BORROWINGS - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) bank	Dec. 31, 2022 USD ($)	Oct. 11, 2023 USD ($)	Oct. 10, 2023 USD ($)
Debt Instrument [Line Items]
Residential real estate loans and securities pledged as collateral for FHLB advances, carrying value	$ 824,000,000	$ 549,000,000
FHLB stock	18,000,000.0	12,400,000
FHLB borrowing capacity, authorized	800,000,000.0	800,000,000.0
Commercial loans pledged as collateral for federal reserve discount window	1,590,000,000	928,600,000
Federal reserve borrowing capacity	1,260,000,000	758,300,000
Remaining borrowing capacity	$ 325,000,000	350,000,000.0
Number of banks | bank	11
Proceeds from lines of credit	$ 0	22,000,000
Federal Funds purchased	0	22,000,000
American Financial Exchange
Debt Instrument [Line Items]
Remaining borrowing capacity	319,000,000.0	319,000,000.0
Federal Funds purchased	0	$ 0
Pledged as Collateral
Debt Instrument [Line Items]
Securities borrowed collateral value	$ 150,500,000
FHLB of Indianapolis Bullet Advance
Debt Instrument [Line Items]
Interest rate	5.55%	4.21%
Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Current borrowing capacity	$ 574,900,000	$ 574,900,000
Borrowings	0	0
Line of Credit
Debt Instrument [Line Items]
Borrowings	$ 0	$ 0
Line of Credit | Unsecured Revolving Credit Agreement
Debt Instrument [Line Items]
Borrowing capacity			$ 30,000,000
Debt instrument, term	1 year
Line of Credit | Previous Credit Agreement
Debt Instrument [Line Items]
Borrowing capacity				$ 12,500,000