Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 142,279	$ 122,052	$ 184,613	$ 167,047
Other comprehensive earnings (loss), net of tax	2,519	(2,235)	4,781	(446)
Earnings attributable to Martin Marietta Materials, Inc.	$ 144,798	$ 119,817	$ 189,394	$ 166,601