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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2017	Oct. 25, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
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 Common Stock, Shares Outstanding		62,859,551

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Current Assets:
Cash and cash equivalents	$ 35,219	$ 50,038	$ 60,684
Accounts receivable, net	582,532	457,910	566,425
Inventories, net	576,429	521,624	508,199
Other current assets	83,809	56,813	56,217
Total Current Assets	1,277,989	1,086,385	1,191,525
Property, plant and equipment	6,375,813	6,115,530	6,013,084
Allowances for depreciation, depletion and amortization	(2,854,236)	(2,692,135)	(2,633,471)
Net property, plant and equipment	3,521,577	3,423,395	3,379,613
Goodwill	2,160,060	2,159,337	2,160,605
Operating permits, net	440,846	442,202	444,123
Other intangibles, net	63,740	69,110	70,927
Other noncurrent assets	102,573	120,476	126,408
Total Assets	7,566,785	7,300,905	7,373,201
Current Liabilities:
Bank overdraft	1,047
Accounts payable	163,597	178,598	192,738
Accrued salaries, benefits and payroll taxes	37,885	47,428	33,463
Pension and postretirement benefits	12,073	9,293	9,658
Accrued insurance and other taxes	70,323	60,093	67,822
Current maturities of long-term debt and short-term facilities	80,038	180,036	228,025
Accrued interest	28,082	16,837	23,060
Other current liabilities	75,458	54,303	50,143
Total Current Liabilities	468,503	546,588	604,909
Long-term debt	1,642,502	1,506,153	1,536,810
Pension, postretirement and postemployment benefits	230,212	248,086	200,152
Deferred income taxes, net	662,982	663,019	676,144
Other noncurrent liabilities	228,604	194,469	196,788
Total Liabilities	3,232,803	3,158,315	3,214,803
Equity:
Common stock, par value $0.01 per share	627	630	633
Preferred stock, par value $0.01 per share
Additional paid-in capital	3,362,744	3,334,461	3,326,531
Accumulated other comprehensive loss	(122,928)	(130,687)	(104,511)
Retained earnings	1,090,778	935,574	932,679
Total Shareholders' Equity	4,331,221	4,139,978	4,155,332
Noncontrolling interests	2,761	2,612	3,066
Total Equity	4,333,982	4,142,590	4,158,398
Total Liabilities and Equity	$ 7,566,785	$ 7,300,905	$ 7,373,201

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Preferred stock, par value	$ 0.01	$ 0.01	$ 0.01

Consolidated Statements of Earnings and Comprehensive Earnings (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net Sales	$ 1,022,137	$ 1,038,344	$ 2,810,110	$ 2,687,740
Freight and delivery revenues	65,595	65,557	185,006	182,194
Total revenues	1,087,732	1,103,901	2,995,116	2,869,934
Cost of sales	730,459	745,037	2,097,272	2,001,752
Freight and delivery costs	65,595	65,557	185,006	182,194
Total cost of revenues	796,054	810,594	2,282,278	2,183,946
Gross Profit	291,678	293,307	712,838	685,988
Selling, general & administrative expenses	57,219	54,773	195,127	172,903
Acquisition-related expenses, net	1,314	306	3,319	853
Other operating expense (income), net	6,181	(4,441)	(2,575)	(7,309)
Earnings from Operations	226,964	242,669	516,967	519,541
Interest expense	23,141	20,568	68,037	60,896
Other nonoperating income, net	(479)	(8,246)	(6,434)	(12,016)
Earnings before taxes on income	204,302	230,347	455,364	470,661
Taxes on income	52,763	70,869	119,277	144,014
Consolidated net earnings	151,539	159,478	336,087	326,647
Less: Net (loss) earnings attributable to noncontrolling interests	(7)	(1)	(72)	121
Net Earnings Attributable to Martin Marietta Materials, Inc.	151,546	159,479	336,159	326,526
Consolidated Comprehensive Earnings: (See Note 1)
Earnings attributable to Martin Marietta Materials, Inc.	154,524	161,036	343,918	327,637
Earnings (Loss) attributable to noncontrolling interests	1	19	(62)	173
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 154,525	$ 161,055	$ 343,856	$ 327,810
Net Earnings Attributable to Martin Marietta Materials, Inc. Per Common Share:
Basic attributable to common shareholders	$ 2.40	$ 2.50	$ 5.33	$ 5.10
Diluted attributable to common shareholders	$ 2.39	$ 2.49	$ 5.30	$ 5.08
Weighted-Average Common Shares Outstanding:
Basic	62,896	63,452	62,940	63,713
Diluted	63,158	63,723	63,218	63,967
Cash Dividends Per Common Share	$ 0.44	$ 0.42	$ 1.28	$ 1.22

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities:
Consolidated net earnings	$ 336,087	$ 326,647
Adjustments to reconcile consolidated net earnings to net cash provided by operating activities:
Depreciation, depletion and amortization	221,418	211,997
Stock-based compensation expense	23,698	17,167
(Gain) Loss on divestitures and sales of assets	(17,970)	158
Deferred income taxes	6,543	59,834
Other items, net	(9,618)	(17,797)
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable, net	(124,622)	(133,848)
Inventories, net	(54,804)	(33,956)
Accounts payable	3,182	12,422
Other assets and liabilities, net	34,484	(20,911)
Net Cash Provided by Operating Activities	418,398	421,713
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(308,745)	(285,481)
Acquisitions, net	(7,200)	(178,689)
Cash received in acquisition		4,246
Proceeds from divestitures and sales of assets	33,138	5,216
Payment of railcar construction advances	(42,954)	(37,370)
Reimbursement of railcar construction advances	40,930	37,370
Net Cash Used for Investing Activities	(284,831)	(454,708)
Cash Flows from Financing Activities:
Borrowings of debt	1,011,244	360,000
Repayments of debt	(975,035)	(168,267)
Payments on capital lease obligations	(2,708)	(2,463)
Debt issuance costs	(1,989)	(213)
Change in bank overdraft	1,047	(10,235)
Contributions by owners of noncontrolling interest	211
Dividends paid	(80,961)	(78,295)
Proceeds from exercise of stock options	10,017	21,876
Shares withheld for employees' income tax obligations	(10,213)	(7,133)
Repurchases of common stock	(99,999)	(190,000)
Net Cash Used for Financing Activities	(148,386)	(74,730)
Net Decrease in Cash and Cash Equivalents	(14,819)	(107,725)
Cash and Cash Equivalents, beginning of period	50,038	168,409
Cash and Cash Equivalents, end of period	$ 35,219	$ 60,684

Consolidated Statement 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, 2015				$ (105,622)
Consolidated net earnings (loss)	$ 326,647
Ending Balance at Sep. 30, 2016	4,158,398			(104,511)
Beginning Balance at Jun. 30, 2016				(106,068)
Consolidated net earnings (loss)	159,478
Ending Balance at Sep. 30, 2016	4,158,398			(104,511)
Beginning Balance at Dec. 31, 2016	4,142,590	$ 630	$ 3,334,461	(130,687)	$ 935,574	$ 4,139,978	$ 2,612
Beginning Balance (in shares) at Dec. 31, 2016		63,176
Consolidated net earnings (loss)	336,087				336,159	336,159	(72)
Other comprehensive earnings, net of tax	7,769			7,759		7,759	10
Dividends declared	(80,961)				(80,961)	(80,961)
Issuances of common stock for stock award plans	4,587	$ 2	4,585			4,587
Issuances of common stock for stock award plans (in shares)		141
Repurchases of common stock	(99,999)	$ (5)			(99,994)	(99,999)
Repurchases of common stock, Shares		(458)
Stock-based compensation expense	23,698		23,698			23,698
Contributions by owners of noncontrolling interest	211						211
Ending Balance at Sep. 30, 2017	4,333,982	$ 627	3,362,744	(122,928)	1,090,778	4,331,221	2,761
Ending Balance (in shares) at Sep. 30, 2017		62,859
Beginning Balance at Jun. 30, 2017				(125,906)
Consolidated net earnings (loss)	151,539
Ending Balance at Sep. 30, 2017	$ 4,333,982	$ 627	$ 3,362,744	$ (122,928)	$ 1,090,778	$ 4,331,221	$ 2,761
Ending Balance (in shares) at Sep. 30, 2017		62,859

Significant Accounting Policies

9 Months Ended

Sep. 30, 2017

Accounting Policies [Abstract]

Significant Accounting Policies

1.	Significant Accounting Policies

Organization

Martin Marietta Materials, Inc. (the Company or Martin Marietta) is engaged principally in the building materials business, including aggregates, cement, ready mixed concrete and asphalt and paving product lines, collectively reported as the Building Materials business. The aggregates product line is sold and shipped from a network of more than 270 quarries and distribution facilities in 26 states, Nova Scotia and the Bahamas. The cement, ready mixed concrete and asphalt and paving product lines are located in strategic, vertically integrated markets, predominantly Texas and Colorado. Building materials are used for construction of highways and other infrastructure projects, and in the nonresidential and residential construction industries. Aggregates and cement products are also used in the railroad, agricultural, utility and environmental industries.

Effective January 1, 2017, the Company reorganized the operations and management reporting structure of its Texas-based aggregates, cement and ready mixed concrete product lines, resulting in a change to its reportable segments. As a result, the cement product line is reported in the West Group. 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, 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 and asphalt and paving

Products and Services	Crushed stone, sand and gravel	Crushed stone, sand and gravel	Crushed stone, sand and gravel; Portland and specialty cements; ready mixed concrete and asphalt and paving

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

1.	Significant Accounting Policies (continued)

Basis of Presentation

The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles 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 adoption of two new accounting pronouncements described below, 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, 2016. 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- and nine-months ended September 30, 2017 are not indicative of the results expected for other interim periods or the full year. The consolidated balance sheet at December 31, 2016 has been derived from the audited consolidated financial statements at that date but does not include all of the information and notes required by generally accepted accounting principles 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, 2016.

