowings under revolving facility				$ 400,000,000
Trade Receivable Facility \| London Interbank Offered Rate(LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate				0.725%
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Interest rate on notes	6.60%			6.60%
Maturity year				2018
Senior notes	$ 300,000,000
Maturity date	Apr. 15, 2018

Long-Term Debt - Schedule of Principal Amount, Effective Interest Rate and Maturity Date for Corporation's Senior Notes (Detail) - USD ($)		12 Months Ended
	Dec. 20, 2017	Dec. 31, 2018	Dec. 31, 2017	May 22, 2017
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Principal Amount		$ 400,000,000
Effective Interest Rate		4.25%
Maturity Date		Jul. 02, 2024
7% Debentures, Due 2025
Debt Instrument [Line Items]
Principal Amount		$ 125,000,000
Effective Interest Rate		7.12%
Maturity Date		Dec. 01, 2025
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Principal Amount		$ 300,000,000		$ 300,000,000
Effective Interest Rate		3.47%
Maturity Date		Jun. 01, 2027
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Principal Amount	$ 500,000,000	$ 500,000,000
Effective Interest Rate		3.53%
Maturity Date		Dec. 15, 2027
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Principal Amount		$ 230,000,000
Effective Interest Rate		6.45%
Maturity Date		May 01, 2037
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Principal Amount	600,000,000	$ 600,000,000
Effective Interest Rate		4.27%
Maturity Date		Dec. 15, 2047
Floating Rate Notes, Due 2019
Debt Instrument [Line Items]
Principal Amount	$ 300,000,000	$ 300,000,000
Effective Interest Rate		3.29%	2.13%
Debt Instrument Effective Interest Rate		Three-month LIBOR + 0.50%
Maturity Date	Dec. 20, 2019	Dec. 20, 2019
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Principal Amount		$ 300,000,000		$ 300,000,000
Effective Interest Rate		3.30%	2.10%
Debt Instrument Effective Interest Rate		Three-month LIBOR + 0.65%
Maturity Date		May 22, 2020

Long-Term Debt - Schedule of Corporation's Long-Term Debt Maturities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2019	$ 390,042
2020	299,015
2021	65
2022	90
2023	299,260
Thereafter	2,132,009
Total	$ 3,120,481	$ 3,027,203

Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Long-term debt, carrying values	$ 3,120,481	$ 3,027,203
Long-term debt, fair values	$ 3,012,224	$ 3,144,902

Income Taxes - Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal income taxes:
Current	$ 15,285	$ 129,236	$ 97,975
Deferred	69,599	(239,304)	68,899
Total federal income taxes	84,884	(110,068)	166,874
State income taxes:
Current	5,986	14,843	15,189
Deferred	14,134	(882)	(1,149)
Total state income taxes	20,120	13,961	14,040
Foreign income taxes:
Current	(1,354)	1,175	1,064
Deferred	2,055	475	(394)
Total foreign income taxes	701	1,650	670
Income tax expense (benefit)	$ 105,705	$ (94,457)	$ 181,584

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Federal statutory corporate income tax rate	21.00%	35.00%	35.00%
Tax benefit for the provisional impact of 2017 Tax Act		$ 258,103,000
Income tax benefit from net operating loss (NOL) carryforwards utilized	$ 5,794,000		$ 11,852,000
Income tax benefits attributable to stock-based compensation			6,792,000
Foreign pretax earnings	$ 5,718,000	$ 10,566,000	$ 3,865,000
Tax deduction, percentage		9.00%	9.00%
Increased net earnings		$ 15,461,000	$ 13,583,000
Increased net earnings, per share		$ 0.25	$ 0.21
Operating loss carryforwards, expiration dates	2037
Deferred tax assets recognized	$ 10,990,000	$ 11,780,000
Deferred tax asset, valuation allowance	$ 8,576,000	10,085,000
Tax refund		3,922,000
Open tax years	2011 2012 2013 2014 2015 2016 2017 2018
Federal Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards, amount	$ 3,219,000
State Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards, amount	168,060,000	197,916,000
Domestic Tax Authority
Income Taxes [Line Items]
Domestic and foreign tax credits, amount	$ 993,000	1,342,000
Domestic tax credits, expiration year	2036
Deferred tax assets recognized	$ 784,000	1,060,000
Deferred tax asset, valuation allowance	28,000	$ 264,000
Tax Year 2017
Income Taxes [Line Items]
Income tax expense for transition tax on undistributed foreign earnings	1,147,000
Income tax expense, write off of deferred tax assets	1,481,000
Income tax benefit of pension funding, inventory and insurance prepayments	$ 21,514,000
Earliest Tax Year
Income Taxes [Line Items]
Expiration date of statute of limitations	2010
Latest Tax Year
Income Taxes [Line Items]
Expiration date of statute of limitations	2013

