Basic and Diluted Earnings Per Common Share (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Earnings Per Share, Basic and Diluted, by Common Class
Net earnings from continuing operations attributable to Martin Marietta Materials, Inc.	$ 72,107	$ 63,241	$ 85,758	$ 63,907
Less: Distributed and undistributed earnings attributable to unvested awards	265	336	374	386
Basic and diluted net earnings available to common shareholders from continuing operations attributable to Martin Marietta Materials, Inc.	71,842	62,905	85,384	63,521
Basic and diluted net loss available to common shareholders from discontinued operations	(271)	(319)	(454)	(967)
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 71,571	$ 62,586	$ 84,930	$ 62,554
Basic weighted-average common shares outstanding	46,244	45,860	46,134	45,792
Effect of dilutive employee and director awards	105	132	127	137
Diluted weighted-average common shares outstanding	46,349	45,992	46,261	45,929