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Significant Accounting Policies

1.	Significant Accounting Policies

Organization

Martin Marietta Materials, Inc. (the Company or Martin Marietta) 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 vertically-integrated structured markets where the Company has a leading aggregates position. 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.

The Company’s Building Materials business includes three reportable segments: the Mid-America Group, the Southeast Group and the West Group.

BUILDING MATERIALS BUSINESS
Reportable Segments	Mid-America Group	Southeast Group	West Group
Operating Locations	Indiana, Iowa, northern Kansas, Kentucky, Maryland, Minnesota, Missouri, eastern Nebraska, North Carolina, Ohio, Pennsylvania, South Carolina, Virginia, Washington and West Virginia	Alabama, Florida, Georgia, Tennessee, Nova Scotia and the Bahamas	Arkansas, Colorado, southern Kansas, Louisiana, western Nebraska, Nevada, Oklahoma, Texas, Utah and Wyoming

Product Lines	Aggregates	Aggregates	Aggregates, Cement, Ready Mixed Concrete, Asphalt and Paving

The Company has a Magnesia Specialties business with manufacturing facilities in Manistee, Michigan, and Woodville, Ohio. The Magnesia Specialties business produces magnesia-based chemicals products used in industrial, agricultural and environmental applications, and dolomitic lime sold primarily to customers in the steel and mining industries.

Basis of Presentation

The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) for interim financial information and with the instructions to the Quarterly Report on Form 10-Q and in Article 10 of Regulation S-X. Other than the required adoption of Accounting Standards Codification 842 – Leases (ASC 842), the Company has continued to follow the accounting policies set forth in the audited consolidated financial statements and related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. In the opinion of management, the interim consolidated financial information provided herein reflects all adjustments, consisting of normal recurring accruals, necessary for a fair statement of the results of operations, financial position and cash flows for the interim periods. The consolidated results of operations for the three months ended March 31, 2019 are not indicative of the results expected for other interim periods or the full year. The consolidated balance sheet at

December 31, 2018 has been derived from the audited consolidated financial statements at that date but does not include all of the information and notes required by U.S. GAAP for complete financial statements. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

New Accounting Pronouncement

Leases

Effective January 1, 2019, the Company adopted ASC 842, which requires virtually all leases, excluding mineral interest leases, to be recorded as right-of-use (ROU) assets and lease liabilities on the balance sheet and provides guidance on the recognition of lease expense and income. ASC 842 requires the modified retrospective transition approach, applying the new standard to all leases existing at the date of initial application. It further states that an entity may use either 1) its effective date or 2) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Company used the effective date as the date of initial application. As such, financial information and disclosures required under ASC 842 will not be provided for dates and periods prior to January 1, 2019.

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 elected the practical expedients pertaining to the use of hindsight and to land easements. Applying the hindsight practical expedient resulted in longer lease terms for many 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 elected not to separate lease and non-lease components for all underlying asset classes with the exceptions of railcars and fleet vehicle leases. The Company determines lease and non-lease components based on observable information, including rates provided by the lessor.

The adoption of ASC 842 resulted in the recognition of ROU assets and lease liabilities of $502.5 million and $501.6 million, respectively, for operating leases and $10.9 million and $12.1 million, respectively, for finance leases. The adoption did not have a material impact on the Company’s consolidated statement of earnings or consolidated statement of cash flows.

Subsequent to the date of adoption, the Company determines if a contract is or contains a lease at inception of the agreement. Operating and finance leases are recognized as ROU assets and the related obligations are recognized as current or noncurrent liabilities on the Company’s consolidated balance sheets. Leases with an initial lease term of one year or less are not recorded on the balance sheet.

ROU assets, which represent the Company’s right to use an underlying asset, and lease liabilities, which represent the Company’s obligation to make lease payments arising from the lease, are recognized based on the present value of the future lease payments over the lease term at commencement date. The ROU asset also includes any lease payments made at or before commencement date and any initial direct costs incurred and excludes lease incentives. Certain of the Company’s leases contain renewal and/or termination options. The Company recognizes renewal or termination options as part of its ROU assets and lease liabilities when the Company has the unilateral right to renew or terminate and it is reasonably certain these options will be exercised. The Company determines the present value of lease payments based on the implicit rate, which may be explicitly stated in the lease if available or the Company’s estimated collateralized incremental borrowing rate based on the term of the lease. For operating leases, lease expense is recognized on a straight-line basis over the lease term.

Some leases require the Company pay non-lease components, which may include taxes, maintenance, insurance and certain other expenses applicable to the leased property, and are primarily considered variable costs. The Company generally accounts for lease and non-lease components as a single amount. However, for railcars and fleet vehicle leases, the Company separately accounts for the lease and non-lease components.

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss

Consolidated comprehensive earnings/loss and accumulated other comprehensive loss consist of consolidated net earnings or loss; 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 earnings and comprehensive earnings.

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2019		2018
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Other comprehensive earnings, net of tax		3,255		1,619
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	46,108	$	11,642

Comprehensive earnings attributable to noncontrolling interests consist of net earnings and adjustments for the funded status of pension and postretirement benefit plans. For the three months ended March 31, 2019 and 2018, there were no other comprehensive earnings attributable to noncontrolling interests.

Changes in accumulated other comprehensive earnings, net of tax, are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Accumulated Other Comprehensive Loss

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)
Other comprehensive earnings before reclassifications, net of tax		—			497			—			497
Amounts reclassified from accumulated other comprehensive loss, net of tax		2,758			—			—			2,758
Other comprehensive earnings, net of tax		2,758			497			—			3,255
Balance at end of period	$	(138,747	)	$	(1,577	)	$	—		$	(140,324	)

	Three Months Ended March 31, 2018
Balance at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		—			(587	)		—			(587	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		1,996			—			210			2,206
Other comprehensive earnings (loss), net of tax		1,996			(587	)		210			1,619
Balance at end of period	$	(126,806	)	$	(609	)	$	(70	)	$	(127,485	)

Changes in net noncurrent deferred tax assets recorded in accumulated other comprehensive loss are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Net Noncurrent Deferred Tax Assets

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84,207		$	—		$	84,207
Tax effect of other comprehensive earnings		(868	)		—			(868	)
Balance at end of period	$	83,339		$	—		$	83,339

	Three Months Ended March 31, 2018
Balance at beginning of period	$	79,938		$	178		$	80,116
Tax effect of other comprehensive earnings		(658	)		(137	)		(795	)
Balance at end of period	$	79,280		$	41		$	79,321

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2019			2018			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	(188	)	$	(585	)
Actuarial loss		3,814			3,239
		3,626			2,654		Other nonoperating income, net
Tax benefit		(868	)		(658	)	Income tax (benefit) expense
	$	2,758		$	1,996

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	—		$	347		Interest expense
Tax benefit		—			(137	)	Income tax (benefit) expense
	$	—		$	210

Earnings per Common Share

The numerator for basic and diluted earnings per common share is net earnings attributable to Martin Marietta Materials, Inc. reduced by dividends and undistributed earnings attributable to certain of the Company’s stock-based compensation. If there is a net loss, no amount of the undistributed loss is attributed to unvested

participating securities. 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 to be issued to employees and nonemployee members of the Company’s Board of Directors under certain stock-based compensation arrangements if the conversion is dilutive. For the three months ended March 31, 2019 and 2018, the diluted per-share computations reflect the number of common shares outstanding to include the number of additional shares that would have been outstanding if the potentially dilutive common shares had been issued.

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

	Three Months Ended
	March 31,
	2019		2018
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Less: Distributed and undistributed earnings attributable to unvested awards		86		63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	42,767	$	9,960

Basic weighted-average common shares outstanding		62,584		62,957
Effect of dilutive employee and director awards		193		265
Diluted weighted-average common shares outstanding		62,777		63,222

Revenue Recognition

3 Months Ended

Mar. 31, 2019

Revenue Recognition

2.	Revenue Recognition

Total revenues include sales of products and services to customers, net of any discounts or allowances, and freight revenues. Product revenues are recognized when control of the promised good is transferred to the customer, typically when finished products are shipped. Intersegment and interproduct revenues are eliminated in consolidation. Service revenues are derived from the paving business and recognized using the percentage-of-completion method under the revenue-cost approach. Freight revenues reflect delivery arranged by the Company using a third party on behalf of the customer and are recognized consistent with the timing of the product revenues.

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 20 months. 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 March 31, 2019 and 2018 were $149.4 million and $88.1 million, respectively, where the remaining periods to complete these obligations ranged from one month to 21 months and one month to 20 months, respectively.

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

	Three Months Ended
	March 31, 2019
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	230,308	$	18,505	$	248,813
Southeast Group		115,312		3,925		119,237
West Group		463,511		33,320		496,831
Total Building Materials Business		809,131		55,750		864,881
Magnesia Specialties		69,174		4,900		74,074
Total	$	878,305	$	60,650	$	938,955

	Three Months Ended
	March 31, 2018
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	167,890	$	10,891	$	178,781
Southeast Group		77,563		2,676		80,239
West Group		442,983		30,739		473,722
Total Building Materials Business		688,436		44,306		732,742
Magnesia Specialties		64,869		4,393		69,262
Total	$	753,305	$	48,699	$	802,004

Service revenues, which include paving operations located in Colorado, were $9.9 million and $11.1 million for the three months ended March 31, 2019 and 2018, 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:

(Dollars in Thousands)	March 31, 2019		December 31, 2018
Costs in excess of billings	$	2,238	$	1,975
Billings in excess of costs	$	5,814	$	6,743

Revenues recognized from the beginning balance of contract liabilities for the three months ended March 31, 2019 and 2018 were $3.8 million and $4.2 million, 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 $5.4 million and $7.5 million at March 31, 2019 and December 31, 2018.

Warranties. The Company’s construction contracts generally contain warranty provisions typically for a period of nine months to one year after project completion and cover materials, design or workmanship defects. Historically, the Company has not experienced material costs for warranties. The ready mixed concrete product line carries longer warranty periods, 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 project. In total, warranty costs were not material to the Company’s consolidated results of operations for the three months ended March 31, 2019 and March 31, 2018.

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 the accounting standard, the related revenues and costs are presented gross and are included in the consolidated statements of earnings.

Inventories, Net

3 Months Ended

Mar. 31, 2019

Inventories, Net

3.	Inventories, Net

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
Finished products	$	605,785		$	615,719
Products in process and raw materials		63,114			66,920
Supplies and expendable parts		136,792			139,566
		805,691			822,205
Less: Allowances		(159,515	)		(159,170	)
Total	$	646,176		$	663,035

Long-Term Debt

3 Months Ended

Mar. 31, 2019

Financial Instruments Disclosure [Abstract]

4.	Long-Term Debt

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
4.25% Senior Notes, due 2024	$	396,547		$	396,398
7% Debentures, due 2025		124,296			124,272
3.450% Senior Notes, due 2027		297,019			296,939
3.500% Senior Notes, due 2027		494,888			494,765
6.25% Senior Notes, due 2037		228,110			228,094
4.250% Senior Notes, due 2047		591,583			591,541
Floating Rate Notes, due 2019, interest rate of 3.13%, 3.29% and 2.70% at March 31, 2019 and December 31, 2018, respectively		299,446			299,260
Floating Rate Notes, due 2020, interest rate of 3.31%, 3.30% and 2.55% at March 31, 2019 and December 31, 2018, respectively		299,139			298,956
6.60% Senior Notes, due 2018		—			—
Revolving Facility, due 2023, interest rate of 3.59% at March 31, 2019		70,000			—
Trade Receivable Facility, interest rate of 3.21% and 3.07% at March 31, 2019 and December 31, 2018, respectively		360,000			390,000
Other notes		256			256
Total debt		3,161,284			3,120,481
Less: Current maturities of long-term debt and short-term facilities		(360,056	)		(390,042	)
Long-term debt	$	2,801,228		$	2,730,439

The Company, through a wholly-owned special-purpose subsidiary, has a $400 million trade receivable securitization facility (the Trade Receivable Facility). 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, and is limited to the lesser of the facility limit or the borrowing base, as defined. These receivables are originated by the Company and then sold to the wholly-owned special-purpose subsidiary by the Company. 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 London Interbank Offered Rate, or 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, which contains a cross-default provision to the Company’s other debt agreements, matures on September 25, 2019.

