INVESTMENT SECURITIES - Narrative (Details) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($)	Jun. 30, 2024 USD ($)	Sep. 30, 2023	Dec. 31, 2022 USD ($) fund	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Number of bank technology funds | fund				2
Debt securities pledged as collateral		$ 37,400			$ 45,100
Shareholder equity held by one issuer (as a percent)		10.00%	10.00%
Accrued interest receivable		$ 11,339			11,428
Bank Technology Fund
Debt Securities, Available-for-sale [Line Items]
Contractual obligation				$ 6,000
Payments to partnership fund		200
Balance with SBIC included in other assets		2,200
Committed investments to be made in the future		3,800
Debt securities pledged as collateral		10,100			39,300
Bank Technology Fund | Other Assets
Debt Securities, Available-for-sale [Line Items]
Contribution to committed investments	$ 800
Small Business Investment Company ("SBIC")
Debt Securities, Available-for-sale [Line Items]
Contractual obligation		600
Return of capital, received	100	200
Small Business Investment Company ("SBIC") | Other Assets
Debt Securities, Available-for-sale [Line Items]
Contribution to committed investments	$ 200	200
Balance with SBIC included in other assets		2,400			2,200
Held-to-Maturity Securities
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable		$ 400			$ 400