Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Federal statutory rate	21.00%	21.00%	35.00%
Valuation allowance	$ 23.0	$ 15.4
Income tax benefit	20.4	(4.6)	$ 41.2
Write off of 2012 Veolia acquisition related indemnification receivable	3.9	0.0	0.0
Interest expense related to unrecognized tax benefits in tax expense	0.0	0.4	$ 0.5
Accrued interest	0.0	3.2
Accrued penalties	0.0	0.6
Tax Period Prior to November 30, 2005
Income Tax [Line Items]
Operating loss carryforwards	30.8
Estimated annual limitation of NOLs	4.2
HWStar Waste Holdings, Corp. and subsidiaries
Income Tax [Line Items]
Operating loss carryforwards	71.9
Federal
Income Tax [Line Items]
Operating loss carryforwards	406.3	$ 349.1
Operating loss carryforwards, subject to expiration	358.9
Operating loss carryforwards, not subject to expiration	$ 47.4