The Company has a $700 million five-year senior unsecured revolving facility (the Revolving Facility), which expires on December 5, 2023, 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. 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 Revolving Facility requires the Company’s ratio of consolidated debt-to-consolidated earnings before interest, taxes, depreciation and amortization (EBITDA), as defined by the Revolving Facility, 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 such quarter or the 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 Facility, consolidated debt, including debt for which the Company is a co-borrower, may be reduced by the Company’s unrestricted cash and cash equivalents in excess of $50 million, such reduction not to exceed $200 million, for purposes of the covenant calculation. The Company was in compliance with this Ratio at March 31, 2019.

Available borrowings under the Revolving Facility are reduced by any outstanding letters of credit issued by the Company under the Revolving Facility. The Company had $2.3 million of outstanding letters of credit issued under the Revolving Facility at March 31, 2019 and December 31, 2018.

The Floating Senior Rate Notes due 2019 are classified as noncurrent long-term debt on the consolidated balance sheets as of March 31, 2019 and December 31, 2018 as the Company has the ability and intent to refinance the notes on a long-term basis.

Financial Instruments

3 Months Ended

Mar. 31, 2019

Financial Instruments

5.	Financial Instruments

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

Cash equivalents are placed primarily in money market funds, money market demand deposit accounts and Eurodollar time deposits. The Company’s cash equivalents have original 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. No single customer accounted for 10% or more of consolidated total revenues. The estimated fair values of accounts receivable approximate their carrying amounts due to the short-term nature of the receivables.

Notes receivable are not publicly traded. Management estimates that the fair value of notes receivable approximates the carrying amount due to the short-term nature of the receivables.

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 $3.16 billion and $3.13 billion, respectively, at March 31, 2019 and $3.12 billion and $3.01 billion, respectively, at December 31, 2018. The estimated fair value of the publicly-registered long-term notes was estimated based on Level 2 of the fair value hierarchy using quoted market prices. The estimated fair value of other borrowings approximate their carrying amounts as the interest rates reset periodically.

Income Taxes

3 Months Ended

Mar. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

6.	Income Taxes

The effective income tax rate reflects the effect of federal and state income taxes on earnings and the impact of differences in book and tax accounting arising from the net permanent tax benefits associated with the statutory depletion deduction for mineral reserves. Additionally, for the three months ended March 31, 2019, the effective income tax rate includes a $13.2 million discrete benefit from a change in the tax status of a subsidiary from a partnership to a corporation, contributing to an overall tax benefit of $5.0 million.

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 and comprehensive earnings.

Pension and Postretirement Benefits

3 Months Ended

Mar. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Pension and Postretirement Benefits

7.	Pension and Postretirement Benefits

The estimated components of the recorded net periodic benefit cost (credit) for pension and postretirement benefits are as follows:

	Pension						Postretirement Benefits
	Three Months Ended March 31,
	2019			2018			2019			2018
	(Dollars in Thousands)
Service cost	$	7,872		$	8,148		$	15		$	22
Interest cost		9,395			8,361			131			125
Expected return on assets		(11,966	)		(10,629	)		—			—
Amortization of:
Prior service cost (credit)		2			26			(190	)		(611	)
Actuarial loss (gain)		3,932			3,296			(118	)		(57	)
Net periodic benefit cost (credit)	$	9,235		$	9,202		$	(162	)	$	(521	)

The service cost component of net periodic benefit cost (credit) is included in cost of revenues – products and services and selling, general and administrative expenses. All other components are included in other nonoperating income, net, in the consolidated statements of earnings and comprehensive earnings.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

8.	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, 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.

Borrowing Arrangements with Affiliate

The Company is a co-borrower with an unconsolidated affiliate for a $15.5 million revolving line of credit agreement with BB&T, of which $12.8 million was outstanding as of March 31, 2019 and has a maturity date of March 2020. 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 addition, the Company has a $6.0 million interest-only loan, due December 31, 2022, outstanding from this unconsolidated affiliate as of March 31, 2019 and December 31, 2018. The interest rate is one-month LIBOR plus a current spread of 1.75%.

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 March 31, 2019, the Company was contingently liable for $36.1 million in letters of credit, of which $2.3 million were issued under the Company’s Revolving Facility.

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, 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 June 2022.

Business Segments

3 Months Ended

Mar. 31, 2019

Business Segments

9.	Business Segments

The Building Materials business contains three reportable business segments: Mid-America Group, Southeast Group and West Group. The Company also has a Magnesia Specialties segment. 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 and expenses, net; and taxes on income. Corporate loss from operations primarily includes depreciation on capitalized interest; unallocated expenses for corporate administrative functions; acquisition-related expenses, net; and other nonrecurring income and expenses excluded from the Company’s evaluation of business segment performance and resource allocation. All debt and related interest expense are held at Corporate.

The following table displays selected financial data for the Company’s reportable business segments. The Bluegrass Materials Company (Bluegrass) operations, acquired in April 2018, 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.

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Mid-America Group	$	248,813		$	178,781
Southeast Group		119,237			80,239
West Group		496,831			473,722
Total Building Materials Business		864,881			732,742
Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Products and services revenues:
Mid-America Group	$	230,308		$	167,890
Southeast Group		115,312			77,563
West Group		463,511			442,983
Total Building Materials Business		809,131			688,436
Magnesia Specialties		69,174			64,869
Total	$	878,305		$	753,305

Earnings (Loss) from operations:
Mid-America Group	$	30,955		$	6,167
Southeast Group		21,134			2,041
West Group		19,936			34,951
Total Building Materials Business		72,025			43,159
Magnesia Specialties		22,642			21,237
Corporate		(25,446	)		(25,315	)
Total	$	69,221		$	39,081

	March 31, 2019		December 31, 2018
Assets employed:	(Dollars in thousands)
Mid-America Group	$	2,848,652	$	2,788,454
Southeast Group		1,443,597		1,299,469
West Group		5,280,109		4,989,639
Total Building Materials Business		9,572,358		9,077,562
Magnesia Specialties		170,833		156,106
Corporate		305,216		317,751
Total	$	10,048,407	$	9,551,419

Revenues and Gross Profit

3 Months Ended

Mar. 31, 2019

Revenues and Gross Profit

10.	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 reside in the West Group. The following table, which is reconciled to consolidated amounts, provides total revenues and gross profit by product line.

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Building Materials Business:
Products and services:
Aggregates	$	541,473		$	425,016
Cement		99,017			89,183
Ready mixed concrete		211,156			218,537
Asphalt and paving services		15,846			16,365
Less: interproduct revenues		(58,361	)		(60,665	)
Products and services		809,131			688,436
Freight		55,750			44,306
Total Building Materials Business		864,881			732,742
Magnesia Specialties:
Products and services		69,174			64,869
Freight		4,900			4,393
Total Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Gross profit (loss):
Building Materials Business:
Products and services:
Aggregates	$	97,562		$	53,002
Cement		13,779			23,734
Ready mixed concrete		14,492			15,641
Asphalt and paving services		(7,829	)		(7,639	)
Products and services		118,004			84,738
Freight		(165	)		(119	)
Total Building Materials Business		117,839			84,619
Magnesia Specialties:
Products and services		26,607			25,063
Freight		(1,065	)		(1,174	)
Total Magnesia Specialties		25,542			23,889
Corporate		(474	)		1,884
Total	$	142,907		$	110,392

Leases

3 Months Ended

Mar. 31, 2019

Leases

11.

Leases

The Company has leases primarily for equipment, railcars, fleet vehicles, office space, land and information technology equipment and software. The Company’s leases have remaining lease terms of one year to 54 years, some of which may include options to extend the leases for up to 30 years, and some of which may include options to terminate the leases within one year.

Certain of the Company’s lease agreements include payments based upon variable rates, including but not limited to hours used, tonnage processed and factors related to indices. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants.

The components of lease cost are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating lease cost	$	19,966
Finance lease cost:
Amortization of right-of-use assets		935
Interest on lease liabilities		148
Variable lease cost		4,667
Short-term lease cost		8,118
Total lease cost	$	33,834

The balance sheet classifications of operating and finance leases are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating Leases:
Operating lease right-of-use assets	$	498,233

Current operating lease liabilities	$	50,776
Noncurrent operating lease liabilities		446,128
Total operating lease liabilities	$	496,904

Finance Leases:
Property, plant and equipment	$	11,143
Accumulated depreciation		(935	)
Property, plant and equipment, net	$	10,208

Other current liabilities	$	3,456
Other noncurrent liabilities		7,862
Total finance lease liabilities	$	11,318

The estimated incremental borrowing rate range used was 3.5% to 5.5%. Weighted-average remaining lease terms and discount rates are as follows:

	March 31, 2019
Weighted-average remaining lease term (years):
Operating leases		15.0
Finance leases		8.2

Weighted-average discount rate:
Operating leases		4.3	%
Finance leases		5.1	%

Future lease payments under leases as of March 31, 2019 are as follows:

	Operating			Finance
	Leases			Leases
	(Dollars in Thousands)
2019	$	53,014		$	2,956
2020		63,870			3,243
2021		52,674			1,951
2022		48,376			1,094
2023		45,912			779
Thereafter		429,013			4,176
Total lease payments		692,859			14,199
Less: imputed interest		(195,593	)		(2,881	)
Present value of lease payments		497,266			11,318
Less: current lease obligations		(50,776	)		(3,456	)
Total long-term lease obligations	$	446,490		$	7,862

As of March 31, 2019, the Company has additional operating leases, primarily for equipment and land, that have not yet commenced of $1.7 million. These operating leases will commence in fiscal year 2019 with lease terms of two years to ten years. These leases are included in the preceding table.

Other lease information is as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$	19,512
Operating cash flows used for finance leases	$	148
Financing cash flows used for finance leases	$	951
Right-of-use assets obtained in exchange for new operating lease liabilities	$	16,924
Right-of-use assets obtained in exchange for new finance lease liabilities	$	217

Lease disclosures for the full year December 31, 2018, as reported:

Total lease expense for operating leases was $122.5 million for the year ended December 31, 2018. Total royalties, principally for leased properties, were $52.5 million, for the year ended December 31, 2018. 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 were as follows:

	Capital Leases			Operating Leases		Royalty Commitments
	(Dollars in Thousands)
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

Supplemental Cash Flow Information

3 Months Ended

Mar. 31, 2019

Supplemental Cash Flow Information

12.	Supplemental Cash Flow Information

Noncash investing and financing activities are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	20,629	$	35,639
Acquisition of assets through swap	$	1,114	$	—
Note receivable issued in connection with sale of property, plant and equipment	$	1,272	$	—
Acquisition of assets through capital lease	$	—	$	192

Supplemental disclosures of cash flow information are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Cash paid for interest	$	17,750	$	12,458
Cash paid for (refund of) income taxes	$	3,905	$	(7,527	)

Bluegrass Acquisition

3 Months Ended

Mar. 31, 2019

Bluegrass Acquisition

13.	Bluegrass Acquisition

In April 2018, the Company acquired Bluegrass, the largest privately-held, pure-play aggregates company in the United States for $1.62 billion. These operations complement the Company’s existing southeastern footprint in its Mid-America and Southeast Groups and provide new growth platforms within Maryland and Kentucky.

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 March 31, 2019. The following is a summary of the preliminary estimated fair values of the assets acquired and the liabilities assumed (dollars in thousands):

Assets:
Cash	$	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		242,981
Total assets		1,856,722

Liabilities:
Accounts payable and accrued expenses		17,978
Deferred income tax liabilities, net		212,386
Noncontrolling interest		9,001
Total liabilities		239,365

Total consideration	$	1,617,357

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. 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, expenses related to the acquisition would be reflected in the pro forma results for the year ended December 31, 2017. The pro forma financial 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 2017.

The following presents pro forma results for the quarter ended March 31, 2018:

(Dollars in Thousands, except per share data)
Total revenues	$	840,909
Net earnings attributable to Martin Marietta	$	2,988
Diluted EPS	$	0.05

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2019

New Accounting Pronouncement

Organization

The Company’s Building Materials business includes three reportable segments: the Mid-America Group, the Southeast Group and the West Group.