Income Taxes - Summary of Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory income tax rate	21.00%	35.00%	35.00%
Impact from 2017 Tax Act	(3.30%)	(41.70%)
Effect of statutory depletion	(3.40%)	(5.60%)	(5.40%)
State income taxes, net of federal tax benefit	2.80%	1.50%	1.50%
Stock based compensation	(0.50%)	(1.00%)	(0.10%)
Domestic production deduction		(2.20%)	(2.00%)
Other items	1.70%	(1.30%)	0.90%
Effective income tax rate	18.30%	(15.30%)	29.90%

Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets related to:
Employee benefits		$ 16,059
Inventories	$ 52,618	56,242
Valuation and other reserves	22,359	22,989
Net operating loss carryforwards	10,990	11,780
Accumulated other comprehensive loss	84,207	80,116	$ 82,793
Other items, net	3,052	3,963
Gross deferred tax assets	173,226	191,149
Valuation allowance on deferred tax assets	(8,604)	(10,349)
Total net deferred tax assets	164,622	180,800
Deferred tax liabilities related to:
Property, plant and equipment	(478,329)	(407,400)
Partnerships and joint ventures	(204,315)	(15,617)
Goodwill and other intangibles	(170,538)	(168,506)
Employee benefits	(17,004)
Total deferred tax liabilities	(870,186)	(591,523)
Deferred income taxes, net	$ (705,564)	$ (410,723)

Income Taxes - Schedule of Unrecognized Tax Benefits Excluding Interest Correlative Effects (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning of year	$ 22,367	$ 21,807	$ 18,727
Gross increases – tax positions in prior years	944	1,396	2,401
Gross decreases – tax positions in prior years		(672)	(1,924)
Gross increases – tax positions in current year	1,802	4,961	4,650
Gross decreases – tax positions in current year	(1,013)	(946)	(2,047)
Lapse of statute of limitations		(4,179)
Unrecognized tax benefits at end of year	24,100	22,367	21,807
Amount that, if recognized, would favorably impact the effective tax rate	$ 12,820	$ 10,399	$ 11,603

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 31,624	$ 26,805	$ 22,167
Interest cost	33,209	36,101	35,879
Expected return on assets	(46,011)	(39,759)	(37,699)
Prior service cost (credit)	104	311	350
Actuarial (gain) loss	12,830	14,138	12,074
Transition asset	(1)	(1)	(1)
Settlement charge (credit)	2,936	21	124
Termination benefit charge			764
Total net periodic benefit cost (credit)	34,691	37,616	33,658
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	77	80	85
Interest cost	519	727	863
Prior service cost (credit)	(2,074)	(1,741)	(1,959)
Actuarial (gain) loss	(211)	(364)	(499)
Settlement charge (credit)			(9)
Total net periodic benefit cost (credit)	$ (1,689)	$ (1,298)	$ (1,519)

Retirement Plans, Postretirement and Postemployment Benefits - Net Periodic Benefit Cost Recognized in Comprehensive Earnings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain)	$ (1,700)	$ 1,236	$ 686
Pension
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain)	32,214	13,343	52,028
Net prior service cost (credit)	3
Prior service (cost) credit	(104)	(311)	(350)
Actuarial gain (loss)	(12,830)	(14,138)	(12,074)
Transition asset	1	1	1
Special plan termination benefits			(764)
Settlement (charge) credit	(2,936)	(21)	(124)
Total	16,348	(1,126)	38,717
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net prior service cost (credit)		(3,902)	(1,326)
Prior service (cost) credit	2,074	1,741	1,959
Actuarial gain (loss)	211	364	499
Settlement (charge) credit			9
Total	$ 585	$ (561)	$ 1,827

Retirement Plans, Postretirement and Postemployment Benefits - Net Periodic Benefit Credit or Cost Not Yet Recognized (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Pension
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit) - Gross	$ 14	$ 115
Actuarial (gain) loss - Gross	233,688	217,240
Transition asset - Gross	(5)	(6)
Total - Gross	233,697	217,349
Prior service cost (credit) - Net of tax	9	71
Actuarial (gain) loss - Net of tax	146,588	134,066
Transition asset - Net of tax	(3)	(4)
Total - Net of tax	146,594	134,133
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit) - Gross	(3,747)	(6,314)
Actuarial (gain) loss - Gross	(4,238)	(2,256)
Total - Gross	(7,985)	(8,570)
Prior service cost (credit) - Net of tax	(2,388)	(3,899)
Actuarial (gain) loss - Net of tax	(2,701)	(1,393)
Total - Net of tax	$ (5,089)	$ (5,292)