New Accounting Pronouncements

Share-Based Payment Accounting

Effective January 1, 2017, the Company adopted Accounting Standards Update (ASU) 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09), which simplifies certain aspects of accounting guidance and requirements for share-based transactions. ASU 2016-09 requires shares withheld for employees’ income tax obligations to be presented as a financing activity in the statement of cash flows, with retrospective presentation. For the nine-months ended September 30, 2016, the Company reclassified a use of $2,635,000 from operating activities to financing activities on the statement of cash flows. Additionally, excess tax benefits from stock-based compensation transactions are presented as an operating activity with retrospective presentation. The Company previously presented excess tax benefits from stock-based compensation transactions as a financing activity and, for the nine-months ended September 30, 2016, reclassified a source of $5,010,000 to operating activities on the statement of cash flows. ASU 2016-09 also requires excess tax benefits and tax deficiencies to be recognized prospectively as income tax benefits or expense in the period awards vest or are exercised. For the three- and nine-months ended September 30, 2017, the Company recognized excess tax benefits of $854,000 and $6,113,000, respectively.

1.	Significant Accounting Policies (continued)

New Accounting Pronouncements

Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

In March 2017, the Financial Accounting Standards Board (FASB) issued ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (ASU 2017-07), which revises the financial statement presentation for periodic pension and postretirement expense or credit, other than service cost. ASU 2017-07 requires net periodic benefit cost or credit, with the exception of service cost, to be presented retrospectively as nonoperating expense. As permitted by ASU 2017-07, the Company used the pension and other postretirement benefit plan disclosures for the comparative prior periods as a practical expedient to estimate amounts for retrospective application. Service cost will remain a component of earnings from operations and represent the only cost of pension and postretirement expense eligible for capitalization, notably in the Company’s inventory standards. The Company early adopted this standard effective January 1, 2017. For the three-months ended September 30, 2016, the Company reclassified $739,000 and $1,575,000 from cost of sales and selling, general and administrative expenses, respectively, to nonoperating expense. For the nine-months ended September 30, 2016, the Company reclassified $2,084,000, $4,815,000 and $774,000 from cost of sales; selling, general and administrative expenses; and other operating income and expenses, respectively, to nonoperating expense.

Pending Accounting Pronouncements

Revenue Recognition Standard

The FASB issued an accounting standards update that amends the accounting guidance on revenue recognition. The new standard intends to provide a more robust framework for addressing revenue issues, improve comparability of revenue recognition practices and improve disclosure requirements. The new standard is effective January 1, 2018 and can be applied on a full retrospective or modified retrospective approach. The Company has completed its initial assessment of the provisions of the new standard and, at this time, does not expect the impact to be material to its results of operations and expects to adopt using the full retrospective approach.

Lease Standard

In February 2016, the FASB issued a new accounting standard, Accounting Codification Standard 842 – Leases, intending to improve financial reporting of leases and to provide more transparency into off-balance sheet leasing obligations. The guidance requires virtually all leases, excluding mineral interest leases, to be recorded on the balance sheet and provides guidance on the recognition of lease expense and income. The new standard is effective January 1, 2019 and must be applied on a modified retrospective approach. The Company is currently assessing the impact of the new standard on the Company’s financial statements. The Company believes the new standard will have a material effect on its balance sheet but has not quantified the impact at this time.

Reclassifications

Prior-year information has been reclassified to conform to the presentation of the Company’s current reportable segments and for the adoption of the two aforementioned accounting pronouncements.

1.	Significant Accounting Policies (continued)

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				Nine-Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	151,546	$	159,479	$	336,159	$	326,526
Other comprehensive earnings, net of tax		2,978		1,557		7,759		1,111
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	154,524	$	161,036	$	343,918	$	327,637

Comprehensive earnings attributable to noncontrolling interests, consisting of net earnings and adjustments for the funded status of pension and postretirement benefit plans, is as follows:

	Three-Months Ended						Nine-Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(Dollars in Thousands)
Net (loss) earnings attributable to noncontrolling interests	$	(7	)	$	(1	)	$	(72	)	$	121
Other comprehensive earnings, net of tax		8			20			10			52
Comprehensive earnings (loss) attributable to noncontrolling interests	$	1		$	19		$	(62	)	$	173

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

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

	(Dollars in Thousands)
							Unamortized
							Value of
							Terminated			Accumulated
	Pension and						Forward Starting			Other
	Postretirement			Foreign			Interest Rate			Comprehensive
	Benefit Plans			Currency			Swap			Loss
	Three-Months Ended September 30, 2017
Balance at beginning of period	$	(124,553	)	$	(636	)	$	(717	)	$	(125,906	)
Other comprehensive earnings before reclassifications, net of tax		—			838			—			838
Amounts reclassified from accumulated other comprehensive earnings, net of tax		1,918			—			222			2,140
Other comprehensive earnings, net of tax		1,918			838			222			2,978
Balance at end of period	$	(122,635	)	$	202		$	(495	)	$	(122,928	)

	Three-Months Ended September 30, 2016
Balance at beginning of period	$	(104,114	)	$	(381	)	$	(1,573	)	$	(106,068	)
Other comprehensive loss before reclassifications, net of tax		—			(198	)		—			(198	)
Amounts reclassified from accumulated other comprehensive earnings, net of tax		1,547			—			208			1,755
Other comprehensive earnings (loss), net of tax		1,547			(198	)		208			1,557
Balance at end of period	$	(102,567	)	$	(579	)	$	(1,365	)	$	(104,511	)

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

	(Dollars in Thousands)
							Unamortized
							Value of
							Terminated			Accumulated
	Pension and						Forward Starting			Other
	Postretirement			Foreign			Interest Rate			Comprehensive
	Benefit Plans			Currency			Swap			Loss
	Nine-Months Ended September 30, 2017
Balance at beginning of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)
Other comprehensive earnings before reclassifications, net of tax		—			1,364			—			1,364
Amounts reclassified from accumulated other comprehensive earnings, net of tax		5,738			—			657			6,395
Other comprehensive earnings, net of tax		5,738			1,364			657			7,759
Balance at end of period	$	(122,635	)	$	202		$	(495	)	$	(122,928	)

	Nine-Months Ended September 30, 2016
Balance at beginning of period	$	(103,380	)	$	(264	)	$	(1,978	)	$	(105,622	)
Other comprehensive loss before reclassifications, net of tax		(3,830	)		(315	)		—			(4,145	)
Amounts reclassified from accumulated other comprehensive earnings, net of tax		4,643			—			613			5,256
Other comprehensive earnings (loss), net of tax		813			(315	)		613			1,111
Balance at end of period	$	(102,567	)	$	(579	)	$	(1,365	)	$	(104,511	)

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

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 September 30, 2017
Balance at beginning of period	$	79,675		$	464		$	80,139
Tax effect of other comprehensive earnings		(1,193	)		(147	)		(1,340	)
Balance at end of period	$	78,482		$	317		$	78,799

	Three-Months Ended September 30, 2016
Balance at beginning of period	$	66,931		$	1,023		$	67,954
Tax effect of other comprehensive earnings		(986	)		(136	)		(1,122	)
Balance at end of period	$	65,945		$	887		$	66,832

	Nine-Months Ended September 30, 2017
Balance at beginning of period	$	82,044		$	749		$	82,793
Tax effect of other comprehensive earnings		(3,562	)		(432	)		(3,994	)
Balance at end of period	$	78,482		$	317		$	78,799

	Nine-Months Ended September 30, 2016
Balance at beginning of period	$	66,467		$	1,290		$	67,757
Tax effect of other comprehensive earnings		(522	)		(403	)		(925	)
Balance at end of period	$	65,945		$	887		$	66,832

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three-Months Ended						Nine-Months Ended						Affected line items in the consolidated
	September 30,						September 30,						statements of earnings and
	2017			2016			2017			2016			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Settlement charge	$	—		$	—		$	—		$	59
Amortization of:
Prior service credit		(402	)		(404	)		(1,070	)		(1,209	)
Actuarial loss		3,513			2,893			10,370			8,681
		3,111			2,489			9,300			7,531		Other nonoperating income, net
Tax benefit		(1,193	)		(942	)		(3,562	)		(2,888	)	Taxes on income
	$	1,918		$	1,547		$	5,738		$	4,643

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	369		$	344		$	1,089		$	1,016		Interest expense
Tax benefit		(147	)		(136	)		(432	)		(403	)	Taxes on income
	$	222		$	208		$	657		$	613

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- and nine-months ended September 30, 2017 and 2016, the diluted per-share computations reflect a change in 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.

1.	Significant Accounting Policies (continued)

Earnings per Common Share

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

	Three-Months Ended				Nine-Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	151,546	$	159,479	$	336,159	$	326,526
Less: Distributed and undistributed earnings attributable to unvested awards		399		637		1,000		1,388
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	151,147	$	158,842	$	335,159	$	325,138

Basic weighted-average common shares outstanding		62,896		63,452		62,940		63,713
Effect of dilutive employee and director awards		262		271		278		254
Diluted weighted-average common shares outstanding		63,158		63,723		63,218		63,967

Goodwill

9 Months Ended

Sep. 30, 2017

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill

	(In Thousands)
	Mid-America		Southeast		West
	Group		Group		Group		Total
Balance at January 1, 2017	$	281,403	$	50,346	$	1,827,588	$	2,159,337
Adjustments to purchase price allocations		—		—		723		723
Balance at September 30, 2017	$	281,403	$	50,346	$	1,828,311	$	2,160,060

The prior-year information has been reclassified to conform to the presentation of the Company’s current reportable segments.

