SIGNIFICANT ACCOUNTING POLICIES - Loan Servicing (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Unpaid principal balances of loans serviced		$ 582.5	$ 1,490.0
Mortgage servicing rights sold	$ 923.5
Pre-tax gain on debt securities	7.5
Debt securities, available for sale, sold	108.2
Pre-tax loss on sale of debt securities available for sale	$ 6.8
Impairment charges		$ 0.0	$ 0.0