Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 159,479	$ 117,544	$ 326,526	$ 205,607
Other comprehensive earnings (loss), net of tax	1,557	72	1,111	(6,583)
Earnings attributable to Martin Marietta Materials, Inc.	$ 161,036	$ 117,616	$ 327,637	$ 199,024