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Asset Impairments and Unusual Items - Details (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 30, 2020
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments	$ 7.0	$ 61.0			$ 68.0	$ 42.0	$ 38.0
Goodwill impairment charges						27.0
Solid waste operations impairment						15.0
(Gain) loss from divestitures, asset impairments and unusual items, net					35.0	42.0	(58.0)
Gain (loss) on sale of assets					33.0		96.0
Payments made for contingent consideration						(6.0)
Investment impairment				$ 52.0		52.0
Disposed of by Sale, Not Discontinued Operations [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Gain (loss) on sale of assets					33.0		96.0
Advanced Disposal [Member] \| Disposed of by Sale, Not Discontinued Operations [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Gain (loss) on sale of assets					33.0
Divestiture consideration								$ 856.0
Refined Coal Facility [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Equity method investments impairment charges			$ 7.0		7.0
Energy and Environmental Services [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Goodwill impairment charges						17.0
Lamp Tracker Reporting Unit [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments							8.0
Goodwill impairment charges						10.0
Landfill [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments					20.0		30.0
Landfills and Oil Field Waste Injection Facility [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments		41.0
Asset fair value		8.0
Energy Services Assets [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset fair value		239.0
Tier 1 [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments		41.0
Gain (loss) on sale of assets							52.0
Other [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments					$ 16.0
Goodwill impairment charges						$ 27.0
Gain (loss) on sale of assets							$ 44.0
Carrying Value [Member] \| Landfill [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments		12.0
Expected Timing [Member] \| Landfill [Member]
Income Expense From Divestitures Asset Impairments And Unusual Items [Line Items]
Asset impairments		$ 8.0