ACQUISITIONS - Narrative (Details) - USD ($) $ in Millions			1 Months Ended	3 Months Ended
	Mar. 10, 2021	Jan. 03, 2020	Mar. 31, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Business Acquisition [Line Items]
Contingent consideration related to acquisition			$ 20.6	$ 20.6		$ 0.0
Consolidated net revenue				160.4	$ 167.3
Operating expense				(67.8)	(61.7)
Goodwill			181.3	181.3		$ 136.1
Flexiti
Business Acquisition [Line Items]
Equity interests acquired	100.00%
Payments to acquire businesses, gross	$ 86.5
Debt costs in conjunction with the acquisition	6.3
Contingent consideration related to acquisition	20.6
Consolidated net revenue			0.8
Operating expense			3.5
Goodwill	44.9
Business combination, consideration transferred, equity interests issued and issuable	8.1
Business combination, consideration transferred, equity interests issued relates to RSU contingent consideration	$ 4.0
Business acquisition, service period term	2 years
Business acquisition, incurred costs related to this acquisition			$ 3.2	3.2
Payments to acquire businesses, net of cash acquired				91.2	0.0
Flexiti | Minimum
Business Acquisition [Line Items]
Contingent consideration related to acquisition	$ 0.0
Flexiti | Maximum
Business Acquisition [Line Items]
Contingent consideration related to acquisition	$ 32.8
Ad Astra
Business Acquisition [Line Items]
Equity interests acquired		100.00%
Operating expense				2.6
Goodwill		$ 14.8
Payments to acquire businesses, net of cash acquired		14.4		$ 0.0	$ 14.4
Insurance amount deductible		$ 15.4