Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Estimated Service Lives for Property Plant and Equipment

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

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

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

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

	Pension and Postretirement Benefit Plans			Foreign Currency			Unamortized Value of Terminated Forward Starting Interest Rate Swap			Total
years ended December 31 (in millions)	2019
Accumulated other comprehensive loss at beginning of period	$	(141.5	)	$	(2.1	)	$	—		$	(143.6	)
Other comprehensive (loss) earnings before reclassifications, net of tax		(14.5	)		1.2			—			(13.3	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		11.1			—			—			11.1
Other comprehensive (loss) earnings, net of tax		(3.4	)		1.2			—			(2.2	)
Accumulated other comprehensive loss at end of period	$	(144.9	)	$	(0.9	)	$	—		$	(145.8	)
Cumulative noncurrent deferred tax assets at end of period	$	85.2		$	—		$	—		$	85.2

	2018
Accumulated other comprehensive loss at beginning of period	$	(128.8	)	$	—		$	(0.3	)	$	(129.1	)
Other comprehensive loss before reclassifications, net of tax		(22.9	)		(2.1	)		—			(25.0	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		10.2			—			0.3			10.5
Other comprehensive (loss) earnings, net of tax		(12.7	)		(2.1	)		0.3			(14.5	)
Accumulated other comprehensive loss at end of period	$	(141.5	)	$	(2.1	)	$	—		$	(143.6	)
Cumulative noncurrent deferred tax assets at end of period	$	84.2		$	—		$	—		$	84.2

	2017
Accumulated other comprehensive loss at beginning of period	$	(128.4	)	$	(1.2	)	$	(1.1	)	$	(130.7	)
Other comprehensive (loss) earnings before reclassifications, net of tax		(8.1	)		1.2			—			(6.9	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		7.7			—			0.8			8.5
Other comprehensive (loss) earnings, net of tax		(0.4	)		1.2			0.8			1.6
Accumulated other comprehensive loss at end of period	$	(128.8	)	$	—		$	(0.3	)	$	(129.1	)
Cumulative noncurrent deferred tax assets at end of period	$	79.9		$	—		$	0.2		$	80.1

Reclassification Out of Accumulated Other Comprehensive Loss

Reclassifications out of accumulated other comprehensive loss are as follows:

years ended December 31 (in millions)	2019			2018			2017			Affected line items in the consolidated statements of earnings
Pension and postretirement benefit plans:
Settlement charge	$	—		$	2.9		$	—
Amortization of:
Prior service credit		(0.8	)		(2.0	)		(1.4	)
Actuarial loss		15.5			12.7			13.8
		14.7			13.6			12.4		Other nonoperating expenses and (income), net
Tax effect		(3.6	)		(3.4	)		(4.7	)	Income tax expense (benefit)
Total	$	11.1		$	10.2		$	7.7
Unamortized value of terminated forward starting interest rate swap:
Additional interest expense	$	—		$	0.5		$	1.4		Interest expense
Tax effect		—			(0.2	)		(0.6	)	Income tax expense (benefit)
Total	$	—		$	0.3		$	0.8

Basic and Diluted Earnings Per Common Share

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

years ended December 31 (in millions)	2019		2018		2017
Net earnings attributable to Martin Marietta	$	611.9	$	470.0	$	713.3
Less: Distributed and undistributed earnings attributable to unvested participating securities		0.9		0.8		2.0
Basic and diluted net earnings attributable to common shareholders attributable to Martin Marietta	$	611.0	$	469.2	$	711.3

Basic weighted-average common shares outstanding		62.5		62.9		62.9
Effect of dilutive employee and director awards		0.2		0.2		0.3
Diluted weighted-average common shares outstanding		62.7		63.1		63.2