Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 151,546	$ 159,479	$ 336,159	$ 326,526
Other comprehensive earnings, net of tax	2,978	1,557	7,759	1,111
Earnings attributable to Martin Marietta Materials, Inc.	$ 154,524	$ 161,036	$ 343,918	$ 327,637