Loans and Allowance for Credit Losses - Loan Balances by Year of Origination and Internally Assigned Risk Rating (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Total Loan Balance
Current fiscal year	$ 1,117,436	$ 1,271,764
Year two	1,320,936	1,214,107
Year three	1,094,225	586,544
Year four	503,703	725,517
Year five	645,502	449,759
More than five years	1,650,211	1,528,088
Revolving	1,292,135	1,381,517
Revolving-Term	29,193	26,673
Total	7,653,341	7,183,969
Current Year-to-date Gross Charge-offs
2023	830
2022	214
2021	218
2020	25
2019	3,989
2018 and Prior	18,669
Revolving	109
Revolving-Term	584
Total	24,638	11,617
Pass
Total Loan Balance
Current fiscal year	1,117,247	1,271,177
Year two	1,318,412	1,177,280
Year three	1,060,514	581,879
Year four	499,034	677,616
Year five	595,848	406,053
More than five years	1,473,853	1,313,942
Revolving	1,253,528	1,348,200
Revolving-Term	25,838	23,596
Total	7,344,274	6,799,743
Special mention
Total Loan Balance
Current fiscal year	189	0
Year two	1,681	36,547
Year three	16,493	146
Year four	224	26,394
Year five	24,920	24,765
More than five years	87,973	113,071
Revolving	4,163	20,073
Revolving-Term	172	95
Total	135,815	221,091
Substandard
Total Loan Balance
Current fiscal year	0	587
Year two	843	280
Year three	17,218	4,519
Year four	4,445	21,507
Year five	24,734	18,941
More than five years	88,385	101,043
Revolving	34,444	13,244
Revolving-Term	3,183	2,982
Total	173,252	163,103
Doubtful
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	32
Revolving	0	0
Revolving-Term	0	0
Total	0	32
Commercial Loans | Commercial real estate
Total Loan Balance
Current fiscal year	276,677	292,732
Year two	324,469	360,423
Year three	439,308	269,049
Year four	240,256	449,493
Year five	419,371	261,941
More than five years	926,636	883,535
Revolving	32,418	21,666
Revolving-Term	0	0
Total	2,659,135	2,538,839
Current Year-to-date Gross Charge-offs
2023	0
2022	0
2021	0
2020	0
2019	0
2018 and Prior	1,706
Revolving	0
Revolving-Term	0
Total	1,706	827
Commercial Loans | Commercial and industrial
Total Loan Balance
Current fiscal year	171,861	253,696
Year two	231,978	289,448
Year three	210,636	88,544
Year four	54,696	73,998
Year five	52,858	65,911
More than five years	193,905	147,273
Revolving	520,249	591,522
Revolving-Term	0	0
Total	1,436,183	1,510,392
Current Year-to-date Gross Charge-offs
2023	0
2022	0
2021	0
2020	0
2019	3,412
2018 and Prior	15,842
Revolving	0
Revolving-Term	0
Total	19,254	5,797
Commercial Loans | Commercial construction
Total Loan Balance
Current fiscal year	75,596	120,655
Year two	154,456	170,691
Year three	82,313	40,762
Year four	14,845	14,442
Year five	4,727	3,953
More than five years	4,438	4,176
Revolving	14,208	27,284
Revolving-Term	0	0
Total	350,583	381,963
Current Year-to-date Gross Charge-offs
2023	0
2022	0
2021	0
2020	0
2019	451
2018 and Prior	0
Revolving	0
Revolving-Term	0
Total	451	0
Commercial Loans | Business banking
Total Loan Balance
Current fiscal year	270,129	287,679
Year two	262,606	233,723
Year three	207,611	91,149
Year four	88,018	109,731
Year five	99,574	84,889
More than five years	334,766	292,211
Revolving	96,754	105,271
Revolving-Term	1,307	1,291
Total	1,360,765	1,205,944
Current Year-to-date Gross Charge-offs
2023	0
2022	67
2021	43
2020	1
2019	88
2018 and Prior	1,073