BUILDING MATERIALS BUSINESS
Reportable Segments	Mid-America Group	Southeast Group	West Group
Operating Locations	Indiana, Iowa, northern Kansas, Kentucky, Maryland, Minnesota, Missouri, eastern Nebraska, North Carolina, Ohio, Pennsylvania, South Carolina, Virginia, Washington and West Virginia	Alabama, Florida, Georgia, Tennessee, Nova Scotia and the Bahamas	Arkansas, Colorado, southern Kansas, Louisiana, western Nebraska, Nevada, Oklahoma, Texas, Utah and Wyoming

Product Lines	Aggregates	Aggregates	Aggregates, Cement, Ready Mixed Concrete, Asphalt and Paving

Basis of Presentation

Leases

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2019		2018
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Other comprehensive earnings, net of tax		3,255		1,619
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	46,108	$	11,642

Changes in accumulated other comprehensive earnings, net of tax, are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Accumulated Other Comprehensive Loss

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)
Other comprehensive earnings before reclassifications, net of tax		—			497			—			497
Amounts reclassified from accumulated other comprehensive loss, net of tax		2,758			—			—			2,758
Other comprehensive earnings, net of tax		2,758			497			—			3,255
Balance at end of period	$	(138,747	)	$	(1,577	)	$	—		$	(140,324	)

	Three Months Ended March 31, 2018
Balance at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		—			(587	)		—			(587	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		1,996			—			210			2,206
Other comprehensive earnings (loss), net of tax		1,996			(587	)		210			1,619
Balance at end of period	$	(126,806	)	$	(609	)	$	(70	)	$	(127,485	)

Changes in net noncurrent deferred tax assets recorded in accumulated other comprehensive loss are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Net Noncurrent Deferred Tax Assets

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84,207		$	—		$	84,207
Tax effect of other comprehensive earnings		(868	)		—			(868	)
Balance at end of period	$	83,339		$	—		$	83,339

	Three Months Ended March 31, 2018
Balance at beginning of period	$	79,938		$	178		$	80,116
Tax effect of other comprehensive earnings		(658	)		(137	)		(795	)
Balance at end of period	$	79,280		$	41		$	79,321

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2019			2018			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	(188	)	$	(585	)
Actuarial loss		3,814			3,239
		3,626			2,654		Other nonoperating income, net
Tax benefit		(868	)		(658	)	Income tax (benefit) expense
	$	2,758		$	1,996

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	—		$	347		Interest expense
Tax benefit		—			(137	)	Income tax (benefit) expense
	$	—		$	210

Earnings per Common Share

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

	Three Months Ended
	March 31,
	2019		2018
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Less: Distributed and undistributed earnings attributable to unvested awards		86		63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	42,767	$	9,960

Basic weighted-average common shares outstanding		62,584		62,957
Effect of dilutive employee and director awards		193		265
Diluted weighted-average common shares outstanding		62,777		63,222

Policy Elections

Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2019

Changes in Accumulated Other Comprehensive Earnings Net of Tax

Changes in accumulated other comprehensive earnings, net of tax, are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Accumulated Other Comprehensive Loss

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)
Other comprehensive earnings before reclassifications, net of tax		—			497			—			497
Amounts reclassified from accumulated other comprehensive loss, net of tax		2,758			—			—			2,758
Other comprehensive earnings, net of tax		2,758			497			—			3,255
Balance at end of period	$	(138,747	)	$	(1,577	)	$	—		$	(140,324	)

	Three Months Ended March 31, 2018
Balance at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		—			(587	)		—			(587	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		1,996			—			210			2,206
Other comprehensive earnings (loss), net of tax		1,996			(587	)		210			1,619
Balance at end of period	$	(126,806	)	$	(609	)	$	(70	)	$	(127,485	)

Noncurrent Deferred Tax Assets Recorded In Accumulated Other Comprehensive Loss

Changes in net noncurrent deferred tax assets recorded in accumulated other comprehensive loss are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Net Noncurrent Deferred Tax Assets

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84,207		$	—		$	84,207
Tax effect of other comprehensive earnings		(868	)		—			(868	)
Balance at end of period	$	83,339		$	—		$	83,339

	Three Months Ended March 31, 2018
Balance at beginning of period	$	79,938		$	178		$	80,116
Tax effect of other comprehensive earnings		(658	)		(137	)		(795	)
Balance at end of period	$	79,280		$	41		$	79,321

Reclassification Out of Accumulated Other Comprehensive Loss

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2019			2018			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	(188	)	$	(585	)
Actuarial loss		3,814			3,239
		3,626			2,654		Other nonoperating income, net
Tax benefit		(868	)		(658	)	Income tax (benefit) expense
	$	2,758		$	1,996

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	—		$	347		Interest expense
Tax benefit		—			(137	)	Income tax (benefit) expense
	$	—		$	210

Basic and Diluted Earnings Per Common Share

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

	Three Months Ended
	March 31,
	2019		2018
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Less: Distributed and undistributed earnings attributable to unvested awards		86		63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	42,767	$	9,960

Basic weighted-average common shares outstanding		62,584		62,957
Effect of dilutive employee and director awards		193		265
Diluted weighted-average common shares outstanding		62,777		63,222

Parent

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2019		2018
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Other comprehensive earnings, net of tax		3,255		1,619
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	46,108	$	11,642

Noncontrolling Interests

Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2019

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:

	Three Months Ended
	March 31, 2019
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	230,308	$	18,505	$	248,813
Southeast Group		115,312		3,925		119,237
West Group		463,511		33,320		496,831
Total Building Materials Business		809,131		55,750		864,881
Magnesia Specialties		69,174		4,900		74,074
Total	$	878,305	$	60,650	$	938,955

	Three Months Ended
	March 31, 2018
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	167,890	$	10,891	$	178,781
Southeast Group		77,563		2,676		80,239
West Group		442,983		30,739		473,722
Total Building Materials Business		688,436		44,306		732,742
Magnesia Specialties		64,869		4,393		69,262
Total	$	753,305	$	48,699	$	802,004

Summary of Information About the Company's Contract Balances

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

(Dollars in Thousands)	March 31, 2019		December 31, 2018
Costs in excess of billings	$	2,238	$	1,975
Billings in excess of costs	$	5,814	$	6,743

Inventories, Net (Tables)

3 Months Ended

Mar. 31, 2019

Schedule of Inventories Net

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
Finished products	$	605,785		$	615,719
Products in process and raw materials		63,114			66,920
Supplies and expendable parts		136,792			139,566
		805,691			822,205
Less: Allowances		(159,515	)		(159,170	)
Total	$	646,176		$	663,035

Long-Term Debt (Tables)

3 Months Ended

Mar. 31, 2019

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
4.25% Senior Notes, due 2024	$	396,547		$	396,398
7% Debentures, due 2025		124,296			124,272
3.450% Senior Notes, due 2027		297,019			296,939
3.500% Senior Notes, due 2027		494,888			494,765
6.25% Senior Notes, due 2037		228,110			228,094
4.250% Senior Notes, due 2047		591,583			591,541
Floating Rate Notes, due 2019, interest rate of 3.13%, 3.29% and 2.70% at March 31, 2019 and December 31, 2018, respectively		299,446			299,260
Floating Rate Notes, due 2020, interest rate of 3.31%, 3.30% and 2.55% at March 31, 2019 and December 31, 2018, respectively		299,139			298,956
6.60% Senior Notes, due 2018		—			—
Revolving Facility, due 2023, interest rate of 3.59% at March 31, 2019		70,000			—
Trade Receivable Facility, interest rate of 3.21% and 3.07% at March 31, 2019 and December 31, 2018, respectively		360,000			390,000
Other notes		256			256
Total debt		3,161,284			3,120,481
Less: Current maturities of long-term debt and short-term facilities		(360,056	)		(390,042	)
Long-term debt	$	2,801,228		$	2,730,439

Compensation And Retirement Disclosure [Abstract]

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

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+ Details

Pension and Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2019

Schedule of Components of Net Periodic Benefit Cost (Credit)

The estimated components of the recorded net periodic benefit cost (credit) for pension and postretirement benefits are as follows:

	Pension						Postretirement Benefits
	Three Months Ended March 31,
	2019			2018			2019			2018
	(Dollars in Thousands)
Service cost	$	7,872		$	8,148		$	15		$	22
Interest cost		9,395			8,361			131			125
Expected return on assets		(11,966	)		(10,629	)		—			—
Amortization of:
Prior service cost (credit)		2			26			(190	)		(611	)
Actuarial loss (gain)		3,932			3,296			(118	)		(57	)
Net periodic benefit cost (credit)	$	9,235		$	9,202		$	(162	)	$	(521	)

Business Segments (Tables)

3 Months Ended

Mar. 31, 2019

Financial Data for Continuing Operation for Company's Reportable Business Segments

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Mid-America Group	$	248,813		$	178,781
Southeast Group		119,237			80,239
West Group		496,831			473,722
Total Building Materials Business		864,881			732,742
Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Products and services revenues:
Mid-America Group	$	230,308		$	167,890
Southeast Group		115,312			77,563
West Group		463,511			442,983
Total Building Materials Business		809,131			688,436
Magnesia Specialties		69,174			64,869
Total	$	878,305		$	753,305

Earnings (Loss) from operations:
Mid-America Group	$	30,955		$	6,167
Southeast Group		21,134			2,041
West Group		19,936			34,951
Total Building Materials Business		72,025			43,159
Magnesia Specialties		22,642			21,237
Corporate		(25,446	)		(25,315	)
Total	$	69,221		$	39,081

	March 31, 2019		December 31, 2018
Assets employed:	(Dollars in thousands)
Mid-America Group	$	2,848,652	$	2,788,454
Southeast Group		1,443,597		1,299,469
West Group		5,280,109		4,989,639
Total Building Materials Business		9,572,358		9,077,562
Magnesia Specialties		170,833		156,106
Corporate		305,216		317,751
Total	$	10,048,407	$	9,551,419

Supplemental Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2019

Schedule Of Other Significant Noncash Transactions

Noncash investing and financing activities are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	20,629	$	35,639
Acquisition of assets through swap	$	1,114	$	—
Note receivable issued in connection with sale of property, plant and equipment	$	1,272	$	—
Acquisition of assets through capital lease	$	—	$	192

Supplemental Disclosures of Cash Flow Information

Supplemental disclosures of cash flow information are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Cash paid for interest	$	17,750	$	12,458
Cash paid for (refund of) income taxes	$	3,905	$	(7,527	)

Revenues and Gross Profit (Tables)

3 Months Ended

Mar. 31, 2019

Total Revenues and Gross Profit by Product Line

The following table, which is reconciled to consolidated amounts, provides total revenues and gross profit by product line.

