Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 122,052	$ 81,938	$ 167,047	$ 88,065
Other comprehensive loss, net of tax	(2,235)	(6,091)	(446)	(6,655)
Earnings attributable to Martin Marietta Materials, Inc.	$ 119,817	$ 75,847	$ 166,601	$ 81,410