Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 81,938	$ 59,521	$ 88,065	$ 37,904
Other comprehensive (loss) earnings, net of tax	(6,091)	603	(6,655)	1,973
Earnings attributable to Martin Marietta Materials, Inc.	$ 75,847	$ 60,124	$ 81,410	$ 39,877