Fair Value - Carrying Amounts and Estimated Fair Values (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	$ 333,575	$ 338,570	$ 311,864
Mortgage servicing rights	3,074	3,583	3,673
Financial liabilities
Local certificates of deposit	1,125,326	1,070,247	1,009,166
Total deposits	2,702,718	2,599,662	2,599,937
Carrying value
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	377,635	385,235	387,374
Total loans	2,283,254	2,105,424	2,056,806
Mortgage servicing rights	1,940	2,177	2,246
Financial liabilities
Local certificates of deposit	377,750	293,466	338,280
National certificates of deposit	747,576	776,781	670,886
Total deposits	1,125,326	1,070,247	1,009,166
Repurchase agreements	56,027	49,576	52,915
Federal Home Loan Bank advances	95,000	20,076	30,078
Total borrowed funds	151,027	69,652	82,993
Carrying value | Commercial |    Real estate
Financial assets
Total loans	746,558	699,537	688,027
Carrying value | Commercial | Construction
Financial assets
Total loans	87,185	86,695	70,822
Carrying value | Commercial |    Other
Financial assets
Total loans	523,624	443,944	435,563
Carrying value | Municipal
Financial assets
Total loans	62,678	51,089	58,071
Carrying value | Residential | Construction
Financial assets
Total loans	34,203	31,740	28,410
Carrying value | Residential | Term
Financial assets
Total loans	693,017	669,864	655,431
Carrying value | Home Equity
Financial assets
Total loans	116,365	103,400	101,363
Carrying value | Consumer
Financial assets
Total loans	19,624	19,155	19,119
Total Fair Value
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	333,575	338,570	311,864
Total loans	2,172,931	1,964,228	1,920,157
Mortgage servicing rights	3,074	3,583	3,673
Financial liabilities
Local certificates of deposit	360,988	362,555	319,218
National certificates of deposit	768,270	699,919	672,654
Total deposits	1,129,258	1,062,474	991,872
Repurchase agreements	55,910	49,462	52,793
Federal Home Loan Bank advances	94,914	20,074	30,074
Total borrowed funds	150,824	69,536	82,867
Total Fair Value | Commercial |    Real estate
Financial assets
Total loans	714,398	658,732	652,297
Total Fair Value | Commercial | Construction
Financial assets
Total loans	83,429	81,638	67,144
Total Fair Value | Commercial |    Other
Financial assets
Total loans	516,977	431,067	423,464
Total Fair Value | Municipal
Financial assets
Total loans	57,578	46,806	52,196
Total Fair Value | Residential | Construction
Financial assets
Total loans	33,869	31,131	27,972
Total Fair Value | Residential | Term
Financial assets
Total loans	633,247	595,033	577,982
Total Fair Value | Home Equity
Financial assets
Total loans	116,058	102,858	102,124
Total Fair Value | Consumer
Financial assets
Total loans	17,375	16,963	16,978
Total Fair Value | Level 1
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	0	0	0
Total loans	0	0	0
Mortgage servicing rights	0	0	0
Financial liabilities
Local certificates of deposit	0	0	0
National certificates of deposit	0	0	0
Total deposits	0	0	0
Repurchase agreements	0	0	0
Federal Home Loan Bank advances	0	0	0
Total borrowed funds	0	0	0
Total Fair Value | Level 1 | Commercial |    Real estate
Financial assets
Total loans	0	0	0
Total Fair Value | Level 1 | Commercial | Construction
Financial assets
Total loans	0	0	0
Total Fair Value | Level 1 | Commercial |    Other
Financial assets
Total loans	0	0	0
Total Fair Value | Level 1 | Municipal
Financial assets
Total loans	0	0	0
Total Fair Value | Level 1 | Residential | Construction
Financial assets
Total loans	0	0	0
Total Fair Value | Level 1 | Residential | Term
Financial assets
Total loans	0	0	0
Total Fair Value | Level 1 | Home Equity
Financial assets
Total loans	0	0	0
Total Fair Value | Level 1 | Consumer
Financial assets
Total loans	0	0	0
Total Fair Value | Level 2
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	333,575	338,570	311,864
Total loans	0	285	285
Mortgage servicing rights	3,074	3,583	3,673
Financial liabilities
Local certificates of deposit	360,988	362,555	319,218
National certificates of deposit	768,270	699,919	672,654
Total deposits	1,129,258	1,062,474	991,872
Repurchase agreements	55,910	49,462	52,793
Federal Home Loan Bank advances	94,914	20,074	30,074
Total borrowed funds	150,824	69,536	82,867
Total Fair Value | Level 2 | Commercial |    Real estate
Financial assets
Total loans	0	0	0
Total Fair Value | Level 2 | Commercial | Construction
Financial assets
Total loans	0	0	0
Total Fair Value | Level 2 | Commercial |    Other
Financial assets
Total loans	0	0	0
Total Fair Value | Level 2 | Municipal
Financial assets
Total loans	0	0	0
Total Fair Value | Level 2 | Residential | Construction
Financial assets
Total loans	0	0	0
Total Fair Value | Level 2 | Residential | Term
Financial assets
Total loans	0	285	285
Total Fair Value | Level 2 | Home Equity
Financial assets
Total loans	0	0	0
Total Fair Value | Level 2 | Consumer
Financial assets
Total loans	0	0	0
Total Fair Value | Level 3
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	0	0	0
Total loans	2,172,931	1,963,943	1,919,872
Mortgage servicing rights	0	0	0
Financial liabilities
Local certificates of deposit	0	0	0
National certificates of deposit	0	0	0
Total deposits	0	0	0
Repurchase agreements	0	0	0
Federal Home Loan Bank advances	0	0	0
Total borrowed funds	0	0	0
Total Fair Value | Level 3 | Commercial |    Real estate
Financial assets
Total loans	714,398	658,732	652,297
Total Fair Value | Level 3 | Commercial | Construction
Financial assets
Total loans	83,429	81,638	67,144
Total Fair Value | Level 3 | Commercial |    Other
Financial assets
Total loans	516,977	431,067	423,464
Total Fair Value | Level 3 | Municipal
Financial assets
Total loans	57,578	46,806	52,196
Total Fair Value | Level 3 | Residential | Construction
Financial assets
Total loans	33,869	31,131	27,972
Total Fair Value | Level 3 | Residential | Term
Financial assets
Total loans	633,247	594,748	577,697
Total Fair Value | Level 3 | Home Equity
Financial assets
Total loans	116,058	102,858	102,124
Total Fair Value | Level 3 | Consumer
Financial assets
Total loans	$ 17,375	$ 16,963	$ 16,978