Fair Value - Carrying Amounts and Estimated Fair Values (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	$ 321,616	$ 338,570	$ 336,007
Mortgage servicing rights	3,281	3,583	3,639
Financial liabilities
Local certificates of deposit	1,111,739	1,070,247	1,049,629
Total deposits	2,578,080	2,599,662	2,499,862
Carrying value
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	377,522	385,235	389,987
Total loans	2,222,977	2,105,424	2,037,488
Mortgage servicing rights	2,019	2,177	2,313
Financial liabilities
Local certificates of deposit	369,948	293,466	332,390
National certificates of deposit	741,791	776,781	717,239
Total deposits	1,111,739	1,070,247	1,049,629
Repurchase agreements	56,502	49,576	48,401
Federal Home Loan Bank advances	174,118	20,076	66,080
Total borrowed funds	230,620	69,652	114,481
Carrying value | Commercial |    Real estate
Financial assets
Total loans	738,022	699,537	688,497
Carrying value | Commercial | Construction
Financial assets
Total loans	97,804	86,695	62,625
Carrying value | Commercial |    Other
Financial assets
Total loans	477,978	443,944	438,945
Carrying value | Municipal
Financial assets
Total loans	61,925	51,089	57,853
Carrying value | Residential | Construction
Financial assets
Total loans	34,987	31,740	30,203
Carrying value | Residential | Term
Financial assets
Total loans	680,446	669,864	640,296
Carrying value | Home Equity
Financial assets
Total loans	111,484	103,400	99,031
Carrying value | Consumer
Financial assets
Total loans	20,331	19,155	20,038
Total Fair Value
Financial assets
Securities to be held to maturity (net of allowance for credit losses)	321,616	338,570	336,007
Total loans	2,094,743	1,964,228	1,913,868
Mortgage servicing rights	3,281	3,583	3,639
Financial liabilities
Local certificates of deposit	350,698	362,555	311,328
National certificates of deposit	750,751	699,919	719,323
Total deposits	1,101,449	1,062,474	1,030,651
Repurchase agreements	56,372	49,462	48,293
Federal Home Loan Bank advances	123,851	20,074	66,050
Total borrowed funds	180,223	69,536	114,343
Total Fair Value | Commercial |    Real estate
Financial assets
Total loans	700,230	658,732	653,180
Total Fair Value | Commercial | Construction
Financial assets
Total loans	92,796	81,638	59,413
Total Fair Value | Commercial |    Other
Financial assets
Total loans	468,464	431,067	427,185
Total Fair Value | Municipal
Financial assets
Total loans	59,216	46,806	53,169
Total Fair Value | Residential | Construction
Financial assets
Total loans	34,556	31,131	30,089
Total Fair Value | Residential | Term
Financial assets
Total loans	610,008	595,033	572,873
Total Fair Value | Home Equity
Financial assets
Total loans	111,424	102,858	99,975
Total Fair Value | Consumer
Financial assets
Total loans	18,049	16,963	17,984
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)	321,616	338,570	336,007
Total loans	0	285	215
Mortgage servicing rights	3,281	3,583	3,639
Financial liabilities
Local certificates of deposit	350,698	362,555	311,328
National certificates of deposit	750,751	699,919	719,323
Total deposits	1,101,449	1,062,474	1,030,651
Repurchase agreements	56,372	49,462	48,293
Federal Home Loan Bank advances	123,851	20,074	66,050
Total borrowed funds	180,223	69,536	114,343
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	215
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	0
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	2,094,743	1,963,943	1,913,653
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	700,230	658,732	653,180
Total Fair Value | Level 3 | Commercial | Construction
Financial assets
Total loans	92,796	81,638	59,413
Total Fair Value | Level 3 | Commercial |    Other
Financial assets
Total loans	468,464	431,067	426,970
Total Fair Value | Level 3 | Municipal
Financial assets
Total loans	59,216	46,806	53,169
Total Fair Value | Level 3 | Residential | Construction
Financial assets
Total loans	34,556	31,131	30,089
Total Fair Value | Level 3 | Residential | Term
Financial assets
Total loans	610,008	594,748	572,873
Total Fair Value | Level 3 | Home Equity
Financial assets
Total loans	111,424	102,858	99,975
Total Fair Value | Level 3 | Consumer
Financial assets
Total loans	$ 18,049	$ 16,963	$ 17,984