Segments - Financial Data for Continuing Operations for Company's Reportable Segments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 4,729.9	$ 4,739.1	$ 4,244.3
Gross profit	1,252.8	1,179.0	966.6
Selling, general and administrative expenses	305.9	302.7	280.6
Earnings (Loss) from operations	1,005.4	884.9	690.7
Assets employed	10,580.8	10,131.6	9,551.4
Depreciation, depletion and amortization	393.5	371.5	344.0
Total property additions, including the impact of acquisitions	387.2	387.6	1,925.6
Property additions through acquisitions	20.0		1,543.2
Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	4,487.2	4,467.8	3,956.6
Gross profit	1,159.8	1,080.6	860.3
Selling, general and administrative expenses	234.9	201.0	182.1
Earnings (Loss) from operations	993.4	894.2	690.8
Assets employed	9,698.0	9,642.5	9,077.6
Depreciation, depletion and amortization	364.5	341.3	315.7
Total property additions, including the impact of acquisitions	356.9	355.6	1,908.3
Property additions through acquisitions	20.0		1,543.2
Operating Segments | Building Materials Business East Group
Segment Reporting Information [Line Items]
Total revenues	1,949.1	1,949.0	1,643.1
Gross profit	619.4	605.7	442.9
Selling, general and administrative expenses	99.2	84.7	74.5
Earnings (Loss) from operations	522.1	527.3	393.1
Assets employed	4,342.5	4,320.6	4,086.8
Depreciation, depletion and amortization	167.9	158.0	134.8
Total property additions, including the impact of acquisitions	159.0	172.9	1,760.2
Property additions through acquisitions			1,541.8
Operating Segments | Building Materials Business West Group
Segment Reporting Information [Line Items]
Total revenues	2,538.1	2,518.8	2,313.5
Gross profit	540.4	474.9	417.4
Selling, general and administrative expenses	135.7	116.3	107.6
Earnings (Loss) from operations	471.3	366.9	297.7
Assets employed	5,355.5	5,321.9	4,990.8
Depreciation, depletion and amortization	196.6	183.3	180.9
Total property additions, including the impact of acquisitions	197.9	182.7	148.1
Property additions through acquisitions	20.0		1.4
Operating Segments | Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	4,487.2	4,467.8	3,956.6
Gross profit	1,159.8	1,080.6	860.3
Operating Segments | Magnesia Specialties
Segment Reporting Information [Line Items]
Total revenues	242.7	271.3	287.7
Gross profit	85.5	95.4	98.7
Selling, general and administrative expenses	14.1	11.3	10.0
Earnings (Loss) from operations	70.7	83.6	88.1
Assets employed	167.9	176.2	156.1
Depreciation, depletion and amortization	11.5	10.2	10.4
Total property additions, including the impact of acquisitions	13.5	20.0	12.5
Corporate
Segment Reporting Information [Line Items]
Gross profit	7.5	3.0	7.6
Selling, general and administrative expenses	56.9	90.4	88.5
Earnings (Loss) from operations	(58.7)	(92.9)	(88.2)
Assets employed	714.9	312.9	317.7
Depreciation, depletion and amortization	17.5	20.0	17.9
Total property additions, including the impact of acquisitions	$ 16.8	$ 12.0	$ 4.8