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Building Materials Business:
Products and services:
Aggregates	$	541,473		$	425,016
Cement		99,017			89,183
Ready mixed concrete		211,156			218,537
Asphalt and paving services		15,846			16,365
Less: interproduct revenues		(58,361	)		(60,665	)
Products and services		809,131			688,436
Freight		55,750			44,306
Total Building Materials Business		864,881			732,742
Magnesia Specialties:
Products and services		69,174			64,869
Freight		4,900			4,393
Total Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Gross profit (loss):
Building Materials Business:
Products and services:
Aggregates	$	97,562		$	53,002
Cement		13,779			23,734
Ready mixed concrete		14,492			15,641
Asphalt and paving services		(7,829	)		(7,639	)
Products and services		118,004			84,738
Freight		(165	)		(119	)
Total Building Materials Business		117,839			84,619
Magnesia Specialties:
Products and services		26,607			25,063
Freight		(1,065	)		(1,174	)
Total Magnesia Specialties		25,542			23,889
Corporate		(474	)		1,884
Total	$	142,907		$	110,392

Leases (Tables)

3 Months Ended

Mar. 31, 2019

Summary of Components of Lease Cost

The components of lease cost are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating lease cost	$	19,966
Finance lease cost:
Amortization of right-of-use assets		935
Interest on lease liabilities		148
Variable lease cost		4,667
Short-term lease cost		8,118
Total lease cost	$	33,834

Summary of Balance Sheet Classifications of Operating and Finance Leases

The balance sheet classifications of operating and finance leases are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating Leases:
Operating lease right-of-use assets	$	498,233

Current operating lease liabilities	$	50,776
Noncurrent operating lease liabilities		446,128
Total operating lease liabilities	$	496,904

Finance Leases:
Property, plant and equipment	$	11,143
Accumulated depreciation		(935	)
Property, plant and equipment, net	$	10,208

Other current liabilities	$	3,456
Other noncurrent liabilities		7,862
Total finance lease liabilities	$	11,318

Summary of Weighted-average Remaining Lease Terms and Discount Rates

Weighted-average remaining lease terms and discount rates are as follows:

	March 31, 2019
Weighted-average remaining lease term (years):
Operating leases		15.0
Finance leases		8.2

Weighted-average discount rate:
Operating leases		4.3	%
Finance leases		5.1	%

Summary of Future Lease Payments under Noncancellable Leases

Future lease payments under leases as of March 31, 2019 are as follows:

	Operating			Finance
	Leases			Leases
	(Dollars in Thousands)
2019	$	53,014		$	2,956
2020		63,870			3,243
2021		52,674			1,951
2022		48,376			1,094
2023		45,912			779
Thereafter		429,013			4,176
Total lease payments		692,859			14,199
Less: imputed interest		(195,593	)		(2,881	)
Present value of lease payments		497,266			11,318
Less: current lease obligations		(50,776	)		(3,456	)
Total long-term lease obligations	$	446,490		$	7,862

Summary of Other Leases Information

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$	19,512
Operating cash flows used for finance leases	$	148
Financing cash flows used for finance leases	$	951
Right-of-use assets obtained in exchange for new operating lease liabilities	$	16,924
Right-of-use assets obtained in exchange for new finance lease liabilities	$	217

Summary of Future Minimum Lease and Royalty Commitments for all Noncancelable Agreements and Capital Lease Obligations

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

	Capital Leases			Operating Leases		Royalty Commitments
	(Dollars in Thousands)
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

Bluegrass Acquisition (Tables)

3 Months Ended

Mar. 31, 2019

Summary of 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 (dollars in thousands):

Assets:
Cash	$	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		242,981
Total assets		1,856,722

Liabilities:
Accounts payable and accrued expenses		17,978
Deferred income tax liabilities, net		212,386
Noncontrolling interest		9,001
Total liabilities		239,365

Total consideration	$	1,617,357

Business Acquisition, Pro Forma Information

The following presents pro forma results for the quarter ended March 31, 2018:

(Dollars in Thousands, except per share data)
Total revenues	$	840,909
Net earnings attributable to Martin Marietta	$	2,988
Diluted EPS	$	0.05

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019 USD ($) Facility State Segment	Mar. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Significant Accounting Policies [Line Items]
Number of states with aggregates business sales by destination \| State	31
Number of reportable segments \| Segment	3
Operating lease, right of use asset	$ 498,233,000
Operating lease, liability	496,904,000
Finance leases, liability	11,318,000			$ 10,879,000
Other comprehensive earnings attributable to noncontrolling interests	$ 0	$ 0
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease, right of use asset			$ 502,500,000
Operating lease, liability			501,600,000
Finance leases, right of use asset			10,900,000
Finance leases, liability			$ 12,100,000
Minimum
Significant Accounting Policies [Line Items]
Number of quarries and yards \| Facility	300

Significant Accounting Policies - Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 42,853	$ 10,023
Other comprehensive earnings, net of tax	3,255	1,619
Earnings attributable to Martin Marietta Materials, Inc.	$ 46,108	$ 11,642

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

Significant Accounting Policies - Changes in Accumulated Other Comprehensive Earnings Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 4,949,412	$ 4,682,477
Other comprehensive earnings (loss) before reclassifications, net of tax	497	(587)
Amounts reclassified from accumulated other comprehensive loss, net of tax	2,758	2,206
Other comprehensive earnings (loss), net of tax	3,255	1,619
Ending Balance	4,975,496	4,679,830
Pension and Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(141,505)	(128,802)
Amounts reclassified from accumulated other comprehensive loss, net of tax	2,758	1,996
Other comprehensive earnings (loss), net of tax	2,758	1,996
Ending Balance	(138,747)	(126,806)
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,074)	(22)
Other comprehensive earnings (loss) before reclassifications, net of tax	497	(587)
Other comprehensive earnings (loss), net of tax	497	(587)
Ending Balance	(1,577)	(609)
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(280)
Amounts reclassified from accumulated other comprehensive loss, net of tax		210
Other comprehensive earnings (loss), net of tax		210
Ending Balance		(70)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(143,579)	(129,104)
Ending Balance	$ (140,324)	$ (127,485)

Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 84,207	$ 79,938
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans	(868)	(658)
Balance at end of period, Pension and Postretirement Benefit Plans	83,339	79,280
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap		178
Tax effect of other comprehensive earnings, Unamortized Value of Terminated Forward Starting Interest Rate Swap		(137)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap		41
Balance at beginning of period, Net Noncurrent Deferred Tax Assets	84,207	80,116
Tax effect of other comprehensive earnings, Net Noncurrent Deferred Tax Assets	(868)	(795)
Balance at end of period, Net Noncurrent Deferred Tax Assets	$ 83,339	$ 79,321

Significant Accounting Policies - Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Additional interest expense	$ 32,948	$ 35,087
Tax benefit	(4,991)	2,457
Earnings from Continuing Operations	2,758	2,206
Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	2,758	1,996
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations		210
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit	(188)	(585)
Actuarial loss	3,814	3,239
Tax benefit	(868)	(658)
Earnings from Continuing Operations	2,758	1,996
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	$ 3,626	2,654
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		347
Tax benefit		(137)
Earnings from Continuing Operations		$ 210

Significant Accounting Policies - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 42,853	$ 10,023
Less: Distributed and undistributed earnings attributable to unvested awards	86	63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 42,767	$ 9,960
Basic weighted-average common shares outstanding	62,584	62,957
Effect of dilutive employee and director awards	193	265
Diluted weighted-average common shares outstanding	62,777	63,222

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

Revenue Recognition - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
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 20 months. 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 terms based on contractual billing	30 days
Future revenues from unsatisfied performance obligations	$ 149,400	$ 88,100
Service revenues	938,955	802,004
Revenue recognized from contract liabilities	3,800	4,200
Retainage on contracts	5,400		$ 7,500
COLORADO
Revenue Recognition [Line Items]
Service revenues	$ 9,900	$ 11,100
Minimum
Revenue Recognition [Line Items]
Warranty term	9 months
Minimum \| Service
Revenue Recognition [Line Items]
Performance obligations, period	1 day
Maximum
Revenue Recognition [Line Items]
Warranty term	1 year
Maximum \| Service
Revenue Recognition [Line Items]
Performance obligations, period	20 months

Revenue Recognition - Additional Information (Detail 1)	Mar. 31, 2019	Mar. 31, 2018
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		1 month
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period	1 month
Maximum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		20 months
Maximum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period	21 months

Revenue Recognition - Schedule of Company's Total Revenues by Category for each Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue Recognition [Line Items]
Total	$ 938,955	$ 802,004
Building Materials Business
Revenue Recognition [Line Items]
Total	864,881	732,742
Products and Services
Revenue Recognition [Line Items]
Total	878,305	753,305
Products and Services \| Building Materials Business
Revenue Recognition [Line Items]
Total	809,131	688,436
Freight
Revenue Recognition [Line Items]
Total	60,650	48,699
Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	55,750	44,306
Operating Segments \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	248,813	178,781
Operating Segments \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	119,237	80,239
Operating Segments \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	496,831	473,722
Operating Segments \| Building Materials Business
Revenue Recognition [Line Items]
Total	864,881	732,742
Operating Segments \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	74,074	69,262
Operating Segments \| Products and Services \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	230,308	167,890
Operating Segments \| Products and Services \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	115,312	77,563
Operating Segments \| Products and Services \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	463,511	442,983
Operating Segments \| Products and Services \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	69,174	64,869
Operating Segments \| Freight \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	18,505	10,891
Operating Segments \| Freight \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	3,925	2,676
Operating Segments \| Freight \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	33,320	30,739
Operating Segments \| Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	55,750	44,306
Operating Segments \| Freight \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 4,900	$ 4,393

Revenue Recognition - Summary of Information About the Company's Contract Balances (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Costs in excess of billings	$ 2,238	$ 1,975
Billings in excess of costs	$ 5,814	$ 6,743

Inventories, Net - Schedule of Inventories Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Finished products	$ 605,785	$ 615,719
Products in process and raw materials	63,114	66,920
Supplies and expendable parts	136,792	139,566
Inventories, Gross	805,691	822,205
Less: Allowances	(159,515)	(159,170)
Total	$ 646,176	$ 663,035

Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total debt	$ 3,161,284	$ 3,120,481
Less: Current maturities of long-term debt and short-term facilities	(360,056)	(390,042)
Long-term debt	2,801,228	2,730,439
Revolving Facility, Due 2023
Debt Instrument [Line Items]
Total debt	70,000
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	396,547	396,398
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total debt	124,296	124,272
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	297,019	296,939
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	494,888	494,765
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total debt	228,110	228,094
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Total debt	591,583	591,541
Floating Rate Notes, Due 2019
Debt Instrument [Line Items]
Total debt	299,446	299,260
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Total debt	299,139	298,956
Other Notes
Debt Instrument [Line Items]
Total debt	256	256
Trade Receivable Facility
Debt Instrument [Line Items]
Total debt	$ 360,000	$ 390,000

Long-Term Debt - Long-Term Debt (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Revolving Facility, Due 2022
Debt Instrument [Line Items]
Maturity year	2023
Credit Facility interest rate	3.59%
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Maturity year	2024
Interest rate on notes	4.25%
7% Debentures, Due 2025
Debt Instrument [Line Items]
Maturity year	2025
Interest rate on notes	7.00%
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year	2027
Interest rate on notes	3.45%
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year	2027
Interest rate on notes	3.50%
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Maturity year	2037
Interest rate on notes	6.25%
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Maturity year	2047
Interest rate on notes	4.25%
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Maturity year	2020
Interest rate	3.31%	3.30%	2.55%
Floating Rate Notes, Due 2019
Debt Instrument [Line Items]
Maturity year	2019
Interest rate	3.13%	3.29%	2.70%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit Facility interest rate	3.21%	3.07%
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Maturity year	2018
Interest rate on notes	6.60%

Long-Term Debt - Additional Information (Detail)	3 Months Ended
Long-Term Debt - Additional Information (Detail)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Apr. 17, 2018 USD ($)
Debt Instrument [Line Items]
Maximum consolidated debt reduction for unrestricted cash and cash equivalents for debt covenant calculation	$ 200,000,000
Outstanding letters of credit	36,100,000
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
Debt instrument maturity period	Dec. 05, 2023
Senior unsecured revolving facility, maturity period	5 years
Outstanding letters of credit	$ 2,300,000	$ 2,300,000
Trade Receivable Facility
Debt Instrument [Line Items]
Credit facility commitment			$ 400,000,000
Debt instrument maturity period	Sep. 25, 2019
Trade Receivable Facility \| London Interbank Offered Rate(LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	0.725%

Financial Instruments - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) Customer	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Long-term debt, carrying values	$ 3,161,284	$ 3,120,481
Long-term debt, fair values	$ 3,130,000	$ 3,010,000
Customer Concentration Risk \| Total Revenues
Debt Instrument [Line Items]
Number of customer accounted for 10% or more of consolidated total revenues \| Customer	0
Customer Concentration Risk \| Total Revenues \| Minimum
Debt Instrument [Line Items]
Percentage of concentration risk	10.00%

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Discrete benefit from change in tax status of subsidiary from partnership to corporation	$ 13,200
Income tax (benefit) expense	$ (4,991)	$ 2,457

Pension and Postretirement Benefits - Schedule of Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,872	$ 8,148
Interest cost	9,395	8,361
Expected return on assets	(11,966)	(10,629)
Prior service cost (credit)	2	26
Actuarial loss (gain)	3,932	3,296
Net periodic benefit cost (credit)	9,235	9,202
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	15	22
Interest cost	131	125
Prior service cost (credit)	(190)	(611)
Actuarial loss (gain)	(118)	(57)
Net periodic benefit cost (credit)	$ (162)	$ (521)

Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Commitments and Contingencies [Line Items]
Guarantee of affiliate's obligations	$ 15,500,000
Due from affiliate	12,800,000
Outstanding letters of credit	$ 36,100,000
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
Revolving Facility
Commitments and Contingencies [Line Items]
Maturity date	Dec. 05, 2023
Outstanding letters of credit	$ 2,300,000	$ 2,300,000
Interest-only loan
Commitments and Contingencies [Line Items]
Due from affiliate	$ 6,000,000.0	$ 6,000,000.0
Maturity date	Dec. 31, 2022
Interest-only loan \| London Interbank Offered Rate(LIBOR)
Commitments and Contingencies [Line Items]
Basis spread on variable rate	1.75%
Revolving Line Of Credit Expires In August 2015
Commitments and Contingencies [Line Items]
Line of credit maturity period	2020-03

Business Segments - Additional Information (Detail)	3 Months Ended
Business Segments - Additional Information (Detail)	Mar. 31, 2019 Segment
Segment Reporting [Abstract]
Reportable business segments	3

Business Segments - Financial Data for Continuing Operations for Company's Reportable Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total Revenues	$ 938,955	$ 802,004
Earnings (Loss) from operations	69,221	39,081
Assets employed	10,048,407		$ 9,551,419
Products and Services
Segment Reporting Information [Line Items]
Total Revenues	878,305	753,305
Building Materials Business
Segment Reporting Information [Line Items]
Total Revenues	864,881	732,742
Earnings (Loss) from operations	72,025	43,159
Assets employed	9,572,358		9,077,562
Building Materials Business \| Products and Services
Segment Reporting Information [Line Items]
Total Revenues	809,131	688,436
Operating Segments \| Building Materials Business Mid-America Group
Segment Reporting Information [Line Items]
Total Revenues	248,813	178,781
Earnings (Loss) from operations	30,955	6,167
Assets employed	2,848,652		2,788,454
Operating Segments \| Building Materials Business Mid-America Group \| Products and Services
Segment Reporting Information [Line Items]
Total Revenues	230,308	167,890
Operating Segments \| Building Materials Business Southeast Group
Segment Reporting Information [Line Items]
Total Revenues	119,237	80,239
Earnings (Loss) from operations	21,134	2,041
Assets employed	1,443,597		1,299,469
Operating Segments \| Building Materials Business Southeast Group \| Products and Services
Segment Reporting Information [Line Items]
Total Revenues	115,312	77,563
Operating Segments \| Building Materials Business West Group
Segment Reporting Information [Line Items]
Total Revenues	496,831	473,722
Earnings (Loss) from operations	19,936	34,951
Assets employed	5,280,109		4,989,639
Operating Segments \| Building Materials Business West Group \| Products and Services
Segment Reporting Information [Line Items]
Total Revenues	463,511	442,983
Operating Segments \| Magnesia Specialties
Segment Reporting Information [Line Items]
Total Revenues	74,074	69,262
Earnings (Loss) from operations	22,642	21,237
Assets employed	170,833		156,106
Operating Segments \| Magnesia Specialties \| Products and Services
Segment Reporting Information [Line Items]
Total Revenues	69,174	64,869
Operating Segments \| Building Materials Business
Segment Reporting Information [Line Items]
Total Revenues	864,881	732,742
Corporate
Segment Reporting Information [Line Items]
Earnings (Loss) from operations	(25,446)	$ (25,315)
Assets employed	$ 305,216		$ 317,751

Revenues and Gross Profit - Total Revenues and Gross Profit by Product Line (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Product Information [Line Items]
Total revenues	$ 938,955	$ 802,004
Gross profit (loss)	142,907	110,392
Interproduct Revenues
Product Information [Line Items]
Total revenues	(58,361)	(60,665)
Corporate
Product Information [Line Items]
Gross profit (loss)	(474)	1,884
Building Materials Business
Product Information [Line Items]
Total revenues	864,881	732,742
Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	864,881	732,742
Gross profit (loss)	117,839	84,619
Building Materials Business \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	809,131	688,436
Gross profit (loss)	118,004	84,738
Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	74,074	69,262
Gross profit (loss)	25,542	23,889
Magnesia Specialties \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	69,174	64,869
Gross profit (loss)	26,607	25,063
Aggregates \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	541,473	425,016
Gross profit (loss)	97,562	53,002
Cement \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	99,017	89,183
Gross profit (loss)	13,779	23,734
Ready Mixed Concrete \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	211,156	218,537
Gross profit (loss)	14,492	15,641
Asphalt and Paving \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	15,846	16,365
Gross profit (loss)	(7,829)	(7,639)
Freight
Product Information [Line Items]
Total revenues	60,650	48,699
Freight \| Building Materials Business
Product Information [Line Items]
Total revenues	55,750	44,306
Freight \| Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	55,750	44,306
Gross profit (loss)	(165)	(119)
Freight \| Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	4,900	4,393
Gross profit (loss)	$ (1,065)	$ (1,174)

Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Lessee Lease Description [Line Items]
Option to extend lease	options to extend the leases for up to 30 years
Option to terminate lease	options to terminate the leases within one year
Operating leases primarly for equipment and land	$ 1.7
Lease expenses for operating lease		$ 122.5
Total royalties		$ 52.5
Minimum
Lessee Lease Description [Line Items]
Financing lease term	1 year
Estimated incremental percentage on interest rate	3.50%
Lease terms	2 years
Maximum
Lessee Lease Description [Line Items]
Financing lease term	54 years
Estimated incremental percentage on interest rate	5.50%
Lease terms	10 years

Leases - Summary of Components of Lease Cost (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 19,966
Finance lease cost:
Amortization of right-of-use assets	935
Interest on lease liabilities	148
Variable lease cost	4,667
Short-term lease cost	8,118
Total lease cost	$ 33,834

Leases - Summary of Balance Sheet Classifications of Operating and Finance Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Operating Leases:
Operating lease right-of-use assets	$ 498,233
Current operating lease liabilities	50,776
Noncurrent operating lease liabilities	446,128
Total operating lease liabilities	496,904
Finance Leases:
Property, plant and equipment	11,143
Accumulated depreciation	(935)
Property, plant and equipment, net	10,208
Other current liabilities	3,456	$ 3,249
Other noncurrent liabilities	7,862	7,630
Total finance lease liabilities	$ 11,318	$ 10,879

Leases - Summary of Weighted-average Remaining Lease Terms and Discount Rates (Detail)	Mar. 31, 2019
Weighted-average remaining lease term (years):
Operating leases	15 years
Finance leases	8 years 2 months 12 days
Weighted-average discount rate:
Operating leases	4.30%
Finance leases	5.10%

Leases - Summary of Future Lease Payments under Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Operating Leases
2019	$ 53,014
2020	63,870	$ 70,478
2021	52,674	60,382
2022	48,376	57,531
2023	45,912	56,511
Thereafter	429,013	318,147
Total lease payments	692,859	669,004
Less: imputed interest	(195,593)
Present value of lease payments	497,266
Less: current lease obligations	(50,776)
Total long-term lease obligations	446,490
Financing Leases
2019	2,956
2020	3,243	2,695
2021	1,951	1,735
2022	1,094	1,004
2023	779	713
Thereafter	4,176	3,893
Total lease payments	14,199	13,758
Less: imputed interest	(2,881)	(2,879)
Total finance lease liabilities	11,318	10,879
Less: current lease obligations	(3,456)	(3,249)
Other noncurrent liabilities	$ 7,862	$ 7,630

Leases - Summary of Other Leases Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 19,512
Operating cash flows used for finance leases	148
Financing cash flows used for finance leases	951
Right-of-use assets obtained in exchange for new operating lease liabilities	16,924
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 217

Leases - Summary of Future Minimum Lease and Royalty Commitments for all Noncancelable Agreements and Capital Lease Obligations (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
2019		$ 3,718
2020	$ 3,243	2,695
2021	1,951	1,735
2022	1,094	1,004
2023	779	713
Thereafter	4,176	3,893
Total lease payments	14,199	13,758
Less: imputed interest	(2,881)	(2,879)
Total finance lease liabilities	11,318	10,879
Less: current lease obligations	(3,456)	(3,249)
Other noncurrent liabilities	7,862	7,630
2019		105,955
2020	63,870	70,478
2021	52,674	60,382
2022	48,376	57,531
2023	45,912	56,511
Thereafter	429,013	318,147
Total lease payments	$ 692,859	669,004
2019		14,614
2020		11,364
2021		10,335
2022		9,545
2023		8,109
Thereafter		65,981
Total		$ 119,948

Supplemental Cash Flow Information - Schedule Of Noncash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Accrued liabilities for purchases of property, plant and equipment	$ 20,629	$ 35,639
Acquisition of assets through swap	1,114
Note receivable issued in connection with sale of property, plant and equipment	$ 1,272
Acquisition of assets through capital lease		$ 192

Supplemental Cash Flow Information -Supplemental Disclosures of Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 17,750	$ 12,458
Cash paid for (refund of) income taxes	$ 3,905	$ (7,527)

Bluegrass Acquisition - Additional Information (Detail) $ in Millions	1 Months Ended
	Apr. 30, 2018 USD ($)
Bluegrass Materials Company
Business Combinations [Line Items]
Business acquisition in cash	$ 1,620

Bluegrass Acquisition - Summary of Preliminary Estimated Fair Values of the Assets Acquired and the Liabilities Assumed (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Apr. 30, 2018
Assets:
Goodwill	$ 2,397,483	$ 2,399,118
Bluegrass Materials Company
Assets:
Cash			$ 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			242,981
Total assets			1,856,722
Liabilities:
Accounts payable and accrued expenses			17,978
Deferred income tax liabilities, net			212,386
Noncontrolling interest			9,001
Total liabilities			239,365
Total consideration			$ 1,617,357

Bluegrass Acquisition - Business Acquisition, Pro Forma Information (Details) - Bluegrass Materials Company $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares
Business Acquisition [Line Items]
Total revenues	$ 840,909
Net earnings attributable to Martin Marietta	$ 2,988
Diluted EPS \| $ / shares	$ 0.05

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	Apr. 25, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	MLM
Entity Registrant Name	MARTIN MARIETTA MATERIALS INC
Entity Central Index Key	0000916076
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		62,594,087

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 37,357	$ 44,892
Accounts receivable, net	550,607	523,276
Inventories, net	646,176	663,035
Other current assets	135,971	134,613
Total Current Assets	1,370,111	1,365,816
Property, plant and equipment	8,339,050	8,294,962
Allowances for depreciation, depletion and amortization	(3,192,368)	(3,137,733)
Net property, plant and equipment	5,146,682	5,157,229
Goodwill	2,397,483	2,399,118
Other intangibles, net	498,195	501,282
Operating lease right-of-use assets	498,233
Other noncurrent assets	137,703	127,974
Total Assets	10,048,407	9,551,419
Current Liabilities:
Accounts payable	184,844	210,808
Accrued salaries, benefits and payroll taxes	27,313	51,434
Pension and postretirement benefits	9,923	9,942
Accrued insurance and other taxes	52,895	63,543
Current maturities of long-term debt and short-term facilities	360,056	390,042
Accrued interest	31,844	17,176
Operating lease liabilities	50,776
Other current liabilities	39,986	43,805
Total Current Liabilities	757,637	786,750
Long-term debt	2,801,228	2,730,439
Pension, postretirement and postemployment benefits	138,049	134,469
Deferred income taxes, net	695,771	705,564
Noncurrent operating lease liabilities	446,128
Other noncurrent liabilities	234,098	244,785
Total Liabilities	5,072,911	4,602,007
Equity:
Common stock, par value $0.01 per share	625	624
Preferred stock, par value $0.01 per share
Additional paid-in capital	3,406,456	3,396,059
Accumulated other comprehensive loss	(140,324)	(143,579)
Retained earnings	1,705,717	1,693,259
Total Shareholders' Equity	4,972,474	4,946,363
Noncontrolling interests	3,022	3,049
Total Equity	4,975,496	4,949,412
Total Liabilities and Equity	$ 10,048,407	$ 9,551,419

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Preferred stock, par value	$ 0.01	$ 0.01

