INVESTMENT SECURITIES - Narrative (Details)	8 Months Ended	12 Months Ended
	Sep. 01, 2022 USD ($)	Dec. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, accrued interest receivable		$ 2,400,000	$ 2,600,000
Held-to-maturity securities, accrued interest receivable		$ 1,900,000	$ 1,900,000
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]		Other	Other
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]		Other	Other
Held-to-maturity, book value	$ 511,000,000
Fair Value	477,000,000	$ 405,576,000	$ 411,264,000
Available-for-sale to held-to-maturity, transfer unrealized loss	$ 34,000,000		34,000,000.0
Debt securities, available-for-sale, expected credit loss		0
Debt securities, available-for-sale, allowance for credit loss		0
Debt securities, held-to-maturity, expected credit loss		0
Debt securities, held-to-maturity, allowance for credit loss		$ 0
Number of available-for-sale securities that have unrealized losses | security		273
Number of held-to-maturity securities that have unrealized losses | security		146
Debt securities, available-for-sale, decline due to credit quality		$ 0
Proceeds from sales of investment securities available for sale		0	60,924,000
Gross realized gains on available for sale securities			24,000
Gross realized losses on securities			106,000
Asset Pledged as Collateral
Debt Securities, Available-for-sale [Line Items]
Investment securities pledged as collateral		$ 429,900,000	$ 541,800,000