BORROWED FUNDS - Short-term borrowings - Additional information (Details) - USD ($)	Mar. 31, 2025	Dec. 31, 2024
BORROWED FUNDS
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.10%	0.10%
Short-term borrowings	$ 571,000	$ 2,488,000
Other Assets [Member]
BORROWED FUNDS
Federal Home Loan Bank Stock	6,311,000	6,299,000
Other Correspondent Banks
BORROWED FUNDS
Line of Credit Facility, Maximum Borrowing Capacity	75,000,000	75,000,000
Long-term Line of Credit, Total	0	0
Federal Reserve Bank of Philadelphia
BORROWED FUNDS
Line of Credit Facility, Current Borrowing Capacity	17,431,000	18,093,000
Long-term Line of Credit, Total	0	0
Investment pledged as collateral	$ 18,236,000	$ 18,881,000
Customer repurchase agreements
BORROWED FUNDS
Debt, Weighted Average Interest Rate	0.10%	0.10%
Carrying Value of Securities Sold under Repurchase Agreements and Deposits Received for Securities Loaned, Total	$ 580,000	$ 2,500,000
Short-term borrowings	571,000	2,488,000
FHLB-Pittsburgh borrowings
BORROWED FUNDS
Short-term borrowings	0	0
Federal Home Loan Bank of Pittsburgh
BORROWED FUNDS
Line of Credit Facility, Maximum Borrowing Capacity	948,970,000	938,691,000
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	1,347,840,000	1,351,770,000
Line of Credit Facility, Remaining Borrowing Capacity	772,430,000	749,999,000
Federal Home Loan Bank of Pittsburgh | Other Assets [Member]
BORROWED FUNDS
Federal Home Loan Bank Stock	$ 14,834,000	$ 15,018,000