Revenue Recognition - Schedule of Company's Total Revenues by Category for each Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue Recognition [Line Items]
Total	$ 1,219,640	$ 1,087,732	$ 3,224,047	$ 2,995,116
Building Materials Business
Revenue Recognition [Line Items]
Total	1,146,117	1,023,827	3,008,300	2,792,606
Products and Services
Revenue Recognition [Line Items]
Total	1,142,218	1,022,487	3,024,300	2,811,646
Products and Services | Building Materials Business
Revenue Recognition [Line Items]
Total	1,073,853	962,598	2,822,910	2,621,728
Freight
Revenue Recognition [Line Items]
Total	77,422	65,245	199,747	183,470
Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	72,264	61,229	185,390	170,878
Operating Segments | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	377,005	308,472	906,377	788,390
Operating Segments | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	125,547	94,843	318,749	277,474
Operating Segments | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	643,565	620,512	1,783,174	1,726,742
Operating Segments | Building Materials Business
Revenue Recognition [Line Items]
Total	1,146,117	1,023,827	3,008,300	2,792,606
Operating Segments | Magnesia Specialties
Revenue Recognition [Line Items]
Total	73,523	63,905	215,747	202,510
Operating Segments | Products and Services | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	348,429	287,085	841,897	734,406
Operating Segments | Products and Services | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	121,661	91,427	308,306	266,690
Operating Segments | Products and Services | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	603,763	584,086	1,672,707	1,620,632
Operating Segments | Products and Services | Magnesia Specialties
Revenue Recognition [Line Items]
Total	68,365	59,889	201,390	189,918
Operating Segments | Freight | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	28,576	21,387	64,480	53,984
Operating Segments | Freight | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	3,886	3,416	10,443	10,784
Operating Segments | Freight | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	39,802	36,426	110,467	106,110
Operating Segments | Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	72,264	61,229	185,390	170,878
Operating Segments | Freight | Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 5,158	$ 4,016	$ 14,357	$ 12,592