Retirement Plans, Postretirement and Postemployment Benefits - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for defined benefit pension plans	$ 771,921,000	$ 792,912,000
Combined pension plan and SERP contributions	162,281,000	30,903,000
Corporation's matching obligations	$ 16,545,000	14,893,000	$ 13,235,000
Defined contribution plan name	401(a)
Scenario, Forecast
Defined Benefit Plan Disclosure [Line Items]
Estimated contribution of pension plans				$ 32,022,000
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of pension asset equity securities in mid and large capitalization funds	45.00%
Pension
Defined Benefit Plan Disclosure [Line Items]
Prior service cost, recognized in net periodic benefit cost	$ 8,000
Prior service cost, recognized in net periodic benefit cost - deferred tax asset and liability	2,000
Actuarial gain (loss), recognized in net periodic benefit cost	15,727,000
Actuarial gain (loss), recognized in net periodic benefit cost - deferred tax asset and liability	3,893,000
Transition assets, recognized in net periodic benefit cost	1,000
Combined pension plan and SERP contributions	162,281,000	30,903,000
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Prior service cost, recognized in net periodic benefit cost	762,000
Actuarial gain (loss), recognized in net periodic benefit cost	473,000
Combined pension plan and SERP contributions	950,000	$ 3,385,000
Prior service cost, recognized in net periodic benefit cost - deferred taxes	189,000
Actuarial gain (loss) , recognized in net periodic benefit cost - deferred taxes	$ 117,000
Postretirement Health Care Plans [Member] \| Scenario, Forecast
Defined Benefit Plan Disclosure [Line Items]
Estimated contribution of pension plans				$ 950,000

Retirement Plans, Postretirement and Postemployment Benefits - Change in Projected Benefit Obligation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Actuarial (gain) loss	$ (1,700)	$ 1,236
Pension
Defined Benefit Plan Disclosure [Line Items]
Net projected benefit obligation at beginning of year	879,335	831,849
Service cost	31,624	26,805	$ 22,167
Interest cost	33,209	36,101	35,879
Actuarial (gain) loss	(54,621)	56,675
Plan amendments	3
Gross benefits paid	(41,654)	(72,095)
Net projected benefit obligation at end of year	847,896	879,335	831,849
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net projected benefit obligation at beginning of year	15,347	20,591
Service cost	77	80	85
Interest cost	519	727	863
Participants' contributions	312	3,421
Plan amendments		(3,902)
Gross benefits paid	(1,262)	(6,806)
Net projected benefit obligation at end of year	$ 13,293	$ 15,347	$ 20,591

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Change In Plan Assets (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	$ 638,106,000
Employer contributions	162,281,000	$ 30,903,000
Balance at end of year	717,910,000	638,106,000
Pension
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	638,106,000	596,207,000
Actual return on plan assets, net	(40,823,000)	83,091,000
Employer contributions	162,281,000	30,903,000
Gross benefits paid	(41,654,000)	(72,095,000)
Balance at end of year	717,910,000	638,106,000
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	950,000	3,385,000
Participants' contributions	312,000	3,421,000
Gross benefits paid	$ (1,262,000)	$ (6,806,000)

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Funded Status (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Pension
Defined Benefit Plan Disclosure [Line Items]
Funded status of the plan at end of year	$ (129,986)	$ (241,229)
Accrued benefit cost	(129,986)	(241,229)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Funded status of the plan at end of year	(13,293)	(15,347)
Accrued benefit cost	$ (13,293)	$ (15,347)

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Amounts Recognized on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Current pension and postretirement benefits	$ (8,992)	$ (11,092)
Noncurrent pension, postretirement and postemployment benefits	(120,994)	(230,137)
Net amount recognized at end of year	(129,986)	(241,229)
Current pension and postretirement benefits	(950)	(2,560)
Noncurrent pension, postretirement and postemployment benefits	(12,343)	(12,787)
Net amount recognized at end of year	$ (13,293)	$ (15,347)