Inventories, Net

9 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Inventories, Net

3.	Inventories, Net

	September 30,			December 31,			September 30,
	2017			2016			2016
	(Dollars in Thousands)
Finished products	$	526,404		$	479,291		$	462,698
Products in process and raw materials		62,449			61,171			61,137
Supplies and expendable parts		126,918			116,024			114,872
		715,771			656,486			638,707
Less: Allowances		(139,342	)		(134,862	)		(130,508	)
Total	$	576,429		$	521,624		$	508,199

Long-Term Debt

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Long-Term Debt

4.	Long-Term Debt

	September 30,			December 31,			September 30,
	2017			2016			2016
	(Dollars in Thousands)
6.60% Senior Notes, due 2018	$	299,774		$	299,483		$	299,388
7% Debentures, due 2025		124,157			124,090			124,068
6.25% Senior Notes, due 2037		228,018			227,975			227,961
4.25% Senior Notes, due 2024		395,673			395,252			395,115
3.450% Senior Notes, due 2027		296,551			—			—
Floating Rate Notes, due 2020, interest rate of 1.96% at September 30, 2017		298,046			—			—
Floating Rate Notes, due 2017, interest rate of 2.10% and 1.94% at December 31, 2016 and September 30, 2016, respectively		—			299,033			298,750
Term Loan Facility, due 2018, interest rate of 1.90% at September 30, 2016		—			—			209,096
Revolving Facility, due 2021, interest rate of 1.86% at December 31, 2016		—			160,000			—
Trade Receivable Facility, interest rate of 1.96%, 1.34% and 1.22% at September 30, 2017, December 31, 2016 and September 30, 2016, respectively		80,000			180,000			210,000
Other notes		321			356			457
Total debt		1,722,540			1,686,189			1,764,835
Less: Current maturities of long-term debt and short-term facilities		(80,038	)		(180,036	)		(228,025	)
Long-term debt	$	1,642,502		$	1,506,153		$	1,536,810

On May 22, 2017, the Company issued $300,000,000 aggregate principal amount of Floating Rate Senior Notes due in 2020 (the Floating Rate Notes) and $300,000,000 principal amount of 3.450% Senior Notes due in 2027 (the 3.450% Senior Notes, and together with the Floating Rate Notes, the Senior Notes). The Senior Notes are senior unsecured obligations of the Company. The 3.450% Senior Notes may be redeemed in whole or in part prior to March 1, 2027 at a make-whole redemption price, or on or after March 1, 2027 at a redemption price equal to 100% of the principal amount of the notes to be redeemed, in either case plus unpaid interest, if any, accrued thereon to, but excluding, the date of redemption. The Floating Rate Notes may not be redeemed prior to their stated maturity date of May 22, 2020. The Floating Rate Notes bear interest at a rate, reset quarterly, equal to the three-month LIBOR for U.S. dollars plus 0.65% (or 65 basis points). If a change of control repurchase event, as defined, occurs, the Company will be required to make an irrevocable offer to repurchase all or, at the election of each holder, any part of the Senior Notes at a repurchase price equal to 101% of their principal amount, plus unpaid interest, if any, accrued thereon to, but excluding, the date of repurchase, unless, in the case of the 3.450% Senior Notes, the Company has exercised its right to redeem such notes in full.

4.	Long-Term Debt (continued)

The Company, through a wholly-owned special-purpose subsidiary, has a $300,000,000 trade receivable securitization facility (the Trade Receivable Facility). On September 27, 2017, the Company extended the maturity of the Trade Receivable Facility to September 26, 2018. 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, of $402,754,000, $333,302,000 and $420,044,000 at September 30, 2017, December 31, 2016 and September 30, 2016, respectively. 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 LIBOR plus 0.725%, subject to change in the event that this rate no longer reflects the lender’s cost of lending. The Trade Receivable Facility contains a cross-default provision to the Company’s other debt agreements.

The Company has a $700,000,000 five-year senior unsecured revolving facility (the Revolving Facility) with JPMorgan Chase Bank, N.A., as Administrative Agent, Branch Banking and Trust Company (BB&T), Deutsche Bank Securities, Inc., SunTrust Bank and Wells Fargo Bank, N.A., as Co-Syndication Agents, and the lenders party thereto. The Revolving Facility requires the Company’s ratio of consolidated debt-to-consolidated earnings before interest, taxes, depreciation, depletion 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 $50,000,000, such reduction not to exceed $200,000,000, for purposes of the covenant calculation. The Company was in compliance with this Ratio at September 30, 2017.

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 $1,962,900 of outstanding letters of credit issued under the Revolving Facility at September 30, 2017 and $2,507,000 at December 31, 2016 and September 30, 2016.

Current maturities of long-term debt and short-term facilities consist of borrowings under the Trade Receivable Facility as well as the current portions of the other notes. The 6.60% Senior Notes, due 2018, have been classified as a noncurrent liability as the Company has the intent and ability to refinance on a long-term basis before or at its maturity on April 15, 2018.

Accumulated other comprehensive loss includes the unamortized value of terminated forward starting interest rate swap agreements. For the three- and nine-months ended September 30, 2017, the Company recognized $369,000 and $1,089,000, respectively, as additional interest expense. For the three- and nine-months ended September 30, 2016, the Company recognized $344,000 and $1,016,000, respectively, as additional interest expense. The ongoing amortization of the terminated value of the forward starting interest rate swap agreements will increase interest expense by approximately $350,000 in the fourth quarter of 2017 and $460,000 during the first four months of 2018 until the related notes mature.

Financial Instruments

9 Months Ended

Sep. 30, 2017

Financial Instruments Disclosure [Abstract]

Financial Instruments

5.	Financial Instruments

The Company’s financial instruments include cash equivalents, accounts receivable, notes receivable, bank overdraft, 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. However, accounts receivable are more heavily concentrated in certain states (namely, Texas, Colorado, North Carolina, Iowa and Georgia). 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.

The bank overdraft represents amounts to be funded to financial institutions for checks that have cleared the bank. The estimated fair value of the bank overdraft approximates its carrying value due to the short-term nature of the overdraft.

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 $1,722,540,000 and $1,830,750,000, respectively, at September 30, 2017; $1,686,189,000 and $1,752,338,000, respectively, at December 31, 2016; and $1,764,835,000 and $1,876,802,000, respectively, at September 30, 2016. The estimated fair value of the publicly-registered long-term notes was estimated based on Level 1 of the fair value hierarchy using quoted market prices. The estimated fair value of other borrowings, which primarily represents variable-rate debt, was based on Level 2 of the fair value hierarchy using quoted market prices for similar debt instruments, and approximates their carrying amounts as the interest rates reset periodically.

Income Taxes

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

Income Taxes

6.	Income Taxes

The Company’s effective income tax rate for the nine-months ended September 30, 2017 was 26.2%. The effective income tax rate reflects the effect of federal and state income taxes and the impact of differences in book and tax accounting arising from the net permanent benefits associated with the statutory depletion deduction for mineral reserves and the domestic production deduction. For the nine-months ended September 30, 2017, as a result of the adoption of ASU 2016-09 (see Note 1), the effective income tax rate reflects the excess tax benefit related to the vesting and exercise of stock-based compensation awards, which are treated as discrete events, and had a favorable impact of 130 basis points on the tax rate. As previously stated in Note 1, this requirement of ASU 2016-09 is prospective and therefore, the prior-year effective income tax rate of 30.6% is not comparable.

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

9 Months Ended

Sep. 30, 2017

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:

	Three-Months Ended September 30,
	Pension						Postretirement Benefits
	2017			2016			2017			2016
	(Dollars in Thousands)
Service cost	$	7,457		$	5,542		$	20		$	22
Interest cost		9,729			8,970			182			216
Expected return on assets		(10,691	)		(9,425	)		—			—
Amortization of:
Prior service cost (credit)		34			87			(436	)		(491	)
Actuarial loss (gain)		3,604			3,018			(91	)		(125	)
Net periodic benefit cost (credit)	$	10,133		$	8,192		$	(325	)	$	(378	)

	Nine-Months Ended September 30,
	Pension						Postretirement Benefits
	2017			2016			2017			2016
	(Dollars in Thousands)
Service cost	$	20,060		$	16,624		$	60		$	65
Interest cost		27,074			26,908			547			648
Expected return on assets		(29,818	)		(28,272	)		—			—
Amortization of:
Prior service cost (credit)		237			262			(1,307	)		(1,471	)
Actuarial loss (gain)		10,643			9,055			(273	)		(374	)
Settlement charge		—			59			—			—
Special termination benefit		—			764			—			(8	)
Net periodic benefit cost (credit)	$	28,196		$	25,400		$	(973	)	$	(1,140	)

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

Commitments and Contingencies

9 Months Ended

Sep. 30, 2017

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 $25,000,000 revolving line of credit agreement with BB&T Bank. 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 $6,000,000 interest-only loan, due December 31, 2019, outstanding from this unconsolidated affiliate as of September 30, 2017, December 31, 2016 and September 30, 2016. The interest rate is one-month LIBOR plus 1.75%.

Business Segments

9 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

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 net sales less cost of sales, 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, expenses for corporate administrative functions, acquisition-related expenses, net, and other nonrecurring and/or non-operational income and expenses excluded from the Company’s evaluation of business segment performance and resource allocation. All debt and related interest expense is held at Corporate.