Consolidated Statements of Earnings and Comprehensive Earnings (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Total Revenues	$ 938,955	$ 802,004
Total Cost of Revenues	796,048	691,612
Gross Profit	142,907	110,392
Selling, general & administrative expenses	78,292	70,121
Acquisition-related expenses, net	144	711
Other operating (income) expenses, net	(4,750)	479
Earnings from Operations	69,221	39,081
Interest expense	32,948	35,087
Other nonoperating income, net	(1,562)	(8,503)
Earnings before income tax expense	37,835	12,497
Income tax (benefit) expense	(4,991)	2,457
Consolidated net earnings	42,826	10,040
Less: Net (loss) earnings attributable to noncontrolling interests	(27)	17
Net Earnings Attributable to Martin Marietta Materials, Inc.	42,853	10,023
Consolidated Comprehensive Earnings:
Earnings attributable to Martin Marietta Materials, Inc.	46,108	11,642
(Loss) Earnings attributable to noncontrolling interests	(27)	17
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 46,081	$ 11,659
Net Earnings Attributable to Martin Marietta Materials, Inc. Per Common Share:
Basic attributable to common shareholders	$ 0.68	$ 0.16
Diluted attributable to common shareholders	$ 0.68	$ 0.16
Weighted-Average Common Shares Outstanding:
Basic	62,584	62,957
Diluted	62,777	63,222
Products and Services
Total Revenues	$ 878,305	$ 753,305
Total Cost of Revenues	734,168	641,620
Freight
Total Revenues	60,650	48,699
Total Cost of Revenues	$ 61,880	$ 49,992

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities:
Consolidated net earnings	$ 42,826	$ 10,040
Adjustments to reconcile consolidated net earnings to net cash provided by operating activities:
Depreciation, depletion and amortization	89,211	76,821
Stock-based compensation expense	13,552	9,760
Gain on divestitures and sales of assets	(2,413)	(951)
Deferred income taxes	4,781	2,029
Other items, net	495	(2,269)
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable, net	(26,059)	20,951
Inventories, net	16,416	(8,873)
Accounts payable	20,393	7,925
Other assets and liabilities, net	(41,338)	(10,421)
Net Cash Provided by Operating Activities	117,864	105,012
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(130,056)	(96,259)
Proceeds from divestitures and sales of assets	2,927	2,528
Payment of railcar construction advances		(8,430)
Reimbursement of railcar construction advances		8,430
Investments in life insurance contracts, net	193	99
Other investing activities, net	(600)
Net Cash Used for Investing Activities	(127,536)	(93,632)
Cash Flows from Financing Activities:
Borrowings of debt	125,000
Repayments of debt	(85,000)	(13)
Payments on finance leases	(951)
Payments on capital lease		(829)
Debt issuance costs		(3,194)
Contributions by owners of noncontrolling interest		129
Dividends paid	(30,395)	(27,885)
Proceeds from exercise of stock options	611	2,801
Shares withheld for employees' income tax obligations	(7,128)	(6,380)
Net Cash Provided by (Used for) Financing Activities	2,137	(35,371)
Net Decrease in Cash and Cash Equivalents	(7,535)	(23,991)
Cash and Cash Equivalents, beginning of period	44,892	1,446,364
Cash and Cash Equivalents, end of period	$ 37,357	$ 1,422,373

Consolidated Statements of Total Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Total Shareholders' Equity	Noncontrolling Interests
Beginning Balance at Dec. 31, 2017	$ 4,682,477	$ 628	$ 3,368,007	$ (129,104)	$ 1,440,069	$ 4,679,600	$ 2,877
Beginning Balance (in shares) at Dec. 31, 2017		62,873
Consolidated net earnings	10,040				10,023	10,023	17
Other comprehensive earnings, net of tax	1,619			1,619		1,619
Dividends declared ($0.44 per share)	(27,885)				(27,885)	(27,885)
Issuances of common stock for stock award plans	9,893		9,893			9,893
Issuances of common stock for stock award plans (in shares)		75
Shares withheld for employees' income tax obligations	(6,380)		(6,380)			(6,380)
Stock-based compensation expense	9,760		9,760			9,760
Contributions from owners of noncontrolling interest	306						306
Ending Balance at Mar. 31, 2018	4,679,830	$ 628	3,381,280	(127,485)	1,422,207	4,676,630	3,200
Ending Balance (in shares) at Mar. 31, 2018		62,948
Beginning Balance at Dec. 31, 2018	4,949,412	$ 624	3,396,059	(143,579)	1,693,259	4,946,363	3,049
Beginning Balance (in shares) at Dec. 31, 2018		62,515
Consolidated net earnings	42,826				42,853	42,853	(27)
Other comprehensive earnings, net of tax	3,255			3,255		3,255
Dividends declared ($0.44 per share)	(30,395)				(30,395)	(30,395)
Issuances of common stock for stock award plans	3,974	$ 1	3,973			3,974
Issuances of common stock for stock award plans (in shares)		78
Shares withheld for employees' income tax obligations	(7,128)		(7,128)			(7,128)
Stock-based compensation expense	13,552		13,552			13,552
Ending Balance at Mar. 31, 2019	$ 4,975,496	$ 625	$ 3,406,456	$ (140,324)	$ 1,705,717	$ 4,972,474	$ 3,022
Ending Balance (in shares) at Mar. 31, 2019		62,593

Consolidated Statements of Total Equity (Parenthetical) (Unaudited) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Stockholders Equity [Abstract]
Dividends declared	$ 0.48	$ 0.44

Significant Accounting Policies

3 Months Ended

Mar. 31, 2019

Significant Accounting Policies

1.	Significant Accounting Policies

Organization

The Company’s Building Materials business includes three reportable segments: the Mid-America Group, the Southeast Group and the West Group.

BUILDING MATERIALS BUSINESS
Reportable Segments	Mid-America Group	Southeast Group	West Group
Operating Locations	Indiana, Iowa, northern Kansas, Kentucky, Maryland, Minnesota, Missouri, eastern Nebraska, North Carolina, Ohio, Pennsylvania, South Carolina, Virginia, Washington and West Virginia	Alabama, Florida, Georgia, Tennessee, Nova Scotia and the Bahamas	Arkansas, Colorado, southern Kansas, Louisiana, western Nebraska, Nevada, Oklahoma, Texas, Utah and Wyoming

Product Lines	Aggregates	Aggregates	Aggregates, Cement, Ready Mixed Concrete, Asphalt and Paving

Basis of Presentation

New Accounting Pronouncement

Leases

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2019		2018
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Other comprehensive earnings, net of tax		3,255		1,619
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	46,108	$	11,642

Changes in accumulated other comprehensive earnings, net of tax, are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Accumulated Other Comprehensive Loss

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)
Other comprehensive earnings before reclassifications, net of tax		—			497			—			497
Amounts reclassified from accumulated other comprehensive loss, net of tax		2,758			—			—			2,758
Other comprehensive earnings, net of tax		2,758			497			—			3,255
Balance at end of period	$	(138,747	)	$	(1,577	)	$	—		$	(140,324	)

	Three Months Ended March 31, 2018
Balance at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		—			(587	)		—			(587	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		1,996			—			210			2,206
Other comprehensive earnings (loss), net of tax		1,996			(587	)		210			1,619
Balance at end of period	$	(126,806	)	$	(609	)	$	(70	)	$	(127,485	)

Changes in net noncurrent deferred tax assets recorded in accumulated other comprehensive loss are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Net Noncurrent Deferred Tax Assets

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84,207		$	—		$	84,207
Tax effect of other comprehensive earnings		(868	)		—			(868	)
Balance at end of period	$	83,339		$	—		$	83,339

	Three Months Ended March 31, 2018
Balance at beginning of period	$	79,938		$	178		$	80,116
Tax effect of other comprehensive earnings		(658	)		(137	)		(795	)
Balance at end of period	$	79,280		$	41		$	79,321

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2019			2018			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	(188	)	$	(585	)
Actuarial loss		3,814			3,239
		3,626			2,654		Other nonoperating income, net
Tax benefit		(868	)		(658	)	Income tax (benefit) expense
	$	2,758		$	1,996

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	—		$	347		Interest expense
Tax benefit		—			(137	)	Income tax (benefit) expense
	$	—		$	210

Earnings per Common Share

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

	Three Months Ended
	March 31,
	2019		2018
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Less: Distributed and undistributed earnings attributable to unvested awards		86		63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	42,767	$	9,960

Basic weighted-average common shares outstanding		62,584		62,957
Effect of dilutive employee and director awards		193		265
Diluted weighted-average common shares outstanding		62,777		63,222

Revenue Recognition

3 Months Ended

Mar. 31, 2019

Revenue Recognition

2.	Revenue Recognition

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

	Three Months Ended
	March 31, 2019
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	230,308	$	18,505	$	248,813
Southeast Group		115,312		3,925		119,237
West Group		463,511		33,320		496,831
Total Building Materials Business		809,131		55,750		864,881
Magnesia Specialties		69,174		4,900		74,074
Total	$	878,305	$	60,650	$	938,955

	Three Months Ended
	March 31, 2018
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	167,890	$	10,891	$	178,781
Southeast Group		77,563		2,676		80,239
West Group		442,983		30,739		473,722
Total Building Materials Business		688,436		44,306		732,742
Magnesia Specialties		64,869		4,393		69,262
Total	$	753,305	$	48,699	$	802,004

Service revenues, which include paving operations located in Colorado, were $9.9 million and $11.1 million for the three months ended March 31, 2019 and 2018, respectively.

(Dollars in Thousands)	March 31, 2019		December 31, 2018
Costs in excess of billings	$	2,238	$	1,975
Billings in excess of costs	$	5,814	$	6,743

Revenues recognized from the beginning balance of contract liabilities for the three months ended March 31, 2019 and 2018 were $3.8 million and $4.2 million, respectively.

Inventories, Net

3 Months Ended

Mar. 31, 2019

Inventories, Net

3.	Inventories, Net

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
Finished products	$	605,785		$	615,719
Products in process and raw materials		63,114			66,920
Supplies and expendable parts		136,792			139,566
		805,691			822,205
Less: Allowances		(159,515	)		(159,170	)
Total	$	646,176		$	663,035

Long-Term Debt

3 Months Ended

Mar. 31, 2019

Financial Instruments Disclosure [Abstract]

4.	Long-Term Debt

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
4.25% Senior Notes, due 2024	$	396,547		$	396,398
7% Debentures, due 2025		124,296			124,272
3.450% Senior Notes, due 2027		297,019			296,939
3.500% Senior Notes, due 2027		494,888			494,765
6.25% Senior Notes, due 2037		228,110			228,094
4.250% Senior Notes, due 2047		591,583			591,541
Floating Rate Notes, due 2019, interest rate of 3.13%, 3.29% and 2.70% at March 31, 2019 and December 31, 2018, respectively		299,446			299,260
Floating Rate Notes, due 2020, interest rate of 3.31%, 3.30% and 2.55% at March 31, 2019 and December 31, 2018, respectively		299,139			298,956
6.60% Senior Notes, due 2018		—			—
Revolving Facility, due 2023, interest rate of 3.59% at March 31, 2019		70,000			—
Trade Receivable Facility, interest rate of 3.21% and 3.07% at March 31, 2019 and December 31, 2018, respectively		360,000			390,000
Other notes		256			256
Total debt		3,161,284			3,120,481
Less: Current maturities of long-term debt and short-term facilities		(360,056	)		(390,042	)
Long-term debt	$	2,801,228		$	2,730,439

Financial Instruments

3 Months Ended

Mar. 31, 2019

Financial Instruments

5.	Financial Instruments

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

Notes receivable are not publicly traded. Management estimates that the fair value of notes receivable approximates the carrying amount due to the short-term nature of the receivables.

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.

Income Taxes

3 Months Ended

Mar. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

6.	Income Taxes

Pension and Postretirement Benefits

3 Months Ended

Mar. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Pension and Postretirement Benefits

7.	Pension and Postretirement Benefits

The estimated components of the recorded net periodic benefit cost (credit) for pension and postretirement benefits are as follows:

	Pension						Postretirement Benefits
	Three Months Ended March 31,
	2019			2018			2019			2018
	(Dollars in Thousands)
Service cost	$	7,872		$	8,148		$	15		$	22
Interest cost		9,395			8,361			131			125
Expected return on assets		(11,966	)		(10,629	)		—			—
Amortization of:
Prior service cost (credit)		2			26			(190	)		(611	)
Actuarial loss (gain)		3,932			3,296			(118	)		(57	)
Net periodic benefit cost (credit)	$	9,235		$	9,202		$	(162	)	$	(521	)

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

8.	Commitments and Contingencies

Legal and Administrative Proceedings

Borrowing Arrangements with Affiliate

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.

