Net Sales and Gross Profit by Line of Business (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Product Information [Line Items]
Net Sales	$ 850,249	$ 601,937	$ 1,482,124	$ 981,615
Gross profit (loss)	200,153	135,602	274,414	161,438
Aggregates Business
Product Information [Line Items]
Net Sales	689,387	540,017	1,165,943	862,346
Gross profit (loss)	154,504	111,744	193,230	119,332
Operating Segments | Cement
Product Information [Line Items]
Net Sales	100,405		196,970
Gross profit (loss)	30,414		49,400
Operating Segments | Magnesia Specialties
Product Information [Line Items]
Net Sales	60,457	61,920	119,211	119,269
Gross profit (loss)	21,224	23,394	41,402	42,149
Corporate
Product Information [Line Items]
Gross profit (loss)	(5,989)	464	(9,618)	(43)
Aggregates
Product Information [Line Items]
Net Sales	481,616	421,974	813,830	685,858
Gross profit (loss)	137,272	100,142	178,690	110,194
Asphalt
Product Information [Line Items]
Net Sales	18,896	22,627	28,541	33,125
Gross profit (loss)	4,314	4,869	2,851	3,443
Ready Mixed Concrete
Product Information [Line Items]
Net Sales	149,750	52,379	277,323	90,388
Gross profit (loss)	9,341	6,982	11,424	9,926
Road Paving
Product Information [Line Items]
Net Sales	39,125	43,037	46,249	52,975
Gross profit (loss)	$ 3,577	$ (249)	$ 265	$ (4,231)