Segment Information- Financial Information for Operations (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Net Sales, EBIT, Assets continuing operations by reportable segment
Number of reportable segments | segment									2
Revenues	$ 1,127.5	$ 1,259.8	$ 1,307.0	$ 892.6	$ 1,149.9	$ 1,497.0	$ 1,562.3	$ 1,240.2	$ 4,586.9	$ 5,449.4	$ 3,836.7
Operating income	$ 253.6	$ 299.9	$ 308.6	$ 120.7	$ 209.5	$ 324.0	$ 396.1	$ 275.2	982.8	1,204.8	573.4
Depreciation and Amortization									151.1	158.6	119.7
Capital Expenditures									$ 110.8	$ 158.8	$ 105.5
Customer | Net sales | Beacon Roofing Supply, Inc
Net Sales, EBIT, Assets continuing operations by reportable segment
Concentration risk (as a percent)									16.40%	13.20%	15.30%
Customer | Net sales | ABC Supply Co.
Net Sales, EBIT, Assets continuing operations by reportable segment
Concentration risk (as a percent)									15.30%	13.20%	15.60%
Operating Segments
Net Sales, EBIT, Assets continuing operations by reportable segment
Revenues									$ 4,586.9	$ 5,449.4	$ 3,836.7
Operating income									1,101.8	1,303.6	684.3
Depreciation and Amortization									145.1	152.7	114.0
Capital Expenditures									110.5	156.7	103.1
Corporate and unallocated
Net Sales, EBIT, Assets continuing operations by reportable segment
Revenues									0.0	0.0	0.0
Operating income									(119.0)	(98.8)	(110.9)
Depreciation and Amortization									6.0	5.9	5.7
Capital Expenditures									0.3	2.1	2.4
CCM
Net Sales, EBIT, Assets continuing operations by reportable segment
Revenues									3,253.4	3,885.2	2,846.2
CCM | Operating Segments
Net Sales, EBIT, Assets continuing operations by reportable segment
Revenues									3,253.4	3,885.2	2,846.2
Operating income									913.9	1,175.0	619.9
Depreciation and Amortization									57.0	55.6	52.7
Capital Expenditures									84.5	135.1	83.8
CWT
Net Sales, EBIT, Assets continuing operations by reportable segment
Revenues									1,333.5	1,564.2	990.5
CWT | Operating Segments
Net Sales, EBIT, Assets continuing operations by reportable segment
Revenues									1,333.5	1,564.2	990.5
Operating income									187.9	128.6	64.4
Depreciation and Amortization									88.1	97.1	61.3
Capital Expenditures									$ 26.0	$ 21.6	$ 19.3