Letters of Credit

Employees

Business Segments

3 Months Ended

Mar. 31, 2019

Business Segments

9.	Business Segments

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Mid-America Group	$	248,813		$	178,781
Southeast Group		119,237			80,239
West Group		496,831			473,722
Total Building Materials Business		864,881			732,742
Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Products and services revenues:
Mid-America Group	$	230,308		$	167,890
Southeast Group		115,312			77,563
West Group		463,511			442,983
Total Building Materials Business		809,131			688,436
Magnesia Specialties		69,174			64,869
Total	$	878,305		$	753,305

Earnings (Loss) from operations:
Mid-America Group	$	30,955		$	6,167
Southeast Group		21,134			2,041
West Group		19,936			34,951
Total Building Materials Business		72,025			43,159
Magnesia Specialties		22,642			21,237
Corporate		(25,446	)		(25,315	)
Total	$	69,221		$	39,081

	March 31, 2019		December 31, 2018
Assets employed:	(Dollars in thousands)
Mid-America Group	$	2,848,652	$	2,788,454
Southeast Group		1,443,597		1,299,469
West Group		5,280,109		4,989,639
Total Building Materials Business		9,572,358		9,077,562
Magnesia Specialties		170,833		156,106
Corporate		305,216		317,751
Total	$	10,048,407	$	9,551,419

Revenues and Gross Profit

3 Months Ended

Mar. 31, 2019

Revenues and Gross Profit

10.	Revenues and Gross Profit

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Building Materials Business:
Products and services:
Aggregates	$	541,473		$	425,016
Cement		99,017			89,183
Ready mixed concrete		211,156			218,537
Asphalt and paving services		15,846			16,365
Less: interproduct revenues		(58,361	)		(60,665	)
Products and services		809,131			688,436
Freight		55,750			44,306
Total Building Materials Business		864,881			732,742
Magnesia Specialties:
Products and services		69,174			64,869
Freight		4,900			4,393
Total Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Gross profit (loss):
Building Materials Business:
Products and services:
Aggregates	$	97,562		$	53,002
Cement		13,779			23,734
Ready mixed concrete		14,492			15,641
Asphalt and paving services		(7,829	)		(7,639	)
Products and services		118,004			84,738
Freight		(165	)		(119	)
Total Building Materials Business		117,839			84,619
Magnesia Specialties:
Products and services		26,607			25,063
Freight		(1,065	)		(1,174	)
Total Magnesia Specialties		25,542			23,889
Corporate		(474	)		1,884
Total	$	142,907		$	110,392

Leases

3 Months Ended

Mar. 31, 2019

Leases

11.

Leases

The components of lease cost are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating lease cost	$	19,966
Finance lease cost:
Amortization of right-of-use assets		935
Interest on lease liabilities		148
Variable lease cost		4,667
Short-term lease cost		8,118
Total lease cost	$	33,834

The balance sheet classifications of operating and finance leases are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating Leases:
Operating lease right-of-use assets	$	498,233

Current operating lease liabilities	$	50,776
Noncurrent operating lease liabilities		446,128
Total operating lease liabilities	$	496,904

Finance Leases:
Property, plant and equipment	$	11,143
Accumulated depreciation		(935	)
Property, plant and equipment, net	$	10,208

Other current liabilities	$	3,456
Other noncurrent liabilities		7,862
Total finance lease liabilities	$	11,318

The estimated incremental borrowing rate range used was 3.5% to 5.5%. Weighted-average remaining lease terms and discount rates are as follows:

	March 31, 2019
Weighted-average remaining lease term (years):
Operating leases		15.0
Finance leases		8.2

Weighted-average discount rate:
Operating leases		4.3	%
Finance leases		5.1	%

Future lease payments under leases as of March 31, 2019 are as follows:

	Operating			Finance
	Leases			Leases
	(Dollars in Thousands)
2019	$	53,014		$	2,956
2020		63,870			3,243
2021		52,674			1,951
2022		48,376			1,094
2023		45,912			779
Thereafter		429,013			4,176
Total lease payments		692,859			14,199
Less: imputed interest		(195,593	)		(2,881	)
Present value of lease payments		497,266			11,318
Less: current lease obligations		(50,776	)		(3,456	)
Total long-term lease obligations	$	446,490		$	7,862

Other lease information is as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$	19,512
Operating cash flows used for finance leases	$	148
Financing cash flows used for finance leases	$	951
Right-of-use assets obtained in exchange for new operating lease liabilities	$	16,924
Right-of-use assets obtained in exchange for new finance lease liabilities	$	217

Lease disclosures for the full year December 31, 2018, as reported:

	Capital Leases			Operating Leases		Royalty Commitments
	(Dollars in Thousands)
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

Supplemental Cash Flow Information

3 Months Ended

Mar. 31, 2019

Supplemental Cash Flow Information

12.	Supplemental Cash Flow Information

Noncash investing and financing activities are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	20,629	$	35,639
Acquisition of assets through swap	$	1,114	$	—
Note receivable issued in connection with sale of property, plant and equipment	$	1,272	$	—
Acquisition of assets through capital lease	$	—	$	192

Supplemental disclosures of cash flow information are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Cash paid for interest	$	17,750	$	12,458
Cash paid for (refund of) income taxes	$	3,905	$	(7,527	)

Bluegrass Acquisition

3 Months Ended

Mar. 31, 2019

Bluegrass Acquisition

13.	Bluegrass Acquisition

Assets:
Cash	$	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		242,981
Total assets		1,856,722

Liabilities:
Accounts payable and accrued expenses		17,978
Deferred income tax liabilities, net		212,386
Noncontrolling interest		9,001
Total liabilities		239,365

Total consideration	$	1,617,357

The following presents pro forma results for the quarter ended March 31, 2018:

(Dollars in Thousands, except per share data)
Total revenues	$	840,909
Net earnings attributable to Martin Marietta	$	2,988
Diluted EPS	$	0.05

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2019

New Accounting Pronouncement

Organization

The Company’s Building Materials business includes three reportable segments: the Mid-America Group, the Southeast Group and the West Group.

BUILDING MATERIALS BUSINESS
Reportable Segments	Mid-America Group	Southeast Group	West Group
Operating Locations	Indiana, Iowa, northern Kansas, Kentucky, Maryland, Minnesota, Missouri, eastern Nebraska, North Carolina, Ohio, Pennsylvania, South Carolina, Virginia, Washington and West Virginia	Alabama, Florida, Georgia, Tennessee, Nova Scotia and the Bahamas	Arkansas, Colorado, southern Kansas, Louisiana, western Nebraska, Nevada, Oklahoma, Texas, Utah and Wyoming

Product Lines	Aggregates	Aggregates	Aggregates, Cement, Ready Mixed Concrete, Asphalt and Paving

Basis of Presentation

Leases

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2019		2018
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Other comprehensive earnings, net of tax		3,255		1,619
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	46,108	$	11,642

Changes in accumulated other comprehensive earnings, net of tax, are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Accumulated Other Comprehensive Loss

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)
Other comprehensive earnings before reclassifications, net of tax		—			497			—			497
Amounts reclassified from accumulated other comprehensive loss, net of tax		2,758			—			—			2,758
Other comprehensive earnings, net of tax		2,758			497			—			3,255
Balance at end of period	$	(138,747	)	$	(1,577	)	$	—		$	(140,324	)

	Three Months Ended March 31, 2018
Balance at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		—			(587	)		—			(587	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		1,996			—			210			2,206
Other comprehensive earnings (loss), net of tax		1,996			(587	)		210			1,619
Balance at end of period	$	(126,806	)	$	(609	)	$	(70	)	$	(127,485	)

Changes in net noncurrent deferred tax assets recorded in accumulated other comprehensive loss are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Net Noncurrent Deferred Tax Assets

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84,207		$	—		$	84,207
Tax effect of other comprehensive earnings		(868	)		—			(868	)
Balance at end of period	$	83,339		$	—		$	83,339

	Three Months Ended March 31, 2018
Balance at beginning of period	$	79,938		$	178		$	80,116
Tax effect of other comprehensive earnings		(658	)		(137	)		(795	)
Balance at end of period	$	79,280		$	41		$	79,321

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2019			2018			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	(188	)	$	(585	)
Actuarial loss		3,814			3,239
		3,626			2,654		Other nonoperating income, net
Tax benefit		(868	)		(658	)	Income tax (benefit) expense
	$	2,758		$	1,996

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	—		$	347		Interest expense
Tax benefit		—			(137	)	Income tax (benefit) expense
	$	—		$	210

Earnings per Common Share

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

	Three Months Ended
	March 31,
	2019		2018
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Less: Distributed and undistributed earnings attributable to unvested awards		86		63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	42,767	$	9,960

Basic weighted-average common shares outstanding		62,584		62,957
Effect of dilutive employee and director awards		193		265
Diluted weighted-average common shares outstanding		62,777		63,222

Policy Elections

Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2019

Changes in Accumulated Other Comprehensive Earnings Net of Tax

Changes in accumulated other comprehensive earnings, net of tax, are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Accumulated Other Comprehensive Loss

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)
Other comprehensive earnings before reclassifications, net of tax		—			497			—			497
Amounts reclassified from accumulated other comprehensive loss, net of tax		2,758			—			—			2,758
Other comprehensive earnings, net of tax		2,758			497			—			3,255
Balance at end of period	$	(138,747	)	$	(1,577	)	$	—		$	(140,324	)

	Three Months Ended March 31, 2018
Balance at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before reclassifications, net of tax		—			(587	)		—			(587	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		1,996			—			210			2,206
Other comprehensive earnings (loss), net of tax		1,996			(587	)		210			1,619
Balance at end of period	$	(126,806	)	$	(609	)	$	(70	)	$	(127,485	)

Noncurrent Deferred Tax Assets Recorded In Accumulated Other Comprehensive Loss

Changes in net noncurrent deferred tax assets recorded in accumulated other comprehensive loss are as follows:

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Net Noncurrent Deferred Tax Assets

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84,207		$	—		$	84,207
Tax effect of other comprehensive earnings		(868	)		—			(868	)
Balance at end of period	$	83,339		$	—		$	83,339

	Three Months Ended March 31, 2018
Balance at beginning of period	$	79,938		$	178		$	80,116
Tax effect of other comprehensive earnings		(658	)		(137	)		(795	)
Balance at end of period	$	79,280		$	41		$	79,321

Reclassification Out of Accumulated Other Comprehensive Loss

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2019			2018			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	(188	)	$	(585	)
Actuarial loss		3,814			3,239
		3,626			2,654		Other nonoperating income, net
Tax benefit		(868	)		(658	)	Income tax (benefit) expense
	$	2,758		$	1,996

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	—		$	347		Interest expense
Tax benefit		—			(137	)	Income tax (benefit) expense
	$	—		$	210

Basic and Diluted Earnings Per Common Share

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

	Three Months Ended
	March 31,
	2019		2018
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Less: Distributed and undistributed earnings attributable to unvested awards		86		63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	42,767	$	9,960

Basic weighted-average common shares outstanding		62,584		62,957
Effect of dilutive employee and director awards		193		265
Diluted weighted-average common shares outstanding		62,777		63,222

Parent

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2019		2018
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	42,853	$	10,023
Other comprehensive earnings, net of tax		3,255		1,619
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	46,108	$	11,642

Noncontrolling Interests

Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2019

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:

	Three Months Ended
	March 31, 2019
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	230,308	$	18,505	$	248,813
Southeast Group		115,312		3,925		119,237
West Group		463,511		33,320		496,831
Total Building Materials Business		809,131		55,750		864,881
Magnesia Specialties		69,174		4,900		74,074
Total	$	878,305	$	60,650	$	938,955

	Three Months Ended
	March 31, 2018
(Dollars in Thousands)	Products and Services		Freight		Total
Mid-America Group	$	167,890	$	10,891	$	178,781
Southeast Group		77,563		2,676		80,239
West Group		442,983		30,739		473,722
Total Building Materials Business		688,436		44,306		732,742
Magnesia Specialties		64,869		4,393		69,262
Total	$	753,305	$	48,699	$	802,004

Summary of Information About the Company's Contract Balances

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

(Dollars in Thousands)	March 31, 2019		December 31, 2018
Costs in excess of billings	$	2,238	$	1,975
Billings in excess of costs	$	5,814	$	6,743

Inventories, Net (Tables)

