Borrowed Funds - Short-term Borrowings, Long-term borrowings and Repurchase Agreements (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Borrowed funds
FHLB maximum borrowing capacity	$ 689,000,000.0
FHLB, remaining borrowing capacity	675,900,000
FHLB, deposit letters of credit	11,900,000
FHLB, credit enhancement recourse obligations	1,200,000
Short-term Borrowings and Repurchase Agreements
Long-term notes from the FHLB	0	$ 0
Short-term Borrowings from FHLB
Short-term Borrowings and Repurchase Agreements
Balance at end of period	0	0
Average balance during the period	29,000	17,542,000
Maximum month-end balance	$ 0	$ 0
Weighted-average rate during the period	5.99%	5.07%
Weighted-average rate at end of period	0.00%	0.00%
Federal Funds Purchased
Short-term Borrowings and Repurchase Agreements
Balance at end of period	$ 0	$ 0
Investment Securities
Short-term Borrowings and Repurchase Agreements
Investment securities held as collateral	4,900,000	4,900,000
Repurchase Agreements
Short-term Borrowings and Repurchase Agreements
Balance at end of period	4,755,000	4,821,000
Average balance during the period	3,334,000	5,662,000
Maximum month-end balance	$ 4,755,000	$ 10,041,000
Weighted-average rate during the period	0.92%	0.02%
Weighted-average rate at end of period	2.37%	0.01%