Business Combinations, Dispositions and Related Transactions - Schedule of Consolidated Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2018
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total	$ 4.3	$ 4.3	$ 34.1
Waste Management
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net sales:			4.6
Operating loss			(0.4)
Interest expense, net			(0.3)
Loss before taxes			(0.7)
Income tax benefit			(0.1)
Net loss			(0.6)
Pre-tax gain on disposal	$ 4.9		58.4
Income tax expense			23.7
After-tax gain on disposal			34.7
Total			34.1
Net cash provided by operating activities			2.3
Net cash used in investing activities			$ (0.1)