The following table displays selected financial data for continuing operations for the Company’s reportable business segments. Total revenues and net sales in the table below, as well as the consolidated statements of earnings and comprehensive earnings, exclude intersegment sales which represent net sales from one segment to another segment which are eliminated.

9.	Business Segments (continued)

Effective with a management change previously discussed in Note 1, the cement product line is reported in the West Group. Prior-year segment information has been reclassified to conform to the presentation of the Company’s current reportable segments and for the adoption of ASU 2017-07.

	Three-Months Ended						Nine-Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(Dollars in Thousands)
Total revenues:
Mid-America Group	$	308,472		$	297,275		$	788,390		$	762,297
Southeast Group		94,843			83,814			277,474			243,086
West Group		620,512			657,663			1,726,742			1,671,596
Total Building Materials Business		1,023,827			1,038,752			2,792,606			2,676,979
Magnesia Specialties		63,905			65,149			202,510			192,955
Total	$	1,087,732		$	1,103,901		$	2,995,116		$	2,869,934

Net sales:
Mid-America Group	$	287,078		$	275,791		$	734,258		$	708,151
Southeast Group		91,407			80,044			266,556			230,005
West Group		585,126			622,265			1,622,954			1,570,969
Total Building Materials Business		963,611			978,100			2,623,768			2,509,125
Magnesia Specialties		58,526			60,244			186,342			178,615
Total	$	1,022,137		$	1,038,344		$	2,810,110		$	2,687,740

Earnings (Loss) from operations:
Mid-America Group	$	106,235		$	92,170		$	204,939		$	187,656
Southeast Group		17,882			11,938			42,331			30,579
West Group		96,522			134,559			270,246			299,722
Total Building Materials Business		220,639			238,667			517,516			517,957
Magnesia Specialties		17,590			20,432			58,589			60,319
Corporate		(11,265	)		(16,430	)		(59,138	)		(58,735	)
Total	$	226,964		$	242,669		$	516,967		$	519,541

9.	Business Segments (continued)

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 net sales and gross profit by business: Building Materials (further divided by product line) and Magnesia Specialties.

	Three-Months Ended						Nine-Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(Dollars in Thousands)
Total revenues:
Aggregates	$	647,121		$	637,995		$	1,776,292		$	1,715,457
Cement		91,884			97,287			290,513			287,944
Ready Mixed Concrete		240,456			264,050			705,128			666,506
Asphalt and Paving		150,375			151,141			291,844			253,937
Less: Interproduct Revenues		(106,009	)		(111,721	)		(271,171	)		(246,865	)
Total Building Materials Business		1,023,827			1,038,752			2,792,606			2,676,979
Magnesia Specialties		63,905			65,149			202,510			192,955
Total	$	1,087,732		$	1,103,901		$	2,995,116		$	2,869,934

Net sales:
Aggregates	$	591,195		$	581,536		$	1,620,962		$	1,559,688
Cement		88,615			94,744			281,315			279,045
Ready Mixed Concrete		240,216			263,747			704,491			665,546
Asphalt and Paving		149,594			149,794			288,171			251,712
Less: Interproduct Sales		(106,009	)		(111,721	)		(271,171	)		(246,866	)
Total Building Materials Business		963,611			978,100			2,623,768			2,509,125
Magnesia Specialties		58,526			60,244			186,342			178,615
Total	$	1,022,137		$	1,038,344		$	2,810,110		$	2,687,740

Gross profit (loss):
Aggregates	$	187,947		$	173,891		$	440,711		$	420,972
Cement		27,604			36,871			87,962			93,535
Ready Mixed Concrete		23,907			32,787			70,562			75,987
Asphalt and Paving		28,864			30,247			44,433			36,838
Total Building Materials Business		268,322			273,796			643,668			627,332
Magnesia Specialties		19,910			22,845			65,849			67,564
Corporate		3,446			(3,334	)		3,321			(8,908	)
Total	$	291,678		$	293,307		$	712,838		$	685,988

Other Operating Expense (Income), Net

9 Months Ended

Sep. 30, 2017

Other Income And Expenses [Abstract]

Other Operating Expense (Income), Net

10.	Other Operating Expense (Income), Net

Other operating expense (income), net, for the three-months ended September 30, 2017 reflects a gain on asset retirement obligations offset by a $12,425,000 of nonrecurring repair costs related to certain of the Company’s leased railcars. For the nine-months ended September 30, 2017, other operating expense (income), net, reflects a $13,500,000 gain on the sale of real estate and approximately $7,500,000 of expense, including both cash and stock-based compensation components, related to the retirement of Anne Lloyd, Chief Financial Officer. The vesting of Ms. Lloyd’s shares of restricted stock awards, performance stock awards and stock options will continue on their original vesting schedules, which extend beyond Ms. Lloyd's retirement date. Accordingly, the Company recognized all remaining expense related to the stock-based awards.

Supplemental Cash Flow Information

9 Months Ended

Sep. 30, 2017

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

11.	Supplemental Cash Flow Information

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

	Nine-Months Ended
	September 30,
	2017			2016
	(Dollars in Thousands)
Other current and noncurrent assets	$	(29,342	)	$	(3,997	)
Accrued salaries, benefits and payroll taxes		(6,234	)		413
Accrued insurance and other taxes		10,230			5,041
Accrued income taxes		16,393			693
Accrued pension, postretirement and postemployment benefits		(5,807	)		(21,624	)
Other current and noncurrent liabilities		49,244			(1,437	)
	$	34,484		$	(20,911	)

Noncash investing and financing activities are as follows:

	Nine-Months Ended
	September 30,
	2017		2016
	(Dollars in Thousands)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	20,339	$	24,453
Acquisition of assets through capital lease	$	196	$	998
Settlement of royalty obligation via asset sale	$	900	$	—

11.	Supplemental Cash Flow Information (continued)

Supplemental disclosures of cash flow information are as follows:

	Nine-Months Ended
	September 30,
	2017		2016
	(Dollars in Thousands)
Cash paid for interest	$	49,564	$	48,813
Cash paid for income taxes	$	96,643	$	81,589

Business Combinations

9 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Business Combinations

12.	Business Combinations

In the first quarter 2016, the Company acquired the outstanding stock of Rocky Mountain Materials and Asphalt, Inc., and Rocky Mountain Premix Inc. The acquisition provides more than 500 million tons of mineral reserves and expands the Company’s presence along the Front Range of the Rocky Mountains, home to 80% of Colorado’s population. The acquired operations are reported through the West Group.

In July 2016, the Company acquired the remaining interest in Ratliff Ready-Mix, L.P. (Ratliff), which operates ready mixed concrete plants in central Texas. Prior to the acquisition, the Company owned a 40% interest in Ratliff which was accounted for under the equity method. The Company was required to re-measure the existing 40% interest to fair value upon closing of the transaction, resulting in a gain of $5,863,000, which was recorded in other nonoperating income in third quarter 2016. These operations are reported in the West Group.

The impact of these acquisitions on the operating results was not considered material; therefore, pro forma financial information is not included.

Pending Acquisition of Bluegrass Materials

9 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Pending Acquisition of Bluegrass Materials

13.	Pending Acquisition of Bluegrass Materials

On June 26, 2017, the Company announced a definitive agreement to acquire Bluegrass Materials Company (Bluegrass) for $1,625,000,000 in cash. The Company will not acquire any of Bluegrass’ cash and cash equivalents nor will it assume any of Bluegrass’ outstanding debt. Bluegrass is the largest privately held, pure-play aggregates business in the United States and has a portfolio of 23 active sites with more than 125 years of strategically-located, high-quality reserves, in Georgia, South Carolina, Tennessee, Maryland and Kentucky. These operations complement the Company’s existing southeastern footprint and provides a new growth platform within the southern portion of the Northeast Megaregion. The Company and Bluegrass are continuing to work closely and cooperatively with the Department of Justice in its review of the proposed transaction. The parties currently anticipate that the proposed acquisition will be completed in the first half of 2018.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2017

Accounting Policies [Abstract]

Organization

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, 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 and asphalt and paving

Products and Services	Crushed stone, sand and gravel	Crushed stone, sand and gravel	Crushed stone, sand and gravel; Portland and specialty cements; ready mixed concrete and asphalt and paving

Basis of Presentation

New Accounting Pronouncements

Share-Based Payment Accounting

1.	Significant Accounting Policies (continued)

New Accounting Pronouncements

Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

Pending Accounting Pronouncements

Revenue Recognition Standard

Lease Standard

Reclassifications

Prior-year information has been reclassified to conform to the presentation of the Company’s current reportable segments and for the adoption of the two aforementioned accounting pronouncements.

