Basic and Diluted Earnings (Loss) Per Common Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net earnings from continuing operations attributable to Martin Marietta Materials, Inc.	$ 117,544	$ 53,812	$ 205,607	$ 91,786
Less: Distributed and undistributed earnings attributable to unvested awards	479	213	897	372
Basic and diluted net earnings available to common shareholders from continuing operations attributable to Martin Marietta Materials, Inc.	117,065	53,599	204,710	91,414
Basic and diluted net loss available to common shareholders from discontinued operations		(69)		(140)
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 117,065	$ 53,530	$ 204,710	$ 91,274
Basic weighted-average common shares outstanding	66,830	67,086	67,203	53,342
Effect of dilutive employee and director awards	278	409	267	217
Diluted weighted-average common shares outstanding	67,108	67,495	67,470	53,559