Basic and Diluted Earnings Per Common Share (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule of Earnings Per Share, Basic and Diluted, by Common Class
Net earnings from continuing operations attributable to Martin Marietta Materials, Inc.	$ 59,577	$ 41,203	$ 37,974	$ 13,651
Less: Distributed and undistributed earnings attributable to unvested awards	246	197	154	182
Basic and diluted net earnings available to common shareholders from continuing operations attributable to Martin Marietta Materials, Inc.	59,331	41,006	37,820	13,469
Basic and diluted net (loss) earnings available to common shareholders from discontinued operations	(56)	105	(70)	(183)
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 59,275	$ 41,111	$ 37,750	$ 13,286
Basic weighted-average common shares outstanding	46,395	46,129	46,355	46,079
Effect of dilutive employee and director awards	134	131	122	138
Diluted weighted-average common shares outstanding	46,529	46,260	46,477	46,217