INVESTMENT SECURITIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Gain (Loss) on Securities [Line Items]
Trading securities	$ 0
Number of available for sale investment securities | security	991
Number of available-for-sale securities unrealized loss position | security	976
Weighted average duration of MBS portfolio (in years)	5 years 10 months 24 days
Securities pledged as collateral	$ 3,300,000,000	$ 3,300,000,000
Sale of investment securities available-for-sale	0	0	$ 0
Unamortized premiums	48,100,000	56,900,000
Unaccreted discounts	17,600,000	20,900,000
Owned investment securities	3,500,000,000
Total unrealized losses on investment securities	707,900,000
Allowance for credit losses	0	0
Held-to-maturity debt securities with an amortized cost basis	1,000,000,000.0	1,100,000,000
Accrued interest	3,600,000	3,700,000
Debt securities nonaccrual	0	0
Past due held-to-maturity debt securities	1,015,168,000	1,058,565,000
Past Due
Gain (Loss) on Securities [Line Items]
Past due held-to-maturity debt securities	$ 0	$ 0