SEGMENT REPORTING - Summary of Financial Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Consolidated revenue	$ 196.6	$ 280.8
Consolidated net revenue	160.4	167.3
Consolidated gross margin	101.9	99.7
Consolidated operating income	34.1	38.0
Consolidated expenditures for long-lived assets	3.2	4.9
Total gross loans receivable	731.0		$ 553.7
U.S.
Segment Reporting Information [Line Items]
Consolidated revenue	136.5	221.8
Consolidated net revenue	110.4	135.7
Consolidated gross margin	71.1	87.5
Consolidated operating income	14.7	33.5
Consolidated expenditures for long-lived assets	2.7	4.3
Total gross loans receivable	185.8		223.4
Canada Direct Lending
Segment Reporting Information [Line Items]
Consolidated revenue	58.5	59.0
Consolidated net revenue	49.2	31.6
Consolidated gross margin	30.2	12.2
Consolidated operating income	22.2	4.5
Consolidated expenditures for long-lived assets	0.1	0.6
Total gross loans receivable	343.7		330.3
Canada POS Lending
Segment Reporting Information [Line Items]
Consolidated revenue	1.6	0.0
Consolidated net revenue	0.8	0.0
Consolidated gross margin	0.6	0.0
Consolidated operating income	(2.8)	0.0
Consolidated expenditures for long-lived assets	0.4	$ 0.0
Total gross loans receivable	$ 201.5		$ 0.0