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Accumulated Benefit Obligations in Excess of Plan Assets (Detail) - Pension - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 98,729	$ 879,335
Accumulated benefit obligation	85,548	792,912
Fair value of plan assets	$ 560	$ 638,106

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Weighted-Average Assumptions (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.38%	3.76%
Rate of increase in future compensation levels	4.50%	4.50%
Discount rate	3.76%	4.29%	4.67%
Rate of increase in future compensation levels	4.50%	4.50%	4.50%
Expected long-term rate of return on assets	6.75%	6.75%	7.00%
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.15%	3.47%
Discount rate	3.47%	3.78%	4.25%

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Target Assets Allocation (Detail)	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	100.00%
Total		100.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	56.00%
Total	57.00%	57.00%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	30.00%
Total	32.00%	29.00%
Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	4.00%
Total	6.00%	7.00%
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	10.00%
Total	5.00%	7.00%

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Fair Values of Pension Plan Assets by Asset Class and Fair Value Hierarchy Level (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	$ 717,910	$ 638,106
Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	2,864	41
Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	715,046	638,065
Mid-sized to Large Cap
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	196,475	177,497
Mid-sized to Large Cap \| Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	196,475	177,497
Small Cap, International and Emerging Growth Funds
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	210,371	186,272
Small Cap, International and Emerging Growth Funds \| Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	210,371	186,272
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	228,194	182,225
Debt Securities \| Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	228,194	182,225
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	35,553	46,467
Real Estate \| Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	35,553	46,467
Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	44,453	45,604
Hedge Funds \| Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	44,453	45,604
Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	2,864	41
Cash Equivalents \| Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair values of pension plan assets	$ 2,864	$ 41

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Expected Benefit Payments (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Pension
Defined Benefit Plan Disclosure [Line Items]
2019	$ 40,835
2020	42,908
2021	44,237
2022	45,848
2023	47,170
Years 2024 - 2028	260,117
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2019	950
2020	1,492
2021	1,419
2022	1,344
2023	1,254
Years 2024 - 2028	$ 5,809

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Assumed Health Care Cost Trend Rate (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Health care cost trend rate assumed for next year	7.00%	7.00%
Rate to which the cost trend rate gradually declines	5.00%	5.00%
Year the rate reaches the ultimate rate	2023	2022

Retirement Plans, Postretirement and Postemployment Benefits - Schedule of One Percentage-Point Change In Assumed Health Care Cost Trend Rate (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Compensation And Retirement Disclosure [Abstract]
Total service and interest cost components, Increase	$ 25
Postretirement benefit obligation, Increase	640
Total service and interest cost components, Decrease	(22)
Postretirement benefit obligation, Decrease	$ (575)

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended			216 Months Ended	276 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of incentive compensation to acquire shares, maximum	50.00%
Percentage of discount rate to market value on the incentive compensation	20.00%
Company normal retirement age	62 years
Common stock price	$ 171.87			$ 171.87	$ 171.87
Aggregate intrinsic values of options exercised	$ 12,395	$ 13,247	$ 22,571
Aggregate intrinsic values for options outstanding	15,977			$ 15,977	$ 15,977
Aggregate intrinsic values for options exercisable	$ 15,750			$ 15,750	$ 15,750
Awards available for grant	792,000			792,000	792,000
Additional shares issuance under the plan			800,000
Texas Industries Inc.
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options issued to former option holders	821,282
Number of options issued per single option	0.7
Employee stock options expiration period	90 days
Options granted in 2015 and 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock options expiration date	10 years
Options granted prior to 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock options expiration date	8 years
Incentive Compensation Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of stock awards, granted	$ 212.12	$ 208.68	$ 124.41
Aggregate intrinsic values for stock awards	$ 234			$ 234	$ 234
Common stock price	$ 171.87			$ 171.87	$ 171.87
Aggregate intrinsic values of stock awards, distributed	$ 1,662	$ 2,601	$ 1,941
Awards granted	18,180
Restricted Stock - Service Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of stock awards, granted	$ 211.03	$ 213.76	$ 128.48
Awards granted	64,352
Restricted Stock - Performance Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of stock awards, granted	$ 212.12	$ 207.73	$ 124.41
Awards granted	37,138
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic values for stock awards	$ 73,919			$ 73,919	$ 73,919
Aggregate intrinsic values of stock awards, distributed	22,985	$ 15,771	$ 9,738
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Excess tax benefits for stock options exercised	$ 1,741	$ 3,483	$ 4,238
Common stock issued under the plan	0	0	0
Legacy TXI plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards available for grant	0			0	0
Shareholder Value Achievement Plan (1996)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance						250,000
Common stock issued under the plan					42,025
Awards granted				0
Directors' Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	300,000			300,000	300,000
Common stock issued under the plan	3,105	2,132	3,699

