INVESTMENT SECURITIES - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($) security	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) security	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Schedule of Investments [Line Items]
Number of available for sale investment securities | security	1,009		1,009
Number of available-for-sale securities unrealized loss position | security	954		954
Sale of investment securities available-for-sale			$ 0	$ 0
Unamortized premiums	$ 42,100,000		42,100,000		$ 48,100,000
Unaccreted discounts	17,100,000		17,100,000		17,600,000
Allowance for credit losses	0		0		0
Held-to-maturity debt securities with an amortized cost basis	1,000,000,000.0		1,000,000,000.0		1,000,000,000.0
Accrued interest	3,000,000.0		3,000,000.0		3,600,000
Debt securities nonaccrual	0		0		0
Past due held-to-maturity debt securities	979,704,000		979,704,000		1,015,168,000
Fair value	17,700,000		17,700,000		18,200,000
Realized gain on sale of equity investments, net	939,000	$ 56,000	957,000	$ 2,186,000
Asset Pledged as Collateral
Schedule of Investments [Line Items]
Investment securities, pledged for collateral	3,700,000,000		3,700,000,000		3,300,000,000
Past Due
Schedule of Investments [Line Items]
Past due held-to-maturity debt securities	$ 0		$ 0		$ 0