ACQUISITIONS AND DIVESTITURES - Narrative (Details) $ in Thousands						3 Months Ended				9 Months Ended		12 Months Ended	15 Months Ended	21 Months Ended
	Sep. 30, 2023 USD ($)	Aug. 31, 2023 USD ($)	Jul. 13, 2022 USD ($)	Jul. 08, 2022 USD ($)	Dec. 27, 2021 USD ($) branch state	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2021	Jul. 31, 2021
Business Acquisition [Line Items]
Goodwill	$ 276,269					$ 276,269	$ 276,269			$ 276,269		$ 276,269	$ 276,269	$ 276,269
Payments to acquire businesses, net of cash acquired										0	$ 131,012
Interest and fee revenue									$ 7,700			$ 0
Total proceeds										(2,027)	288,980
Gain (loss) on sale of business						0		$ 68,443		(2,027)	68,443
Pre-tax net income						$ (32,591)		42,826		$ (115,140)	34,207
7.5% Senior Secured Notes | Senior Notes
Business Acquisition [Line Items]
Stated interest rate (as a percent)	7.50%					7.50%	7.50%			7.50%		7.50%	7.50%	7.50%	7.50%	7.50%
U.S. Legacy Direct Lending Business
Business Acquisition [Line Items]
Pre-tax net income								$ 3,600			$ 60,700
Discontinued Operations, Disposed of by Sale | U.S. Legacy Direct Lending Business
Business Acquisition [Line Items]
Cash received at close of divestiture of business				$ 314,200
Total proceeds	$ 347,180			349,207
Additional proceeds from divestiture of businesses				35,000
Gain (loss) on sale of business	66,417			$ 68,444		$ 0				$ (2,000)		$ 68,400
Reduction of gain on divestiture						0							$ (2,027)
Discontinued Operations, Disposed of by Sale | Flexiti
Business Acquisition [Line Items]
Base consideration received on sale		$ 40,600
Cash received at close of divestiture of business		$ 28,600
Gain (loss) on sale of business										(93,200)
First Heritage SPV
Business Acquisition [Line Items]
Consideration transferred in business acquisition			$ 140,000
Goodwill	75,400		$ 75,365			75,400				75,400			75,400	$ 75,400
Heights SPV
Business Acquisition [Line Items]
Consideration transferred in business acquisition					$ 360,000
Goodwill	$ 265,682				$ 253,857	$ 265,682	$ 265,700			$ 265,682		265,700	$ 265,682	265,682
Equity interests acquired (as a percentage)					100.00%
Payments to acquire businesses, net of cash acquired					$ 335,000
Business combination, consideration transferred, equity interests issued and issuable					$ 25,000
Number of branches | branch					390
Number of states in which entity operates | state					11
Measurement period adjustment							(3,500)					$ 11,800		(11,825)
Accounts payable and accrued liabilities, measurement period adjustments							4,200							4,209
Measurement period adjustment, income tax receivable							$ 4,200							$ 4,209