Stock-Based Compensation - Summary Information for Restricted Stock Awards and Incentive Compensation Stock Awards (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock - Service Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards, January 1, 2018	314,840
Number of Awards, Awarded	64,352
Number of Awards, Distributed	(88,674)
Number of Awards, Forfeited	(12,371)
Number of Awards, December 31, 2018	278,147	314,840
Weighted-Average Grant-Date Fair Value, January 1, 2018	$ 151.84
Weighted-Average Grant-Date Fair Value, Awarded	211.03	$ 213.76	$ 128.48
Weighted-Average Grant-Date Fair Value, Distributed	159.04
Weighted-Average Grant-Date Fair Value, Forfeited	211.63
Weighted-Average Grant-Date Fair Value, December 31, 2018	$ 158.29	$ 151.84
Restricted Stock - Performance Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards, January 1, 2018	139,999
Number of Awards, Awarded	37,138
Number of Awards, Distributed	(20,219)
Number of Awards, Forfeited	(4,979)
Number of Awards, December 31, 2018	151,939	139,999
Weighted-Average Grant-Date Fair Value, January 1, 2018	$ 150.34
Weighted-Average Grant-Date Fair Value, Awarded	212.12	$ 207.73	124.41
Weighted-Average Grant-Date Fair Value, Distributed	126.01
Weighted-Average Grant-Date Fair Value, Forfeited	182.90
Weighted-Average Grant-Date Fair Value, December 31, 2018	$ 174.74	$ 150.34
Incentive Compensation Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards, January 1, 2018	38,510
Number of Awards, Awarded	18,180
Number of Awards, Distributed	(20,992)
Number of Awards, Forfeited	(322)
Number of Awards, December 31, 2018	35,376	38,510
Weighted-Average Grant-Date Fair Value, January 1, 2018	$ 166.67
Weighted-Average Grant-Date Fair Value, Awarded	212.12	$ 208.68	$ 124.41
Weighted-Average Grant-Date Fair Value, Distributed	138.54
Weighted-Average Grant-Date Fair Value, Forfeited	184.74
Weighted-Average Grant-Date Fair Value, December 31, 2018	$ 206.55	$ 166.67

Stock-Based Compensation - Summary Information for Stock Options (Detail)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Outstanding at January 1, 2018 \| shares	301,958
Number of Options, Exercised \| shares	(89,557)
Number of Options, Terminated \| shares	(2,011)
Number of Options, Outstanding at December 31, 2018 \| shares	210,390
Number of Options, Exercisable at December 31, 2018 \| shares	197,241
Weighted-Average Exercise Price, Outstanding at January 1, 2018 \| $ / shares	$ 91.44
Weighted-Average Exercise Price, Exercised \| $ / shares	81.06
Weighted-Average Exercise Price, Terminated \| $ / shares	83.32
Weighted-Average Exercise Price, Outstanding at December 31, 2018 \| $ / shares	95.93
Weighted-Average Exercise Price, Exercisable at December 31, 2018 \| $ / shares	$ 92.02
Weighted-Average Remaining Contractual Life (years), Outstanding at December 31, 2018	3 years 7 months 6 days
Weighted-Average Remaining Contractual Life (years), Exercisable at December 31, 2018	3 years 4 months 24 days

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized	$ 29,253	$ 30,460	$ 20,481
Unrecognized compensation cost	22,537
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized	242	684	1,646
Unrecognized compensation cost	$ 50
Weighted-average period over which unrecognized compensation cost will be recognized:	4 months 24 days
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized	$ 27,650	28,657	17,747
Unrecognized compensation cost	$ 21,992
Weighted-average period over which unrecognized compensation cost will be recognized:	1 year 7 months 6 days
Incentive Compensation Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized	$ 729	661	442
Unrecognized compensation cost	$ 495
Weighted-average period over which unrecognized compensation cost will be recognized:	1 year 7 months 6 days
Directors' Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized	$ 632	$ 458	$ 646

Stock-Based Compensation - Stock-Based Compensation Expense in Future for Outstanding Awards (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
2019	$ 16,191
2020	5,843
2021	409
2022	94
Total	$ 22,537