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three-Months Ended				Nine-Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	151,546	$	159,479	$	336,159	$	326,526
Other comprehensive earnings, net of tax		2,978		1,557		7,759		1,111
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	154,524	$	161,036	$	343,918	$	327,637

Comprehensive earnings attributable to noncontrolling interests, consisting of net earnings and adjustments for the funded status of pension and postretirement benefit plans, is as follows:

	Three-Months Ended						Nine-Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(Dollars in Thousands)
Net (loss) earnings attributable to noncontrolling interests	$	(7	)	$	(1	)	$	(72	)	$	121
Other comprehensive earnings, net of tax		8			20			10			52
Comprehensive earnings (loss) attributable to noncontrolling interests	$	1		$	19		$	(62	)	$	173

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

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

	(Dollars in Thousands)
							Unamortized
							Value of
							Terminated			Accumulated
	Pension and						Forward Starting			Other
	Postretirement			Foreign			Interest Rate			Comprehensive
	Benefit Plans			Currency			Swap			Loss
	Three-Months Ended September 30, 2017
Balance at beginning of period	$	(124,553	)	$	(636	)	$	(717	)	$	(125,906	)
Other comprehensive earnings before reclassifications, net of tax		—			838			—			838
Amounts reclassified from accumulated other comprehensive earnings, net of tax		1,918			—			222			2,140
Other comprehensive earnings, net of tax		1,918			838			222			2,978
Balance at end of period	$	(122,635	)	$	202		$	(495	)	$	(122,928	)

	Three-Months Ended September 30, 2016
Balance at beginning of period	$	(104,114	)	$	(381	)	$	(1,573	)	$	(106,068	)
Other comprehensive loss before reclassifications, net of tax		—			(198	)		—			(198	)
Amounts reclassified from accumulated other comprehensive earnings, net of tax		1,547			—			208			1,755
Other comprehensive earnings (loss), net of tax		1,547			(198	)		208			1,557
Balance at end of period	$	(102,567	)	$	(579	)	$	(1,365	)	$	(104,511	)

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

	(Dollars in Thousands)
							Unamortized
							Value of
							Terminated			Accumulated
	Pension and						Forward Starting			Other
	Postretirement			Foreign			Interest Rate			Comprehensive
	Benefit Plans			Currency			Swap			Loss
	Nine-Months Ended September 30, 2017
Balance at beginning of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)
Other comprehensive earnings before reclassifications, net of tax		—			1,364			—			1,364
Amounts reclassified from accumulated other comprehensive earnings, net of tax		5,738			—			657			6,395
Other comprehensive earnings, net of tax		5,738			1,364			657			7,759
Balance at end of period	$	(122,635	)	$	202		$	(495	)	$	(122,928	)

	Nine-Months Ended September 30, 2016
Balance at beginning of period	$	(103,380	)	$	(264	)	$	(1,978	)	$	(105,622	)
Other comprehensive loss before reclassifications, net of tax		(3,830	)		(315	)		—			(4,145	)
Amounts reclassified from accumulated other comprehensive earnings, net of tax		4,643			—			613			5,256
Other comprehensive earnings (loss), net of tax		813			(315	)		613			1,111
Balance at end of period	$	(102,567	)	$	(579	)	$	(1,365	)	$	(104,511	)

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

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 September 30, 2017
Balance at beginning of period	$	79,675		$	464		$	80,139
Tax effect of other comprehensive earnings		(1,193	)		(147	)		(1,340	)
Balance at end of period	$	78,482		$	317		$	78,799

	Three-Months Ended September 30, 2016
Balance at beginning of period	$	66,931		$	1,023		$	67,954
Tax effect of other comprehensive earnings		(986	)		(136	)		(1,122	)
Balance at end of period	$	65,945		$	887		$	66,832

	Nine-Months Ended September 30, 2017
Balance at beginning of period	$	82,044		$	749		$	82,793
Tax effect of other comprehensive earnings		(3,562	)		(432	)		(3,994	)
Balance at end of period	$	78,482		$	317		$	78,799

	Nine-Months Ended September 30, 2016
Balance at beginning of period	$	66,467		$	1,290		$	67,757
Tax effect of other comprehensive earnings		(522	)		(403	)		(925	)
Balance at end of period	$	65,945		$	887		$	66,832

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three-Months Ended						Nine-Months Ended						Affected line items in the consolidated
	September 30,						September 30,						statements of earnings and
	2017			2016			2017			2016			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Settlement charge	$	—		$	—		$	—		$	59
Amortization of:
Prior service credit		(402	)		(404	)		(1,070	)		(1,209	)
Actuarial loss		3,513			2,893			10,370			8,681
		3,111			2,489			9,300			7,531		Other nonoperating income, net
Tax benefit		(1,193	)		(942	)		(3,562	)		(2,888	)	Taxes on income
	$	1,918		$	1,547		$	5,738		$	4,643

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	369		$	344		$	1,089		$	1,016		Interest expense
Tax benefit		(147	)		(136	)		(432	)		(403	)	Taxes on income
	$	222		$	208		$	657		$	613

Earnings per Common Share

1.	Significant Accounting Policies (continued)

Earnings per Common Share

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

	Three-Months Ended				Nine-Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	151,546	$	159,479	$	336,159	$	326,526
Less: Distributed and undistributed earnings attributable to unvested awards		399		637		1,000		1,388
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	151,147	$	158,842	$	335,159	$	325,138

Basic weighted-average common shares outstanding		62,896		63,452		62,940		63,713
Effect of dilutive employee and director awards		262		271		278		254
Diluted weighted-average common shares outstanding		63,158		63,723		63,218		63,967

Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2017

Significant Accounting Policies [Line Items]

Changes in Accumulated Other Comprehensive Earnings (Loss), Net of Tax

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

	(Dollars in Thousands)
							Unamortized
							Value of
							Terminated			Accumulated
	Pension and						Forward Starting			Other
	Postretirement			Foreign			Interest Rate			Comprehensive
	Benefit Plans			Currency			Swap			Loss
	Three-Months Ended September 30, 2017
Balance at beginning of period	$	(124,553	)	$	(636	)	$	(717	)	$	(125,906	)
Other comprehensive earnings before reclassifications, net of tax		—			838			—			838
Amounts reclassified from accumulated other comprehensive earnings, net of tax		1,918			—			222			2,140
Other comprehensive earnings, net of tax		1,918			838			222			2,978
Balance at end of period	$	(122,635	)	$	202		$	(495	)	$	(122,928	)

	Three-Months Ended September 30, 2016
Balance at beginning of period	$	(104,114	)	$	(381	)	$	(1,573	)	$	(106,068	)
Other comprehensive loss before reclassifications, net of tax		—			(198	)		—			(198	)
Amounts reclassified from accumulated other comprehensive earnings, net of tax		1,547			—			208			1,755
Other comprehensive earnings (loss), net of tax		1,547			(198	)		208			1,557
Balance at end of period	$	(102,567	)	$	(579	)	$	(1,365	)	$	(104,511	)

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

	(Dollars in Thousands)
							Unamortized
							Value of
							Terminated			Accumulated
	Pension and						Forward Starting			Other
	Postretirement			Foreign			Interest Rate			Comprehensive
	Benefit Plans			Currency			Swap			Loss
	Nine-Months Ended September 30, 2017
Balance at beginning of period	$	(128,373	)	$	(1,162	)	$	(1,152	)	$	(130,687	)
Other comprehensive earnings before reclassifications, net of tax		—			1,364			—			1,364
Amounts reclassified from accumulated other comprehensive earnings, net of tax		5,738			—			657			6,395
Other comprehensive earnings, net of tax		5,738			1,364			657			7,759
Balance at end of period	$	(122,635	)	$	202		$	(495	)	$	(122,928	)

	Nine-Months Ended September 30, 2016
Balance at beginning of period	$	(103,380	)	$	(264	)	$	(1,978	)	$	(105,622	)
Other comprehensive loss before reclassifications, net of tax		(3,830	)		(315	)		—			(4,145	)
Amounts reclassified from accumulated other comprehensive earnings, net of tax		4,643			—			613			5,256
Other comprehensive earnings (loss), net of tax		813			(315	)		613			1,111
Balance at end of period	$	(102,567	)	$	(579	)	$	(1,365	)	$	(104,511	)

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 September 30, 2017
Balance at beginning of period	$	79,675		$	464		$	80,139
Tax effect of other comprehensive earnings		(1,193	)		(147	)		(1,340	)
Balance at end of period	$	78,482		$	317		$	78,799

	Three-Months Ended September 30, 2016
Balance at beginning of period	$	66,931		$	1,023		$	67,954
Tax effect of other comprehensive earnings		(986	)		(136	)		(1,122	)
Balance at end of period	$	65,945		$	887		$	66,832

	Nine-Months Ended September 30, 2017
Balance at beginning of period	$	82,044		$	749		$	82,793
Tax effect of other comprehensive earnings		(3,562	)		(432	)		(3,994	)
Balance at end of period	$	78,482		$	317		$	78,799

	Nine-Months Ended September 30, 2016
Balance at beginning of period	$	66,467		$	1,290		$	67,757
Tax effect of other comprehensive earnings		(522	)		(403	)		(925	)
Balance at end of period	$	65,945		$	887		$	66,832

Reclassification Out of Accumulated Other Comprehensive Loss

1.	Significant Accounting Policies (continued)

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss (continued)

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three-Months Ended						Nine-Months Ended						Affected line items in the consolidated
	September 30,						September 30,						statements of earnings and
	2017			2016			2017			2016			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Settlement charge	$	—		$	—		$	—		$	59
Amortization of:
Prior service credit		(402	)		(404	)		(1,070	)		(1,209	)
Actuarial loss		3,513			2,893			10,370			8,681
		3,111			2,489			9,300			7,531		Other nonoperating income, net
Tax benefit		(1,193	)		(942	)		(3,562	)		(2,888	)	Taxes on income
	$	1,918		$	1,547		$	5,738		$	4,643

Unamortized value of terminated forward starting interest rate swap
Additional interest expense	$	369		$	344		$	1,089		$	1,016		Interest expense
Tax benefit		(147	)		(136	)		(432	)		(403	)	Taxes on income
	$	222		$	208		$	657		$	613

Basic and Diluted Earnings Per Common Share

1.	Significant Accounting Policies (continued)

Earnings per Common Share

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

	Three-Months Ended				Nine-Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(In Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	151,546	$	159,479	$	336,159	$	326,526
Less: Distributed and undistributed earnings attributable to unvested awards		399		637		1,000		1,388
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	151,147	$	158,842	$	335,159	$	325,138

Basic weighted-average common shares outstanding		62,896		63,452		62,940		63,713
Effect of dilutive employee and director awards		262		271		278		254
Diluted weighted-average common shares outstanding		63,158		63,723		63,218		63,967

