Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2019

Significant Accounting Policies [Line Items]

Changes in Accumulated Other Comprehensive Loss Net of Tax

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

	(Dollars in Thousands)
	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Accumulated Other Comprehensive Loss
	Three Months Ended September 30, 2019
Balance at beginning of period	$	(136,021	)	$	(1,313	)	$	—		$	(137,334	)
Amounts reclassified from accumulated    other comprehensive loss, net of tax		2,726			(157	)		—			2,569
Balance at end of period	$	(133,295	)	$	(1,470	)	$	—		$	(134,765	)
	Three Months Ended September 30, 2018
Balance at beginning of period	$	(124,798	)	$	(1,085	)	$	—		$	(125,883	)
Other comprehensive earnings before    reclassifications, net of tax		—			365			—			365
Amounts reclassified from accumulated    other comprehensive loss, net of tax		4,027			—			—			4,027
Other comprehensive earnings, net of tax		4,027			365			—			4,392
Balance at end of period	$	(120,771	)	$	(720	)	$	—		$	(121,491	)
	Nine Months Ended September 30, 2019
Balance at beginning of period	$	(141,505	)	$	(2,074	)	$	—		$	(143,579	)
Amounts reclassified from accumulated    other comprehensive loss, net of tax		8,210			604			—			8,814
Balance at end of period	$	(133,295	)	$	(1,470	)	$	—		$	(134,765	)
	Nine Months Ended September 30, 2018
Balance at beginning of period	$	(128,802	)	$	(22	)	$	(280	)	$	(129,104	)
Other comprehensive loss before    reclassifications, net of tax		—			(698	)		—			(698	)
Amounts reclassified from accumulated    other comprehensive loss, net of tax		8,031			—			280			8,311
Other comprehensive earnings (loss), net of tax		8,031			(698	)		280			7,613
Balance at end of period	$	(120,771	)	$	(720	)	$	—		$	(121,491	)

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, 2019
Balance at beginning of period	$	82,417		$	—		$	82,417
Tax effect of other comprehensive earnings		(899	)		—			(899	)
Balance at end of period	$	81,518		$	—		$	81,518
	Three Months Ended September 30, 2018
Balance at beginning of period	$	78,619		$	—		$	78,619
Tax effect of other comprehensive earnings		(1,326	)		—			(1,326	)
Balance at end of period	$	77,293		$	—		$	77,293
	Nine Months Ended September 30, 2019
Balance at beginning of period	$	84,207		$	—		$	84,207
Tax effect of other comprehensive earnings		(2,689	)		—			(2,689	)
Balance at end of period	$	81,518		$	—		$	81,518
	Nine Months Ended September 30, 2018
Balance at beginning of period	$	79,938		$	178		$	80,116
Tax effect of other comprehensive earnings		(2,645	)		(178	)		(2,823	)
Balance at end of period	$	77,293		$	—		$	77,293

Reclassification Out of Accumulated Other Comprehensive Loss

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
	2019			2018			2019			2018			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit    plans
Settlement expense	$	—		$	2,692		$	—		$	2,692
Amortization of:
Prior service credit		(188	)		(492	)		(566	)		(1,479	)
Actuarial loss		3,813			3,153			11,465			9,463
		3,625			5,353			10,899			10,676		Other nonoperating (income) and expense, net
Tax benefit		(899	)		(1,326	)		(2,689	)		(2,645	)	Income tax expense
	$	2,726		$	4,027		$	8,210		$	8,031
Unamortized value of terminated    forward starting interest rate    swap
Additional interest expense	$	—		$	—		$	—		$	458		Interest expense
Tax benefit		—			—			—			(178	)	Income tax expense
	$	—		$	—		$	—		$	280

Basic and Diluted Earnings Per Common Share

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
	(In Thousands)
Net earnings attributable to Martin Marietta    Materials, Inc.	$	248,573	$	180,221	$	480,901	$	375,621
Less: Distributed and undistributed earnings    attributable to unvested awards		345		271		886		672
Basic and diluted net earnings available to common    shareholders attributable to Martin Marietta    Materials, Inc.	$	248,228	$	179,950	$	480,015	$	374,949
Basic weighted-average common shares outstanding		62,510		62,932		62,552		62,970
Effect of dilutive employee and director awards		169		235		173		254
Diluted weighted-average common shares outstanding		62,679		63,167		62,725		63,224

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,
	2019		2018		2019		2018
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	248,573	$	180,221	$	480,901	$	375,621
Other comprehensive earnings, net of tax		2,569		4,392		8,814		7,613
Comprehensive earnings attributable to Martin Marietta    Materials, Inc.	$	251,142	$	184,613	$	489,715	$	383,234

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, are as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
	(Dollars in Thousands)
Net earnings attributable to noncontrolling interests	$	49	$	132	$	17	$	275
Other comprehensive earnings, net of tax		—		—		—		1
Comprehensive earnings attributable to    noncontrolling interests	$	49	$	132	$	17	$	276