Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Significant Accounting Policies [Line Items]

Changes in Accumulated Other Comprehensive Earnings Net of Tax

Changes in accumulated other comprehensive earnings, 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, 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	)
	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 loss, 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	)

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, 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	)
	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 loss, 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	)

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, 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
	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
	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
	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

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
	2018			2017			2018			2017			comprehensive earnings
	(Dollars in Thousands)
Pension and postretirement benefit plans
Settlement expense	$	2,692		$	—		$	2,692		$	—
Amortization of:
Prior service credit		(492	)		(402	)		(1,479	)		(1,070	)
Actuarial loss		3,153			3,513			9,463			10,370
		5,353			3,111			10,676			9,300		Other nonoperating income, net
Tax benefit		(1,326	)		(1,193	)		(2,645	)		(3,562	)	Income tax expense
	$	4,027		$	1,918		$	8,031		$	5,738
Unamortized value of terminated    forward starting interest rate swap
Additional interest expense	$	—		$	369		$	458		$	1,089		Interest expense
Tax benefit		—			(147	)		(178	)		(432	)	Income tax expense
	$	—		$	222		$	280		$	657

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,
	2018		2017		2018		2017
	(In Thousands)
Net earnings attributable to Martin Marietta    Materials, Inc.	$	180,221	$	151,546	$	375,621	$	336,159
Less: Distributed and undistributed earnings    attributable to unvested awards		271		399		672		1,000
Basic and diluted net earnings available to common    shareholders attributable to Martin Marietta    Materials, Inc.	$	179,950	$	151,147	$	374,949	$	335,159
Basic weighted-average common shares outstanding		62,932		62,896		62,970		62,940
Effect of dilutive employee and director awards		235		262		254		278
Diluted weighted-average common shares outstanding		63,167		63,158		63,224		63,218

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,
	2018		2017		2018		2017
	(Dollars in Thousands)
Net earnings attributable to Martin Marietta Materials, Inc.	$	180,221	$	151,546	$	375,621	$	336,159
Other comprehensive earnings, net of tax		4,392		2,978		7,613		7,759
Comprehensive earnings attributable to Martin Marietta    Materials, Inc.	$	184,613	$	154,524	$	383,234	$	343,918

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,
	2018		2017			2018		2017
	(Dollars in Thousands)
Net earnings (loss) attributable to noncontrolling interests	$	132	$	(7	)	$	275	$	(72	)
Other comprehensive earnings, net of tax		—		8			1		10
Comprehensive earnings (loss) attributable to    noncontrolling interests	$	132	$	1		$	276	$	(62	)