Leases - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Leases [Abstract]
Lease expenses for operating lease	$ 122,545	$ 90,731	$ 85,945
Total royalties	52,482	$ 51,827	$ 55,257
Future minimum lease commitments related to contracts of affreightment	$ 172,877

Leases - Future Minimum Lease and Royalty Commitments for All Noncancelable Agreements and Capital Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Capital Leases
2019	$ 3,718
2020	2,695
2021	1,735
2022	1,004
2023	713
Thereafter	3,893
Total	13,758
Less: imputed interest	(2,879)
Present value of minimum lease payments	10,879
Less: current capital lease obligations	(3,249)
Long-term capital lease obligations	7,630
Operating Leases
2019	105,955
2020	70,478
2021	60,382
2022	57,531
2023	56,511
Thereafter	318,147
Total	669,004
Royalty Commitments
2019	14,614
2020	11,364
2021	10,335
2022	9,545
2023	8,109
Thereafter	65,981
Total	$ 119,948

Shareholders' Equity - Additional Information (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock reserved for issuance under stock-based award plans	1,819,000
Stock Repurchased During Period, Shares	521,140	457,742	1,587,987
Common stock remaining under repurchase authorization	14,147,751
Maximum
Class of Stock [Line Items]
Stock repurchase program, shares authorized to be repurchased	20,000,000

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018 USD ($) Bond	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 31, 2018 USD ($)
Commitments and Contingencies [Line Items]
Asset retirement obligation depreciation and accretion	$ 8,015,000	$ 8,682,000	$ 8,823,000
Liability reserve for insurance claims	48,256,000	48,061,000
Outstanding letters of credit	36,081,000
Surety bonds	375,561,000
Balance of top 5 surety bonds	$ 77,603,000
Group of bonds, amount \| Bond	5
Percentage of top 5 surety bonds	21.00%
Due from affiliate	$ 12,710,000
Guarantee of affiliate's obligations	25,000,000			$ 15,500,000
Purchase commitments for property, plant and equipment	225,024,000
Capital expenditures	$ 79,345,000	83,748,000	$ 62,927,000
Percentage of employees represented in labor union	11.00%
Woodville
Commitments and Contingencies [Line Items]
Collective bargaining agreement expiration month year	2022-06
Magnesia Specialties
Commitments and Contingencies [Line Items]
Percentage of employees represented in labor union	100.00%
Collective bargaining agreement expiration month year	2019-08
Capital Addition Purchase Commitments
Commitments and Contingencies [Line Items]
Purchase commitments for property, plant and equipment	$ 118,664,000
Energy And Service Contracts
Commitments and Contingencies [Line Items]
Purchase commitments for property, plant and equipment	106,360,000
Interest-only loan
Commitments and Contingencies [Line Items]
Due from affiliate	$ 6,000,000
Maturity date	Dec. 31, 2022
Revolving Line Of Credit Expires In August 2015
Commitments and Contingencies [Line Items]
Line of credit maturity period	2020-03
Revolving Credit Facility
Commitments and Contingencies [Line Items]
Outstanding letters of credit	$ 2,301,000	$ 2,301,000

Commitments and Contingencies - Changes in Asset Retirement Obligations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Balance at beginning of year	$ 109,653	$ 101,106
Accretion expense	5,074	4,768
Liabilities incurred and liabilities assumed in business combinations	4,692	7,940
Liabilities settled	(2,821)	(309)
Revisions in estimated cash flows	5,206	(3,852)
Balance at end of year	$ 121,804	$ 109,653

Commitments and Contingencies - Contractual Purchase Commitments (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 181,768
2020	14,177
2021	6,264
2022	3,689
2023	1,931
Thereafter	17,195
Total	$ 225,024

Segments - Additional Information (Detail)	12 Months Ended
Segments - Additional Information (Detail)	Dec. 31, 2018 USD ($) Segment
Segment Reporting Information [Line Items]
Reportable business segments \| Segment	3
Asset and portfolio rationalization impairment charges	$ 18,838,000
Building Materials Business West Group
Segment Reporting Information [Line Items]
Asset and portfolio rationalization impairment charges	$ 18,838,000

