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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue Recognition [Line Items]
Total	$ 1,420,246	$ 1,219,640	$ 3,638,668	$ 3,224,047
Building Materials Business
Revenue Recognition [Line Items]
Total	1,355,369	1,146,117	3,423,478	3,008,300
Products and Services
Revenue Recognition [Line Items]
Total	1,323,160	1,142,218	3,397,599	3,024,300
Products and Services | Building Materials Business
Revenue Recognition [Line Items]
Total	1,263,826	1,073,853	3,198,713	2,822,910
Freight
Revenue Recognition [Line Items]
Total	97,086	77,422	241,069	199,747
Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	91,543	72,264	224,765	185,390
Operating Segments | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	448,758	377,005	1,112,897	906,377
Operating Segments | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	134,138	125,547	390,399	318,749
Operating Segments | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	772,473	643,565	1,920,182	1,783,174
Operating Segments | Building Materials Business
Revenue Recognition [Line Items]
Total	1,355,369	1,146,117	3,423,478	3,008,300
Operating Segments | Magnesia Specialties
Revenue Recognition [Line Items]
Total	64,877	73,523	215,190	215,747
Operating Segments | Products and Services | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	411,045	348,429	1,024,069	841,897
Operating Segments | Products and Services | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	129,619	121,661	376,967	308,306
Operating Segments | Products and Services | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	723,162	603,763	1,797,677	1,672,707
Operating Segments | Products and Services | Magnesia Specialties
Revenue Recognition [Line Items]
Total	59,334	68,365	198,886	201,390
Operating Segments | Freight | Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	37,713	28,576	88,828	64,480
Operating Segments | Freight | Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	4,519	3,886	13,432	10,443
Operating Segments | Freight | Building Materials Business West Group
Revenue Recognition [Line Items]
Total	49,311	39,802	122,505	110,467
Operating Segments | Freight | Building Materials Business
Revenue Recognition [Line Items]
Total	91,543	72,264	224,765	185,390
Operating Segments | Freight | Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 5,543	$ 5,158	$ 16,304	$ 14,357