DEBT - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Aug. 31, 2018
Debt Instrument [Line Items]
Debt	$ 1,000.2	$ 819.7
Revolving Credit Facility | Non-Recourse Flexiti SPE Facility
Debt Instrument [Line Items]
Debt	$ 178.4	$ 0.0
Senior Notes | 8.25% Senior Secured Notes
Debt Instrument [Line Items]
Stated interest rate	8.25%	8.25%	8.25%
Debt	$ 680.5	$ 680.0
Line of Credit | Non-Recourse U.S. SPV facility
Debt Instrument [Line Items]
Debt	44.0
Line of Credit | Revolving Credit Facility | Non-Recourse U.S. SPV facility
Debt Instrument [Line Items]
Debt	44.0	43.6
Line of Credit | Revolving Credit Facility | Non-Recourse Canada SPV Facility
Debt Instrument [Line Items]
Debt	97.3	$ 96.1
Line of Credit | Revolving Credit Facility | Non-Recourse Flexiti SPE Facility
Debt Instrument [Line Items]
Debt	$ 178.4