Segments - Financial Data for Continuing Operations for Company's Reportable Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 4,244,265	$ 3,965,594	$ 3,818,749
Gross profit (loss)	966,577	971,940	911,738
Selling, general and administrative expenses	280,554	262,128	241,606
Earnings (Loss) from operations	690,737	700,381	677,266
Depreciation, depletion and amortization	344,033	297,162	285,253
Assets employed	9,551,419	8,992,511	7,300,905
Total property additions, including the impact of acquisitions	1,925,603	438,621	540,771
Property additions through acquisitions	1,543,160	2,480	133,636
Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	3,956,542	3,695,604	3,561,691
Gross profit (loss)	860,323	875,632	830,636
Selling, general and administrative expenses	182,115	173,731	165,588
Earnings (Loss) from operations	690,780	706,571	679,492
Depreciation, depletion and amortization	315,723	270,324	259,538
Assets employed	9,077,562	7,163,442	6,905,511
Total property additions, including the impact of acquisitions	1,908,315	414,934	521,397
Property additions through acquisitions	1,543,160	2,480	133,636
Operating Segments \| Building Materials Business Mid-America Group
Segment Reporting Information [Line Items]
Total revenues	1,223,236	1,053,326	1,017,098
Gross profit (loss)	366,918	335,394	306,560
Selling, general and administrative expenses	55,775	53,937	52,712
Earnings (Loss) from operations	319,139	284,789	258,422
Depreciation, depletion and amortization	93,639	69,691	64,295
Assets employed	2,788,454	1,532,867	1,406,526
Total property additions, including the impact of acquisitions	1,157,073	139,505	152,014
Property additions through acquisitions	980,236	60	1,524
Operating Segments \| Building Materials Business Southeast Group
Segment Reporting Information [Line Items]
Total revenues	423,382	362,555	321,078
Gross profit (loss)	77,193	74,642	57,286
Selling, general and administrative expenses	18,727	17,144	17,245
Earnings (Loss) from operations	75,840	61,238	41,653
Depreciation, depletion and amortization	41,214	30,780	30,590
Assets employed	1,299,469	616,344	594,967
Total property additions, including the impact of acquisitions	603,078	34,636	30,588
Property additions through acquisitions	561,503
Operating Segments \| Building Materials Business West Group
Segment Reporting Information [Line Items]
Total revenues	2,309,924	2,279,723	2,223,515
Gross profit (loss)	416,212	465,596	466,790
Selling, general and administrative expenses	107,613	102,650	95,631
Earnings (Loss) from operations	295,801	360,544	379,417
Depreciation, depletion and amortization	180,870	169,853	164,653
Assets employed	4,989,639	5,014,231	4,904,018
Total property additions, including the impact of acquisitions	148,164	240,793	338,795
Property additions through acquisitions	1,421	2,420	132,112
Operating Segments \| Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	3,956,542	3,695,604	3,561,691
Gross profit (loss)	860,323	875,632	830,636
Operating Segments \| Magnesia Specialties
Segment Reporting Information [Line Items]
Total revenues	287,723	269,990	257,058
Gross profit (loss)	98,682	89,398	89,603
Selling, general and administrative expenses	9,999	9,537	9,617
Earnings (Loss) from operations	88,063	79,431	79,306
Depreciation, depletion and amortization	10,413	10,070	10,354
Assets employed	156,106	152,257	150,969
Total property additions, including the impact of acquisitions	12,450	11,129	8,944
Corporate
Segment Reporting Information [Line Items]
Gross profit (loss)	7,572	6,910	(8,501)
Selling, general and administrative expenses	88,440	78,860	66,401
Earnings (Loss) from operations	(88,106)	(85,621)	(81,532)
Depreciation, depletion and amortization	17,897	16,768	15,361
Assets employed	317,751	1,676,812	244,425
Total property additions, including the impact of acquisitions	$ 4,838	$ 12,558	$ 10,430

Revenues and Gross Profit - Total Revenues and Gross Profit by Product Line (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Product Information [Line Items]
Total revenues	$ 4,244,265	$ 3,965,594	$ 3,818,749
Gross profit (loss)	966,577	971,940	911,738
Interproduct Revenues
Product Information [Line Items]
Total revenues	(264,237)	(264,012)	(247,111)
Corporate
Product Information [Line Items]
Gross profit (loss)	7,572	6,910	(8,501)
Building Materials Business
Product Information [Line Items]
Total revenues	3,956,542	3,695,604	3,561,691
Gross profit (loss)	860,323	875,632	830,636
Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	3,956,542	3,695,604	3,561,691
Gross profit (loss)	860,323	875,632	830,636
Building Materials Business \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	3,711,715	3,470,756	3,336,266
Gross profit (loss)	860,064	873,030	828,135
Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	287,723	269,990	257,058
Gross profit (loss)	98,682	89,398	89,603
Magnesia Specialties \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	268,636	252,722	242,384
Gross profit (loss)	102,905	94,050	93,987
Aggregates \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	2,355,673	2,134,927	2,058,687
Gross profit (loss)	606,759	599,670	556,131
Cement \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	387,830	371,233	364,139
Gross profit (loss)	126,213	117,021	119,894
Ready Mixed Concrete \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	963,770	936,037	902,678
Gross profit (loss)	74,175	91,646	99,085
Asphalt and Paving \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	268,679	292,571	257,873
Gross profit (loss)	52,917	64,693	53,025
Freight
Product Information [Line Items]
Total revenues	263,914	242,116	240,099
Freight \| Building Materials Business
Product Information [Line Items]
Total revenues	244,827	224,848	225,425
Freight \| Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	244,827	224,848	225,425
Gross profit (loss)	259	2,602	2,501
Freight \| Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	19,087	17,268	14,674
Gross profit (loss)	$ (4,223)	$ (4,652)	$ (4,384)