Parent

Significant Accounting Policies [Line Items]

Comprehensive Earnings

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three-Months Ended				Nine-Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	151,546	$	159,479	$	336,159	$	326,526
Other comprehensive earnings, net of tax		2,978		1,557		7,759		1,111
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	154,524	$	161,036	$	343,918	$	327,637

Noncontrolling Interests

Significant Accounting Policies [Line Items]

Comprehensive Earnings

Comprehensive earnings attributable to noncontrolling interests, consisting of net earnings and adjustments for the funded status of pension and postretirement benefit plans, is as follows:

	Three-Months Ended						Nine-Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(Dollars in Thousands)
Net (loss) earnings attributable to noncontrolling interests	$	(7	)	$	(1	)	$	(72	)	$	121
Other comprehensive earnings, net of tax		8			20			10			52
Comprehensive earnings (loss) attributable to noncontrolling interests	$	1		$	19		$	(62	)	$	173

Goodwill (Tables)

9 Months Ended

Sep. 30, 2017

Goodwill And Intangible Assets Disclosure [Abstract]

Changes in Goodwill

	(In Thousands)
	Mid-America		Southeast		West
	Group		Group		Group		Total
Balance at January 1, 2017	$	281,403	$	50,346	$	1,827,588	$	2,159,337
Adjustments to purchase price allocations		—		—		723		723
Balance at September 30, 2017	$	281,403	$	50,346	$	1,828,311	$	2,160,060

Inventories, Net (Tables)

9 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Schedule of Inventories Net

	September 30,			December 31,			September 30,
	2017			2016			2016
	(Dollars in Thousands)
Finished products	$	526,404		$	479,291		$	462,698
Products in process and raw materials		62,449			61,171			61,137
Supplies and expendable parts		126,918			116,024			114,872
		715,771			656,486			638,707
Less: Allowances		(139,342	)		(134,862	)		(130,508	)
Total	$	576,429		$	521,624		$	508,199

Long-Term Debt (Tables)

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Long-Term Debt

	September 30,			December 31,			September 30,
	2017			2016			2016
	(Dollars in Thousands)
6.60% Senior Notes, due 2018	$	299,774		$	299,483		$	299,388
7% Debentures, due 2025		124,157			124,090			124,068
6.25% Senior Notes, due 2037		228,018			227,975			227,961
4.25% Senior Notes, due 2024		395,673			395,252			395,115
3.450% Senior Notes, due 2027		296,551			—			—
Floating Rate Notes, due 2020, interest rate of 1.96% at September 30, 2017		298,046			—			—
Floating Rate Notes, due 2017, interest rate of 2.10% and 1.94% at December 31, 2016 and September 30, 2016, respectively		—			299,033			298,750
Term Loan Facility, due 2018, interest rate of 1.90% at September 30, 2016		—			—			209,096
Revolving Facility, due 2021, interest rate of 1.86% at December 31, 2016		—			160,000			—
Trade Receivable Facility, interest rate of 1.96%, 1.34% and 1.22% at September 30, 2017, December 31, 2016 and September 30, 2016, respectively		80,000			180,000			210,000
Other notes		321			356			457
Total debt		1,722,540			1,686,189			1,764,835
Less: Current maturities of long-term debt and short-term facilities		(80,038	)		(180,036	)		(228,025	)
Long-term debt	$	1,642,502		$	1,506,153		$	1,536,810

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Pension and Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2017

Compensation And Retirement Disclosure [Abstract]

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:

	Three-Months Ended September 30,
	Pension						Postretirement Benefits
	2017			2016			2017			2016
	(Dollars in Thousands)
Service cost	$	7,457		$	5,542		$	20		$	22
Interest cost		9,729			8,970			182			216
Expected return on assets		(10,691	)		(9,425	)		—			—
Amortization of:
Prior service cost (credit)		34			87			(436	)		(491	)
Actuarial loss (gain)		3,604			3,018			(91	)		(125	)
Net periodic benefit cost (credit)	$	10,133		$	8,192		$	(325	)	$	(378	)

	Nine-Months Ended September 30,
	Pension						Postretirement Benefits
	2017			2016			2017			2016
	(Dollars in Thousands)
Service cost	$	20,060		$	16,624		$	60		$	65
Interest cost		27,074			26,908			547			648
Expected return on assets		(29,818	)		(28,272	)		—			—
Amortization of:
Prior service cost (credit)		237			262			(1,307	)		(1,471	)
Actuarial loss (gain)		10,643			9,055			(273	)		(374	)
Settlement charge		—			59			—			—
Special termination benefit		—			764			—			(8	)
Net periodic benefit cost (credit)	$	28,196		$	25,400		$	(973	)	$	(1,140	)

Business Segments (Tables)

9 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

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

	Three-Months Ended						Nine-Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(Dollars in Thousands)
Total revenues:
Mid-America Group	$	308,472		$	297,275		$	788,390		$	762,297
Southeast Group		94,843			83,814			277,474			243,086
West Group		620,512			657,663			1,726,742			1,671,596
Total Building Materials Business		1,023,827			1,038,752			2,792,606			2,676,979
Magnesia Specialties		63,905			65,149			202,510			192,955
Total	$	1,087,732		$	1,103,901		$	2,995,116		$	2,869,934

Net sales:
Mid-America Group	$	287,078		$	275,791		$	734,258		$	708,151
Southeast Group		91,407			80,044			266,556			230,005
West Group		585,126			622,265			1,622,954			1,570,969
Total Building Materials Business		963,611			978,100			2,623,768			2,509,125
Magnesia Specialties		58,526			60,244			186,342			178,615
Total	$	1,022,137		$	1,038,344		$	2,810,110		$	2,687,740

Earnings (Loss) from operations:
Mid-America Group	$	106,235		$	92,170		$	204,939		$	187,656
Southeast Group		17,882			11,938			42,331			30,579
West Group		96,522			134,559			270,246			299,722
Total Building Materials Business		220,639			238,667			517,516			517,957
Magnesia Specialties		17,590			20,432			58,589			60,319
Corporate		(11,265	)		(16,430	)		(59,138	)		(58,735	)
Total	$	226,964		$	242,669		$	516,967		$	519,541

Net Sales and Gross Profit by Line of Business

	Three-Months Ended						Nine-Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(Dollars in Thousands)
Total revenues:
Aggregates	$	647,121		$	637,995		$	1,776,292		$	1,715,457
Cement		91,884			97,287			290,513			287,944
Ready Mixed Concrete		240,456			264,050			705,128			666,506
Asphalt and Paving		150,375			151,141			291,844			253,937
Less: Interproduct Revenues		(106,009	)		(111,721	)		(271,171	)		(246,865	)
Total Building Materials Business		1,023,827			1,038,752			2,792,606			2,676,979
Magnesia Specialties		63,905			65,149			202,510			192,955
Total	$	1,087,732		$	1,103,901		$	2,995,116		$	2,869,934

Net sales:
Aggregates	$	591,195		$	581,536		$	1,620,962		$	1,559,688
Cement		88,615			94,744			281,315			279,045
Ready Mixed Concrete		240,216			263,747			704,491			665,546
Asphalt and Paving		149,594			149,794			288,171			251,712
Less: Interproduct Sales		(106,009	)		(111,721	)		(271,171	)		(246,866	)
Total Building Materials Business		963,611			978,100			2,623,768			2,509,125
Magnesia Specialties		58,526			60,244			186,342			178,615
Total	$	1,022,137		$	1,038,344		$	2,810,110		$	2,687,740

Gross profit (loss):
Aggregates	$	187,947		$	173,891		$	440,711		$	420,972
Cement		27,604			36,871			87,962			93,535
Ready Mixed Concrete		23,907			32,787			70,562			75,987
Asphalt and Paving		28,864			30,247			44,433			36,838
Total Building Materials Business		268,322			273,796			643,668			627,332
Magnesia Specialties		19,910			22,845			65,849			67,564
Corporate		3,446			(3,334	)		3,321			(8,908	)
Total	$	291,678		$	293,307		$	712,838		$	685,988

Supplemental Cash Flow Information (Tables)

9 Months Ended

Sep. 30, 2017

Supplemental Cash Flow Elements [Abstract]

Components of Change in Other Assets and Liabilities, Net

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

	Nine-Months Ended
	September 30,
	2017			2016
	(Dollars in Thousands)
Other current and noncurrent assets	$	(29,342	)	$	(3,997	)
Accrued salaries, benefits and payroll taxes		(6,234	)		413
Accrued insurance and other taxes		10,230			5,041
Accrued income taxes		16,393			693
Accrued pension, postretirement and postemployment benefits		(5,807	)		(21,624	)
Other current and noncurrent liabilities		49,244			(1,437	)
	$	34,484		$	(20,911	)

Schedule Of Noncash Investing and Financing Activities

Noncash investing and financing activities are as follows:

	Nine-Months Ended
	September 30,
	2017		2016
	(Dollars in Thousands)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	20,339	$	24,453
Acquisition of assets through capital lease	$	196	$	998
Settlement of royalty obligation via asset sale	$	900	$	—

Supplemental Disclosures of Cash Flow Information

11.	Supplemental Cash Flow Information (continued)

Supplemental disclosures of cash flow information are as follows:

	Nine-Months Ended
	September 30,
	2017		2016
	(Dollars in Thousands)
Cash paid for interest	$	49,564	$	48,813
Cash paid for income taxes	$	96,643	$	81,589

