BORROWED FUNDS - Short-term borrowings - Additional information (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
BORROWED FUNDS
Short-term borrowings	$ 11,426,000	$ 33,874,000
Other Assets [Member]
BORROWED FUNDS
Federal Home Loan Bank Stock	6,288,000	6,252,000
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	18,602,000	19,982,000
Long-term Line of Credit, Total	0	0
Investment pledged as collateral	$ 19,387,000	$ 20,829,000
Short-term advances
BORROWED FUNDS
Short-term Debt, Weighted Average Interest Rate, at Point in Time	5.29%	5.60%
Long-term Line of Credit, Total	$ 10,000,000	$ 25,000,000
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	$ 1,440,000	$ 2,400,000
Short-term borrowings	1,426,000	$ 2,374,000
FHLB-Pittsburgh borrowings
BORROWED FUNDS
Short-term Debt, Weighted Average Interest Rate, at Point in Time		5.68%
Long-term Line of Credit, Total		$ 6,500,000
Short-term borrowings	10,000,000	31,500,000
Federal Home Loan Bank of Pittsburgh
BORROWED FUNDS
Line of Credit Facility, Maximum Borrowing Capacity	945,142,000	926,845,000
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	1,337,673,000	1,323,008,000
Line of Credit Facility, Remaining Borrowing Capacity	737,284,000	737,824,000
Federal Home Loan Bank of Pittsburgh | Other Assets [Member]
BORROWED FUNDS
Federal Home Loan Bank Stock	$ 15,971,000	$ 15,214,000