Revenues and Gross Profit - Domestic and Foreign Total Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Consolidated total revenues	$ 4,244,265	$ 3,965,594	$ 3,818,749
Domestic
Segment Reporting Information [Line Items]
Consolidated total revenues	4,166,339	3,901,323	3,761,651
Foreign
Segment Reporting Information [Line Items]
Consolidated total revenues	$ 77,926	$ 64,271	$ 57,098

Supplemental Cash Flow Information - Components of Change in Other Assets and Liabilities Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Other current and noncurrent assets	$ (34,252)	$ (19,424)	$ 9,171
Accrued salaries, benefits and payroll taxes	12,186	136	16,942
Accrued insurance and other taxes	(1,416)	4,866	(2,688)
Accrued income taxes	(10,336)	(11,044)	(12,523)
Accrued pension, postretirement and postemployment benefits	(133,153)	1,980	(15,955)
Other current and noncurrent liabilities	(12,972)	38,105	(6,053)
Change in other assets and liabilities, net	$ (179,943)	$ 14,619	$ (11,106)

Supplemental Cash Flow Information - Schedule Of Noncash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Accrued liabilities for purchases of property, plant and equipment	$ 66,985	$ 61,644	$ 38,566
Acquisition of assets through capital lease	$ 1,148	811	$ 1,399
Acquisition of assets through asset exchange		2,476
Sale of asset to settle liability		$ 900

Supplemental Cash Flow Information - Supplemental Disclosures of Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 137,239	$ 78,902	$ 73,664
Cash paid for income taxes	$ 28,860	$ 155,771	$ 124,342

Other Operating (Income) and Expenses, Net - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Component Of Other Income And Expense [Line Items]
Other operating (expenses) and income, net	$ 18,193,000	$ (793,000)	$ 8,043,000
Asset and portfolio rationalization charge	18,838,000
Net gains on legal settlements	7,677,000
Gain on sale of assets, excess land	25,271,000
Gain on sale of assets, excess land	39,260,000	19,366,000	$ (410,000)
Nonrecurring repair costs		12,668,000
Noncash portion of asset and portfolio rationalization charge	16,970,000
Cash portion of asset and portfolio rationalization charge	$ 1,868,000
Other Operating (Income) and Expenses, Net
Component Of Other Income And Expense [Line Items]
Gain on sale of assets, excess land		19,366,000
Other Operating (Income) and Expenses, Net \| Executive
Component Of Other Income And Expense [Line Items]
Retirement expense		$ 10,813,000

Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Allowance for doubtful accounts

Valuation And Qualifying Accounts Disclosure [Line Items]

Balance at beginning of period

$ 2,390

$ 6,266

$ 6,940

Charged to costs and expenses

963

Deductions-describe

^[1]

3,876

674

Balance at end of period

3,353

2,390

6,266

Allowance for uncollectible notes receivable

Valuation And Qualifying Accounts Disclosure [Line Items]

Balance at beginning of period

227

437

585

Deductions-describe

^[1]

227

210

148

Balance at end of period

227

437

Inventory valuation allowance

Valuation And Qualifying Accounts Disclosure [Line Items]

Balance at beginning of period

143,961

134,862

130,584

Charged to costs and expenses

36,878

38,488

33,782

Charged to other accounts-describe

^[2]

5,158

118

Deductions-describe

^[3]

26,827

29,389

29,622

Balance at end of period

$ 159,170

$ 143,961

$ 134,862

[1]	Write off of uncollectible accounts and change in estimates.
[2]	Application of reserve policy to acquired inventories.
[3]	Sale of reserved inventory and divestitures.