Basic and Diluted Earnings (Loss) Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net earnings from continuing operations attributable to Martin Marietta Materials, Inc.	$ 81,938	$ 59,577	$ 88,065	$ 37,974
Less: Distributed and undistributed earnings attributable to unvested awards	876	(246)	(403)	(154)
Basic and diluted net earnings available to common shareholders from continuing operations attributable to Martin Marietta Materials, Inc.	82,814	59,331	87,662	37,820
Basic and diluted net loss available to common shareholders from discontinued operations		(56)		(70)
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 82,814	$ 59,275	$ 87,662	$ 37,750
Basic weighted-average common shares outstanding	67,373	46,395	67,392	46,355
Effect of dilutive employee and director awards	260	134	262	122
Diluted weighted-average common shares outstanding	67,633	46,529	67,654	46,477