INVESTMENT SECURITIES - Equity Investments (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Fair Value		$ 17.4	$ 26.1
Spring EQ
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of equity investments		9.8
Spring EQ | Other Income
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of equity investments		$ 2.5
Cred.ai
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of equity investments			6.0
Cred.ai | Other Income
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of equity investments			$ 5.4
Social Finance Inc.
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of equity investments	$ 0.7			$ 4.4