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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue Recognition [Line Items]
Total	$ 1,279,468	$ 1,202,403	$ 2,218,423	$ 2,004,407
Building Materials Business
Revenue Recognition [Line Items]
Total	1,203,229	1,129,441	2,068,110	1,862,183
Products and Services
Revenue Recognition [Line Items]
Total	1,196,135	1,128,777	2,074,440	1,882,082
Products and Services | Building Materials Business
Revenue Recognition [Line Items]
Total	1,125,756	1,060,620	1,934,887	1,749,057
Freight
Revenue Recognition [Line Items]
Total	83,333	73,626	143,983	122,325
Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	77,473	68,821	133,223	113,126
Operating Segments | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	415,327	350,592	664,140	529,373
Operating Segments | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	137,024	112,963	256,262	193,202
Operating Segments | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	650,878	665,886	1,147,708	1,139,608
Operating Segments | Building Materials Business
Revenue Recognition [Line Items]
Total	1,203,229	1,129,441	2,068,110	1,862,183
Operating Segments | Magnesia Specialties
Revenue Recognition [Line Items]
Total	76,239	72,962	150,313	142,224
Operating Segments | Products and Services | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	382,717	325,578	613,025	493,468
Operating Segments | Products and Services | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	132,036	109,082	247,348	186,646
Operating Segments | Products and Services | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	611,003	625,960	1,074,514	1,068,943
Operating Segments | Products and Services | Magnesia Specialties
Revenue Recognition [Line Items]
Total	70,379	68,157	139,553	133,025
Operating Segments | Freight | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	32,610	25,014	51,115	35,905
Operating Segments | Freight | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	4,988	3,881	8,914	6,556
Operating Segments | Freight | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	39,875	39,926	73,194	70,665
Operating Segments | Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	77,473	68,821	133,223	113,126
Operating Segments | Freight | Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 5,860	$ 4,805	$ 10,760	$ 9,199