FAIR VALUE MEASUREMENTS - Investment in Katapult (Details) - Equity Method Investment - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 27.4	$ 23.9	$ 9.2	$ 8.5	$ 10.1
Equity method income (loss)	0.5	1.9	3.5	0.7	(1.6)
Accounting policy change for certain securities from equity method investment to measurement alternative			0.0
Purchases of common stock warrants and preferred shares		1.6	11.2
Ending balance	27.9	27.4	23.9	9.2	8.5
Fair Value, Measurements, Nonrecurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	7.7	4.2	9.2	8.5	10.1
Equity method income (loss)	0.5	1.9	3.5	0.7	(1.6)
Accounting policy change for certain securities from equity method investment to measurement alternative			(12.5)
Purchases of common stock warrants and preferred shares		1.6	4.0
Ending balance	8.2	7.7	4.2	9.2	$ 8.5
Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	19.7	19.7	0.0
Equity method income (loss)	0.0	0.0	0.0
Accounting policy change for certain securities from equity method investment to measurement alternative			12.5
Purchases of common stock warrants and preferred shares		0.0	7.2
Ending balance	$ 19.7	$ 19.7	$ 19.7	$ 0.0