Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net earnings from continuing operations attributable to Martin Marietta Materials, Inc.	$ 122,052	$ 81,938	$ 167,047	$ 88,065
Less: Distributed and undistributed earnings attributable to unvested awards	519	(876)	730	403
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 121,533	$ 82,814	$ 166,317	$ 87,662
Basic weighted-average common shares outstanding	63,532	67,373	63,845	67,392
Effect of dilutive employee and director awards	270	260	246	262
Diluted weighted-average common shares outstanding	63,802	67,633	64,091	67,654