Revenue Recognition - Schedule of Company's Total Revenues by Category for each Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue Recognition [Line Items]
Total	$ 1,202,403	$ 1,063,524	$ 2,004,407	$ 1,907,383
Building Materials Business
Revenue Recognition [Line Items]
Total	1,129,441	993,495	1,862,183	1,768,778
Products and Services
Revenue Recognition [Line Items]
Total	1,128,777	996,843	1,882,082	1,789,159
Products and Services | Building Materials Business
Revenue Recognition [Line Items]
Total	1,060,620	931,115	1,749,057	1,659,130
Freight
Revenue Recognition [Line Items]
Total	73,626	66,681	122,325	118,224
Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	68,821	62,380	113,126	109,648
Operating Segments | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	350,592	290,898	529,373	479,918
Operating Segments | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	112,963	92,348	193,202	182,630
Operating Segments | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	665,886	610,249	1,139,608	1,106,230
Operating Segments | Building Materials Business
Revenue Recognition [Line Items]
Total	1,129,441	993,495	1,862,183	1,768,778
Operating Segments | Magnesia Specialties
Revenue Recognition [Line Items]
Total	72,962	70,029	142,224	138,605
Operating Segments | Products and Services | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	325,578	269,914	493,468	447,321
Operating Segments | Products and Services | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	109,082	88,538	186,646	175,264
Operating Segments | Products and Services | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	625,960	572,663	1,068,943	1,036,545
Operating Segments | Products and Services | Magnesia Specialties
Revenue Recognition [Line Items]
Total	68,157	65,728	133,025	130,029
Operating Segments | Freight | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	25,014	20,984	35,905	32,597
Operating Segments | Freight | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	3,881	3,810	6,556	7,366
Operating Segments | Freight | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	39,926	37,586	70,665	69,685
Operating Segments | Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	68,821	62,380	113,126	109,648
Operating Segments | Freight | Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 4,805	$ 4,301	$ 9,199	$ 8,576