BORROWINGS - Additional Information (Details)	1 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2024 USD ($) agreement	Dec. 31, 2023 USD ($) agreement	Dec. 31, 2007 USD ($) security
Debt Instrument [Line Items]
Prepayments of the FHLB borrowings		$ 2,000,000,000	$ 1,800,000,000
Remaining borrowing capacity		1,100,000,000	993,800,000
Naming applicable municipalities as beneficiaries		155,500,000	155,700,000
Loans receivable		4,479,692,000	4,468,476,000
Maximum amount of Open Repo borrowing available		0	0
Unamortized debt issuance costs		600,000	700,000
Federal Home Loan Bank, Advances, Open Repo Borrowings
Debt Instrument [Line Items]
Federal home loan balance		$ 250,000,000	250,000,000
Commitment term		364 days
Maximum amount of Open Repo borrowing available		$ 0	0
Federal Reserve Bank Advances | Federal Reserve BIC Program
Debt Instrument [Line Items]
Federal home loan balance		233,000,000
Prepayments of the FHLB borrowings		78,200,000
Loans receivable		240,500,000
Maximum amount of Open Repo borrowing available		$ 0	$ 0
Subordinated Debt
Debt Instrument [Line Items]
Number of preferred trust securities | security				2
Floating rate trust preferred securities				$ 10,000,000
Effective percentage		7.15%	7.20%
Trust preferred securities, interest payment deferment period		5 years
Subordinated Debt | Notes Maturing In June 2031
Debt Instrument [Line Items]
Floating rate trust preferred securities	$ 85,000,000
Interest rate, percentage	3.25%
Proceeds from issuance of subordinated notes, net of issuance costs	$ 83,500,000
Subordinated Debt | SOFR
Debt Instrument [Line Items]
Line of credit, basis spread on variable rate		1.55%
Credit spread adjustment (as percent)		0.26161%
Subordinated Debt | SOFR | Notes Maturing In June 2031
Debt Instrument [Line Items]
Line of credit, basis spread on variable rate		2.58%
Subordinated Debt | LIBOR
Debt Instrument [Line Items]
Line of credit, basis spread on variable rate				1.55%
Line of Credit | Overnight Borrowing Agreements
Debt Instrument [Line Items]
Line of credit, outstanding amount		$ 0	$ 0
Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Number of unsecured lines of credit issued | agreement		1	1
Pledge on certain loan amount		$ 10,000,000	$ 10,000,000
Line of credit, outstanding amount		$ 0	$ 0
Line of Credit | Unsecured Debt | SOFR
Debt Instrument [Line Items]
Line of credit, basis spread on variable rate		2.85%