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) State	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Facility State Segment	Sep. 30, 2016 USD ($)
Significant Accounting Policies [Line Items]
Number of states with aggregates business sales by destination \| State	26		26
Number of reportable segments \| Segment			3
Shares withheld for income tax obligations reclassified from operating activity to financing activity			$ 10,213,000	$ 7,133,000
ASU 2016-09
Significant Accounting Policies [Line Items]
Shares withheld for income tax obligations reclassified from operating activity to financing activity				2,635,000
Excess tax benefits from stock-based compensation recognized as operating activities	$ 854,000		$ 6,113,000	5,010,000
ASU 2017-07 \| Cost of Sales
Significant Accounting Policies [Line Items]
Reclassification of costs to nonoperating expense		$ 739,000		2,084,000
ASU 2017-07 \| Selling, General and Administrative Expenses
Significant Accounting Policies [Line Items]
Reclassification of costs to nonoperating expense		$ 1,575,000		4,815,000
ASU 2017-07 \| Other Operating Income and Expenses
Significant Accounting Policies [Line Items]
Reclassification of costs to nonoperating expense				$ 774,000
Minimum
Significant Accounting Policies [Line Items]
Number of quarries distribution facilities and plants \| Facility			270

Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 151,546	$ 159,479	$ 336,159	$ 326,526
Other comprehensive earnings, net of tax	2,978	1,557	7,759	1,111
Earnings attributable to Martin Marietta Materials, Inc.	$ 154,524	$ 161,036	$ 343,918	$ 327,637

Comprehensive Earnings Attributable to Noncontrolling Interests (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) earnings attributable to noncontrolling interests	$ (7)	$ (1)	$ (72)	$ 121
Other comprehensive earnings, net of tax	8	20	10	52
Comprehensive earnings (loss) attributable to noncontrolling interests	$ 1	$ 19	$ (62)	$ 173

Changes in Accumulated Other Comprehensive Earnings (Loss), Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 4,142,590
Other comprehensive earnings (loss) before reclassifications, net of tax	$ 838	$ (198)	1,364	$ (4,145)
Amounts reclassified from accumulated other comprehensive earnings, net of tax	2,140	1,755	6,395	5,256
Other comprehensive earnings (loss), net of tax	2,978	1,557	7,759	1,111
Ending Balance	4,333,982	4,158,398	4,333,982	4,158,398
Pension and Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(124,553)	(104,114)	(128,373)	(103,380)
Other comprehensive earnings (loss) before reclassifications, net of tax				(3,830)
Amounts reclassified from accumulated other comprehensive earnings, net of tax	1,918	1,547	5,738	4,643
Other comprehensive earnings (loss), net of tax	1,918	1,547	5,738	813
Ending Balance	(122,635)	(102,567)	(122,635)	(102,567)
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(636)	(381)	(1,162)	(264)
Other comprehensive earnings (loss) before reclassifications, net of tax	838	(198)	1,364	(315)
Other comprehensive earnings (loss), net of tax	838	(198)	1,364	(315)
Ending Balance	202	(579)	202	(579)
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(717)	(1,573)	(1,152)	(1,978)
Amounts reclassified from accumulated other comprehensive earnings, net of tax	222	208	657	613
Other comprehensive earnings (loss), net of tax	222	208	657	613
Ending Balance	(495)	(1,365)	(495)	(1,365)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(125,906)	(106,068)	(130,687)	(105,622)
Ending Balance	$ (122,928)	$ (104,511)	$ (122,928)	$ (104,511)

Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 79,675	$ 66,931	$ 82,044	$ 66,467
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans	(1,193)	(986)	(3,562)	(522)
Balance at end of period, Pension and Postretirement Benefit Plans	78,482	65,945	78,482	65,945
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	464	1,023	749	1,290
Tax effect of other comprehensive earnings, Unamortized Value of Terminated Forward Starting Interest Rate Swap	(147)	(136)	(432)	(403)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	317	887	317	887
Balance at beginning of period, Net Noncurrent Deferred Tax Assets	80,139	67,954	82,793	67,757
Tax effect of other comprehensive earnings, Net Noncurrent Deferred Tax Assets	(1,340)	(1,122)	(3,994)	(925)
Balance at end of period, Net Noncurrent Deferred Tax Assets	$ 78,799	$ 66,832	$ 78,799	$ 66,832

Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Additional interest expense	$ 23,141	$ 20,568	$ 68,037	$ 60,896
Tax benefit	52,763	70,869	119,277	144,014
Earnings from Continuing Operations	2,140	1,755	6,395	5,256
Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	1,918	1,547	5,738	4,643
Unamortized Value of Terminated Forward Starting Interest Rate Swap
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	222	208	657	613
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Settlement charge				59
Prior service credit	(402)	(404)	(1,070)	(1,209)
Actuarial loss	3,513	2,893	10,370	8,681
Tax benefit	(1,193)	(942)	(3,562)	(2,888)
Earnings from Continuing Operations	1,918	1,547	5,738	4,643
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	3,111	2,489	9,300	7,531
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	369	344	1,089	1,016
Tax benefit	(147)	(136)	(432)	(403)
Earnings from Continuing Operations	$ 222	$ 208	$ 657	$ 613

Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 151,546	$ 159,479	$ 336,159	$ 326,526
Less: Distributed and undistributed earnings attributable to unvested awards	399	637	1,000	1,388
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 151,147	$ 158,842	$ 335,159	$ 325,138
Basic weighted-average common shares outstanding	62,896	63,452	62,940	63,713
Effect of dilutive employee and director awards	262	271	278	254
Diluted weighted-average common shares outstanding	63,158	63,723	63,218	63,967

Changes in Goodwill (Detail) $ in Thousands	9 Months Ended
Changes in Goodwill (Detail) $ in Thousands	Sep. 30, 2017 USD ($)
Goodwill [Line Items]
Balance at beginning of period	$ 2,159,337
Adjustments to purchase price allocations	723
Balance at end of period	2,160,060
Mid-America Group
Goodwill [Line Items]
Balance at beginning of period	281,403
Balance at end of period	281,403
Southeast Group
Goodwill [Line Items]
Balance at beginning of period	50,346
Balance at end of period	50,346
West Group
Goodwill [Line Items]
Balance at beginning of period	1,827,588
Adjustments to purchase price allocations	723
Balance at end of period	$ 1,828,311

Schedule of Inventories Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Inventory Disclosure [Abstract]
Finished products	$ 526,404	$ 479,291	$ 462,698
Products in process and raw materials	62,449	61,171	61,137
Supplies and expendable parts	126,918	116,024	114,872
Inventories, Gross	715,771	656,486	638,707
Less: Allowances	(139,342)	(134,862)	(130,508)
Total	$ 576,429	$ 521,624	$ 508,199

Long-Term Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Debt Instrument [Line Items]
Total debt	$ 1,722,540	$ 1,686,189	$ 1,764,835
Less: Current maturities of long-term debt and short-term facilities	(80,038)	(180,036)	(228,025)
Long-term debt	1,642,502	1,506,153	1,536,810
Revolving Facility, Due 2021
Debt Instrument [Line Items]
Total debt		160,000
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Total debt	299,774	299,483	299,388
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total debt	124,157	124,090	124,068
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total debt	228,018	227,975	227,961
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	395,673	395,252	395,115
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	296,551
Floating Rate Notes, Due 2017
Debt Instrument [Line Items]
Total debt		299,033	298,750
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Total debt	298,046
Term Loan Facility, Due 2018
Debt Instrument [Line Items]
Total debt			209,096
Trade Receivable Facility
Debt Instrument [Line Items]
Total debt	80,000	180,000	210,000
Other Notes
Debt Instrument [Line Items]
Total debt	$ 321	$ 356	$ 457

Long-Term Debt (Parenthetical) (Detail)		9 Months Ended
Long-Term Debt (Parenthetical) (Detail)	May 22, 2017	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Revolving Facility, Due 2021
Debt Instrument [Line Items]
Maturity year		2021
Credit Facility interest rate			1.86%
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Maturity year		2018
Interest rate on notes		6.60%
7% Debentures, Due 2025
Debt Instrument [Line Items]
Maturity year		2025
Interest rate on notes		7.00%
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Maturity year		2037
Interest rate on notes		6.25%
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Maturity year		2024
Interest rate on notes		4.25%
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year		2027
Interest rate on notes		3.45%
Floating Rate Notes, Due 2017
Debt Instrument [Line Items]
Maturity year		2017
Interest rate			2.10%	1.94%
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Maturity year	2020	2020
Interest rate		1.96%
Term Loan Facility, Due 2018
Debt Instrument [Line Items]
Maturity year		2018
Interest rate				1.90%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit Facility interest rate		1.96%	1.34%	1.22%