3 Months Ended

Mar. 31, 2019

Schedule of Inventories Net

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
Finished products	$	605,785		$	615,719
Products in process and raw materials		63,114			66,920
Supplies and expendable parts		136,792			139,566
		805,691			822,205
Less: Allowances		(159,515	)		(159,170	)
Total	$	646,176		$	663,035

Long-Term Debt (Tables)

3 Months Ended

Mar. 31, 2019

	March 31,			December 31,
	2019			2018
	(Dollars in Thousands)
4.25% Senior Notes, due 2024	$	396,547		$	396,398
7% Debentures, due 2025		124,296			124,272
3.450% Senior Notes, due 2027		297,019			296,939
3.500% Senior Notes, due 2027		494,888			494,765
6.25% Senior Notes, due 2037		228,110			228,094
4.250% Senior Notes, due 2047		591,583			591,541
Floating Rate Notes, due 2019, interest rate of 3.13%, 3.29% and 2.70% at March 31, 2019 and December 31, 2018, respectively		299,446			299,260
Floating Rate Notes, due 2020, interest rate of 3.31%, 3.30% and 2.55% at March 31, 2019 and December 31, 2018, respectively		299,139			298,956
6.60% Senior Notes, due 2018		—			—
Revolving Facility, due 2023, interest rate of 3.59% at March 31, 2019		70,000			—
Trade Receivable Facility, interest rate of 3.21% and 3.07% at March 31, 2019 and December 31, 2018, respectively		360,000			390,000
Other notes		256			256
Total debt		3,161,284			3,120,481
Less: Current maturities of long-term debt and short-term facilities		(360,056	)		(390,042	)
Long-term debt	$	2,801,228		$	2,730,439

Compensation And Retirement Disclosure [Abstract]

+ References

+ Details

Pension and Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2019

Schedule of Components of Net Periodic Benefit Cost (Credit)

The estimated components of the recorded net periodic benefit cost (credit) for pension and postretirement benefits are as follows:

	Pension						Postretirement Benefits
	Three Months Ended March 31,
	2019			2018			2019			2018
	(Dollars in Thousands)
Service cost	$	7,872		$	8,148		$	15		$	22
Interest cost		9,395			8,361			131			125
Expected return on assets		(11,966	)		(10,629	)		—			—
Amortization of:
Prior service cost (credit)		2			26			(190	)		(611	)
Actuarial loss (gain)		3,932			3,296			(118	)		(57	)
Net periodic benefit cost (credit)	$	9,235		$	9,202		$	(162	)	$	(521	)

Business Segments (Tables)

3 Months Ended

Mar. 31, 2019

Financial Data for Continuing Operation for Company's Reportable Business Segments

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Mid-America Group	$	248,813		$	178,781
Southeast Group		119,237			80,239
West Group		496,831			473,722
Total Building Materials Business		864,881			732,742
Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Products and services revenues:
Mid-America Group	$	230,308		$	167,890
Southeast Group		115,312			77,563
West Group		463,511			442,983
Total Building Materials Business		809,131			688,436
Magnesia Specialties		69,174			64,869
Total	$	878,305		$	753,305

Earnings (Loss) from operations:
Mid-America Group	$	30,955		$	6,167
Southeast Group		21,134			2,041
West Group		19,936			34,951
Total Building Materials Business		72,025			43,159
Magnesia Specialties		22,642			21,237
Corporate		(25,446	)		(25,315	)
Total	$	69,221		$	39,081

	March 31, 2019		December 31, 2018
Assets employed:	(Dollars in thousands)
Mid-America Group	$	2,848,652	$	2,788,454
Southeast Group		1,443,597		1,299,469
West Group		5,280,109		4,989,639
Total Building Materials Business		9,572,358		9,077,562
Magnesia Specialties		170,833		156,106
Corporate		305,216		317,751
Total	$	10,048,407	$	9,551,419

Supplemental Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2019

Schedule Of Other Significant Noncash Transactions

Noncash investing and financing activities are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	20,629	$	35,639
Acquisition of assets through swap	$	1,114	$	—
Note receivable issued in connection with sale of property, plant and equipment	$	1,272	$	—
Acquisition of assets through capital lease	$	—	$	192

Supplemental Disclosures of Cash Flow Information

Supplemental disclosures of cash flow information are as follows:

	March 31,
	2019		2018
	(Dollars in Thousands)
Cash paid for interest	$	17,750	$	12,458
Cash paid for (refund of) income taxes	$	3,905	$	(7,527	)

Revenues and Gross Profit (Tables)

3 Months Ended

Mar. 31, 2019

Total Revenues and Gross Profit by Product Line

The following table, which is reconciled to consolidated amounts, provides total revenues and gross profit by product line.

	Three Months Ended
	March 31,
	2019			2018
	(Dollars in Thousands)
Total revenues:
Building Materials Business:
Products and services:
Aggregates	$	541,473		$	425,016
Cement		99,017			89,183
Ready mixed concrete		211,156			218,537
Asphalt and paving services		15,846			16,365
Less: interproduct revenues		(58,361	)		(60,665	)
Products and services		809,131			688,436
Freight		55,750			44,306
Total Building Materials Business		864,881			732,742
Magnesia Specialties:
Products and services		69,174			64,869
Freight		4,900			4,393
Total Magnesia Specialties		74,074			69,262
Total	$	938,955		$	802,004

Gross profit (loss):
Building Materials Business:
Products and services:
Aggregates	$	97,562		$	53,002
Cement		13,779			23,734
Ready mixed concrete		14,492			15,641
Asphalt and paving services		(7,829	)		(7,639	)
Products and services		118,004			84,738
Freight		(165	)		(119	)
Total Building Materials Business		117,839			84,619
Magnesia Specialties:
Products and services		26,607			25,063
Freight		(1,065	)		(1,174	)
Total Magnesia Specialties		25,542			23,889
Corporate		(474	)		1,884
Total	$	142,907		$	110,392

Leases (Tables)

3 Months Ended

Mar. 31, 2019

Summary of Components of Lease Cost

The components of lease cost are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating lease cost	$	19,966
Finance lease cost:
Amortization of right-of-use assets		935
Interest on lease liabilities		148
Variable lease cost		4,667
Short-term lease cost		8,118
Total lease cost	$	33,834

Summary of Balance Sheet Classifications of Operating and Finance Leases

The balance sheet classifications of operating and finance leases are as follows:

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Operating Leases:
Operating lease right-of-use assets	$	498,233

Current operating lease liabilities	$	50,776
Noncurrent operating lease liabilities		446,128
Total operating lease liabilities	$	496,904

Finance Leases:
Property, plant and equipment	$	11,143
Accumulated depreciation		(935	)
Property, plant and equipment, net	$	10,208

Other current liabilities	$	3,456
Other noncurrent liabilities		7,862
Total finance lease liabilities	$	11,318

Summary of Weighted-average Remaining Lease Terms and Discount Rates

Weighted-average remaining lease terms and discount rates are as follows:

	March 31, 2019
Weighted-average remaining lease term (years):
Operating leases		15.0
Finance leases		8.2

Weighted-average discount rate:
Operating leases		4.3	%
Finance leases		5.1	%

Summary of Future Lease Payments under Noncancellable Leases

Future lease payments under leases as of March 31, 2019 are as follows:

	Operating			Finance
	Leases			Leases
	(Dollars in Thousands)
2019	$	53,014		$	2,956
2020		63,870			3,243
2021		52,674			1,951
2022		48,376			1,094
2023		45,912			779
Thereafter		429,013			4,176
Total lease payments		692,859			14,199
Less: imputed interest		(195,593	)		(2,881	)
Present value of lease payments		497,266			11,318
Less: current lease obligations		(50,776	)		(3,456	)
Total long-term lease obligations	$	446,490		$	7,862

Summary of Other Leases Information

	Three Months Ended
	March 31, 2019
	(Dollars in Thousands)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$	19,512
Operating cash flows used for finance leases	$	148
Financing cash flows used for finance leases	$	951
Right-of-use assets obtained in exchange for new operating lease liabilities	$	16,924
Right-of-use assets obtained in exchange for new finance lease liabilities	$	217

Summary of Future Minimum Lease and Royalty Commitments for all Noncancelable Agreements and Capital Lease Obligations

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

	Capital Leases			Operating Leases		Royalty Commitments
	(Dollars in Thousands)
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

Bluegrass Acquisition (Tables)

3 Months Ended

Mar. 31, 2019

Summary of 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 (dollars in thousands):

Assets:
Cash	$	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		242,981
Total assets		1,856,722

Liabilities:
Accounts payable and accrued expenses		17,978
Deferred income tax liabilities, net		212,386
Noncontrolling interest		9,001
Total liabilities		239,365

Total consideration	$	1,617,357

Business Acquisition, Pro Forma Information

The following presents pro forma results for the quarter ended March 31, 2018:

(Dollars in Thousands, except per share data)
Total revenues	$	840,909
Net earnings attributable to Martin Marietta	$	2,988
Diluted EPS	$	0.05

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019 USD ($) Facility State Segment	Mar. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Significant Accounting Policies [Line Items]
Number of states with aggregates business sales by destination \| State	31
Number of reportable segments \| Segment	3
Operating lease, right of use asset	$ 498,233,000
Operating lease, liability	496,904,000
Finance leases, liability	11,318,000			$ 10,879,000
Other comprehensive earnings attributable to noncontrolling interests	$ 0	$ 0
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease, right of use asset			$ 502,500,000
Operating lease, liability			501,600,000
Finance leases, right of use asset			10,900,000
Finance leases, liability			$ 12,100,000
Minimum
Significant Accounting Policies [Line Items]
Number of quarries and yards \| Facility	300

Significant Accounting Policies - Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 42,853	$ 10,023
Other comprehensive earnings, net of tax	3,255	1,619
Earnings attributable to Martin Marietta Materials, Inc.	$ 46,108	$ 11,642

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

Significant Accounting Policies - Changes in Accumulated Other Comprehensive Earnings Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 4,949,412	$ 4,682,477
Other comprehensive earnings (loss) before reclassifications, net of tax	497	(587)
Amounts reclassified from accumulated other comprehensive loss, net of tax	2,758	2,206
Other comprehensive earnings (loss), net of tax	3,255	1,619
Ending Balance	4,975,496	4,679,830
Pension and Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(141,505)	(128,802)
Amounts reclassified from accumulated other comprehensive loss, net of tax	2,758	1,996
Other comprehensive earnings (loss), net of tax	2,758	1,996
Ending Balance	(138,747)	(126,806)
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,074)	(22)
Other comprehensive earnings (loss) before reclassifications, net of tax	497	(587)
Other comprehensive earnings (loss), net of tax	497	(587)
Ending Balance	(1,577)	(609)
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(280)
Amounts reclassified from accumulated other comprehensive loss, net of tax		210
Other comprehensive earnings (loss), net of tax		210
Ending Balance		(70)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(143,579)	(129,104)
Ending Balance	$ (140,324)	$ (127,485)

Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 84,207	$ 79,938
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans	(868)	(658)
Balance at end of period, Pension and Postretirement Benefit Plans	83,339	79,280
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap		178
Tax effect of other comprehensive earnings, Unamortized Value of Terminated Forward Starting Interest Rate Swap		(137)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap		41
Balance at beginning of period, Net Noncurrent Deferred Tax Assets	84,207	80,116
Tax effect of other comprehensive earnings, Net Noncurrent Deferred Tax Assets	(868)	(795)
Balance at end of period, Net Noncurrent Deferred Tax Assets	$ 83,339	$ 79,321

Significant Accounting Policies - Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Additional interest expense	$ 32,948	$ 35,087
Tax benefit	(4,991)	2,457
Earnings from Continuing Operations	2,758	2,206
Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	2,758	1,996
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations		210
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit	(188)	(585)
Actuarial loss	3,814	3,239
Tax benefit	(868)	(658)
Earnings from Continuing Operations	2,758	1,996
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	$ 3,626	2,654
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		347
Tax benefit		(137)
Earnings from Continuing Operations		$ 210

Significant Accounting Policies - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 42,853	$ 10,023
Less: Distributed and undistributed earnings attributable to unvested awards	86	63
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 42,767	$ 9,960
Basic weighted-average common shares outstanding	62,584	62,957
Effect of dilutive employee and director awards	193	265
Diluted weighted-average common shares outstanding	62,777	63,222

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