Business Combinations, Dispositions and Related Transactions - Schedule of Consolidated Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total	$ (4.6)	$ 0.7	$ 0.4	$ 37.6	$ (1.0)	$ 1.7	$ (108.2)	$ (1.7)	$ 34.1	$ (109.2)	$ (24.0)
Waste Management
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net sales									4.6	75.4	47.4
Operating loss									(0.4)	(167.1)	(26.2)
Termination fee										4.0
Other income (expense), net										(8.4)	(5.3)
Interest expense, net									(0.3)	(4.8)	(5.1)
Loss before taxes									(0.7)	(176.3)	(36.6)
Income tax benefit									(0.1)	(67.1)	(12.6)
Net loss									(0.6)	(109.2)	(24.0)
Pre-tax gain from disposal of discontinued operations									58.4
Income tax expense									23.7
After-tax gain on disposal									34.7
Total									34.1	(109.2)	(24.0)
Net cash provided by (used in) operating activities									2.3	18.1	(10.7)
Net cash provided by (used in) investing activities									$ (0.1)	$ (3.4)	$ (2.7)