Long-Term Debt - Additional information (Detail)			3 Months Ended			4 Months Ended	9 Months Ended
Long-Term Debt - Additional information (Detail)	Sep. 27, 2017 USD ($)	May 22, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Apr. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Redemption price percentage of principal amount of notes redeemed		100.00%
Required offer price to repurchase senior notes if change of control repurchase event							101.00%
Maximum consolidated debt reduction for unrestricted cash and cash equivalents for debt covenant calculation							$ 200,000,000
Additional interest expense				$ 369,000	$ 344,000		1,089,000	$ 1,016,000
Scenario, Forecast
Debt Instrument [Line Items]
Increase in interest expense due to ongoing amortization of the terminated value of the swap agreements			$ 350,000			$ 460,000
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			3.50
Excluding Acquisition Bridge Debt \| Maximum
Debt Instrument [Line Items]
Debt covenant				3.75			3.75
Revolving Facility
Debt Instrument [Line Items]
Credit facility commitment				$ 700,000,000			$ 700,000,000
Senior unsecured revolving facility, maturity period							5 years
Outstanding letters of credit				1,962,900	2,507,000		$ 1,962,900	2,507,000	$ 2,507,000
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Senior notes, principal amount		$ 300,000,000
Maturity year		2020					2020
Debt instrument, maturity date							May 22, 2020
3.45% Senior Notes, Due 2027
Debt Instrument [Line Items]
Senior notes, principal amount		$ 300,000,000
Maturity year		2027
Interest rate on notes		3.45%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit facility commitment	$ 300,000,000
Debt instrument maturity period	Sep. 26, 2018
Credit facility borrowing base				$ 402,754,000	$ 420,044,000		$ 402,754,000	$ 420,044,000	$ 333,302,000
6.65% Senior Notes, Due 2018
Debt Instrument [Line Items]
Maturity year							2018
Interest rate on notes				6.60%			6.60%
Debt instrument, maturity date							Apr. 15, 2018
Debt instrument maturity, description							The 6.60% Senior Notes, due 2018, have been classified as a noncurrent liability as the Company has the intent and ability to refinance on a long-term basis before or at its maturity on April 15, 2018.
Three-month LIBOR \| Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Basis spread on variable rate		0.65%
London Interbank Offered Rate(LIBOR) \| Trade Receivable Facility
Debt Instrument [Line Items]
Basis spread on variable rate							0.725%
Debt Instrument, Redemption, Period One \| 3.45% Senior Notes, Due 2027
Debt Instrument [Line Items]
Debt instrument, redemption description							The 3.450% Senior Notes may be redeemed in whole or in part prior to March 1, 2027 at a make-whole redemption price
Debt Instrument, Redemption, Period Two \| 3.45% Senior Notes, Due 2027
Debt Instrument [Line Items]
Debt instrument, redemption description							or on or after March 1, 2027 at a redemption price equal to 100% of the principal amount of the notes to be redeemed, in either case plus unpaid interest, if any, accrued thereon to, but excluding, the date of redemption.

Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Long-term debt, carrying values	$ 1,722,540	$ 1,686,189	$ 1,764,835
Long-term debt, fair values	$ 1,830,750	$ 1,752,338	$ 1,876,802

Income Taxes - Additional Information (Detail)	9 Months Ended	12 Months Ended
Income Taxes - Additional Information (Detail)	Sep. 30, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Effective income tax rate	26.20%	30.60%
Adoption of ASU 2016-09
Income Taxes [Line Items]
Favorable basis points on tax rate related to vesting and exercise of stock-based compensation awards	1.30%

Schedule of Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,457	$ 5,542	$ 20,060	$ 16,624
Interest cost	9,729	8,970	27,074	26,908
Expected return on assets	(10,691)	(9,425)	(29,818)	(28,272)
Prior service cost (credit)	34	87	237	262
Actuarial loss (gain)	3,604	3,018	10,643	9,055
Settlement charge				59
Special termination benefit				764
Net periodic benefit cost (credit)	10,133	8,192	28,196	25,400
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	22	60	65
Interest cost	182	216	547	648
Prior service cost (credit)	(436)	(491)	(1,307)	(1,471)
Actuarial loss (gain)	(91)	(125)	(273)	(374)
Special termination benefit				(8)
Net periodic benefit cost (credit)	$ (325)	$ (378)	$ (973)	$ (1,140)

Commitments and Contingencies - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Commitments and Contingencies [Line Items]
Guarantee of affiliate's obligations	$ 25,000,000
Interest-only loan
Commitments and Contingencies [Line Items]
Due from affiliate	$ 6,000,000	$ 6,000,000	$ 6,000,000
Due date	Dec. 31, 2019
Interest-only loan \| London Interbank Offered Rate(LIBOR)
Commitments and Contingencies [Line Items]
Basis spread on variable rate	1.75%

Business Segments - Additional Information (Detail)	9 Months Ended
Business Segments - Additional Information (Detail)	Sep. 30, 2017 Segment
Segment Reporting [Abstract]
Reportable business segments	3

Financial Data for Continuing Operations for Company's Reportable Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 1,087,732	$ 1,103,901	$ 2,995,116	$ 2,869,934
Net sales	1,022,137	1,038,344	2,810,110	2,687,740
Earnings (Loss) from operations	226,964	242,669	516,967	519,541
Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	1,023,827	1,038,752	2,792,606	2,676,979
Net sales	963,611	978,100	2,623,768	2,509,125
Earnings (Loss) from operations	220,639	238,667	517,516	517,957
Operating Segments \| Mid-America Group \| Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	308,472	297,275	788,390	762,297
Net sales	287,078	275,791	734,258	708,151
Earnings (Loss) from operations	106,235	92,170	204,939	187,656
Operating Segments \| Southeast Group \| Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	94,843	83,814	277,474	243,086
Net sales	91,407	80,044	266,556	230,005
Earnings (Loss) from operations	17,882	11,938	42,331	30,579
Operating Segments \| West Group \| Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	620,512	657,663	1,726,742	1,671,596
Net sales	585,126	622,265	1,622,954	1,570,969
Earnings (Loss) from operations	96,522	134,559	270,246	299,722
Operating Segments \| Magnesia Specialties
Segment Reporting Information [Line Items]
Total revenues	63,905	65,149	202,510	192,955
Net sales	58,526	60,244	186,342	178,615
Earnings (Loss) from operations	17,590	20,432	58,589	60,319
Corporate
Segment Reporting Information [Line Items]
Earnings (Loss) from operations	$ (11,265)	$ (16,430)	$ (59,138)	$ (58,735)

Net Sales and Gross Profit by Line of Business (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Product Information [Line Items]
Total revenues	$ 1,087,732	$ 1,103,901	$ 2,995,116	$ 2,869,934
Net sales	1,022,137	1,038,344	2,810,110	2,687,740
Gross profit (loss)	291,678	293,307	712,838	685,988
Corporate
Product Information [Line Items]
Gross profit (loss)	3,446	(3,334)	3,321	(8,908)
Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	1,023,827	1,038,752	2,792,606	2,676,979
Net sales	963,611	978,100	2,623,768	2,509,125
Gross profit (loss)	268,322	273,796	643,668	627,332
Building Materials Business \| Operating Segments \| Interproduct Sales
Product Information [Line Items]
Total revenues	(106,009)	(111,721)	(271,171)	(246,865)
Net sales	(106,009)	(111,721)	(271,171)	(246,866)
Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	63,905	65,149	202,510	192,955
Net sales	58,526	60,244	186,342	178,615
Gross profit (loss)	19,910	22,845	65,849	67,564
Aggregates \| Building Materials Business \| Operating Segments \| Reportable Subsegments
Product Information [Line Items]
Total revenues	647,121	637,995	1,776,292	1,715,457
Net sales	591,195	581,536	1,620,962	1,559,688
Gross profit (loss)	187,947	173,891	440,711	420,972
Cement \| Building Materials Business \| Operating Segments \| Reportable Subsegments
Product Information [Line Items]
Total revenues	91,884	97,287	290,513	287,944
Net sales	88,615	94,744	281,315	279,045
Gross profit (loss)	27,604	36,871	87,962	93,535
Ready Mixed Concrete \| Building Materials Business \| Operating Segments \| Reportable Subsegments
Product Information [Line Items]
Total revenues	240,456	264,050	705,128	666,506
Net sales	240,216	263,747	704,491	665,546
Gross profit (loss)	23,907	32,787	70,562	75,987
Asphalt and Paving
Product Information [Line Items]
Total revenues	150,375	151,141	291,844	253,937
Net sales	149,594	149,794	288,171	251,712
Gross profit (loss)	$ 28,864	$ 30,247	$ 44,433	$ 36,838

Other Operating Expense (Income), Net - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Component Of Other Income And Expense [Line Items]
Nonrecurring repair costs	$ 12,425,000
Other Operating Income, Net
Component Of Other Income And Expense [Line Items]
Gain on sale of real estate		$ 13,500,000
Other Operating Income, Net \| Chief Financial Officer
Component Of Other Income And Expense [Line Items]
Retirement related expense including both cash and stock-based compensation		$ 7,500,000

Components of Change in Other Assets and Liabilities Net (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Other current and noncurrent assets	$ (29,342)	$ (3,997)
Accrued salaries, benefits and payroll taxes	(6,234)	413
Accrued insurance and other taxes	10,230	5,041
Accrued income taxes	16,393	693
Accrued pension, postretirement and postemployment benefits	(5,807)	(21,624)
Other current and noncurrent liabilities	49,244	(1,437)
Change in other assets and liabilities, net	$ 34,484	$ (20,911)

Schedule Of Noncash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Accrued liabilities for purchases of property, plant and equipment	$ 20,339	$ 24,453
Acquisition of assets through capital lease	196	$ 998
Settlement of royalty obligation via asset sale	$ 900

Supplemental Disclosures of Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 49,564	$ 48,813
Cash paid for income taxes	$ 96,643	$ 81,589

Business Combinations - Additional Information (Detail)	3 Months Ended
Business Combinations - Additional Information (Detail)	Sep. 30, 2016 USD ($)	Mar. 31, 2016 T	Jul. 31, 2016
Colorado \| Minimum
Business Combinations [Line Items]
Acquisition of mineral reserves \| T		500,000,000
Central Texas \| Ratliff
Business Combinations [Line Items]
Ownership interest percentage under equity method, prior to acquisition			40.00%
Gain resulting from re-measurement of existing interest to fair value upon closing of transaction \| $	$ 5,863,000

Pending Acquisition of Bluegrass Materials - Additional Information (Detail)	Jun. 26, 2017 USD ($)
Bluegrass Materials Company
Business Combinations [Line Items]
Business acquisition agreed amount to acquire	$ 1,625,000,000