Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 159,479	$ 117,544	$ 326,526	$ 205,607
Less: Distributed and undistributed earnings attributable to unvested awards	637	479	1,388	897
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 158,842	$ 117,065	$ 325,138	$ 204,710
Basic weighted-average common shares outstanding	63,452	66,830	63,713	67,203
Effect of dilutive employee and director awards	271	278	254	267
Diluted weighted-average common shares outstanding	63,723	67,108	63,967	67,470