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INVESTMENT SECURITIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Tax exempt interest income on available-for-sale securities	$ 11.3	$ 11.9	$ 10.2
Realized loss on trading securities	$ (0.5)	$ (7.0)
Mortgage Backed Securities and Collateralized Mortgage Obligations
Schedule of Available-for-sale Securities [Line Items]
Weighted average yield	3.21%	3.08%
U.S. Treasury securities | Not Designated as Hedging Instrument, Economic Hedge
Schedule of Available-for-sale Securities [Line Items]
Trading securities - U.S. Treasury securities	$ 25.0	$ 19.0

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