Revolving	34
Revolving-Term	0
Total	1,306	3,314
Commercial Loans | Pass | Commercial real estate
Total Loan Balance
Current fiscal year	276,677	292,732
Year two	323,463	360,423
Year three	433,308	267,743
Year four	237,901	422,872
Year five	383,799	227,006
More than five years	781,465	704,600
Revolving	32,418	21,666
Revolving-Term	0	0
Total	2,469,031	2,297,042
Commercial Loans | Pass | Commercial and industrial
Total Loan Balance
Current fiscal year	171,672	253,324
Year two	231,114	264,012
Year three	185,884	88,544
Year four	53,101	63,190
Year five	47,063	62,874
More than five years	183,165	138,250
Revolving	482,490	559,777
Revolving-Term	0	0
Total	1,354,489	1,429,971
Commercial Loans | Pass | Commercial construction
Total Loan Balance
Current fiscal year	75,596	120,655
Year two	154,456	159,737
Year three	82,313	40,762
Year four	14,845	6,338
Year five	151	3,953
More than five years	4,054	2,297
Revolving	14,208	27,284
Revolving-Term	0	0
Total	345,623	361,026
Commercial Loans | Pass | Business banking
Total Loan Balance
Current fiscal year	270,129	287,520
Year two	262,535	233,499
Year three	204,874	87,926
Year four	87,346	107,819
Year five	96,371	80,549
More than five years	321,360	276,843
Revolving	96,618	104,354
Revolving-Term	523	645
Total	1,339,756	1,179,155
Commercial Loans | Special mention | Commercial real estate
Total Loan Balance
Current fiscal year	0	0
Year two	1,006	0
Year three	6,000	0
Year four	0	13,187
Year five	24,887	20,090
More than five years	75,428	101,112
Revolving	0	0
Revolving-Term	0	0
Total	107,321	134,389
Commercial Loans | Special mention | Commercial and industrial
Total Loan Balance
Current fiscal year	189	0
Year two	620	25,436
Year three	10,242	0
Year four	0	5,103
Year five	0	1,885
More than five years	8,848	7,132
Revolving	4,126	19,280
Revolving-Term	0	0
Total	24,025	58,836
Commercial Loans | Special mention | Commercial construction
Total Loan Balance
Current fiscal year	0	0
Year two	0	10,954
Year three	0	0
Year four	0	8,104
Year five	0	0
More than five years	0	0
Revolving	0	0
Revolving-Term	0	0
Total	0	19,058
Commercial Loans | Special mention | Business banking
Total Loan Balance
Current fiscal year	0	0
Year two	55	157
Year three	251	146
Year four	224	0
Year five	33	2,790
More than five years	3,508	3,945
Revolving	37	793
Revolving-Term	172	95
Total	4,280	7,926
Commercial Loans | Substandard | Commercial real estate
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	1,306
Year four	2,355	13,434
Year five	10,685	14,845
More than five years	69,743	77,823
Revolving	0	0
Revolving-Term	0	0
Total	82,783	107,408
Commercial Loans | Substandard | Commercial and industrial
Total Loan Balance
Current fiscal year	0	372
Year two	244	0
Year three	14,510	0
Year four	1,595	5,705
Year five	5,795	1,152
More than five years	1,892	1,891
Revolving	33,633	12,465
Revolving-Term	0	0
Total	57,669	21,585
Commercial Loans | Substandard | Commercial construction
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	4,576	0
More than five years	384	1,879
Revolving	0	0
Revolving-Term	0	0
Total	4,960	1,879
Commercial Loans | Substandard | Business banking
Total Loan Balance
Current fiscal year	0	159
Year two	16	67
Year three	2,486	3,077
Year four	448	1,912
Year five	3,170	1,550
More than five years	9,898	11,391
Revolving	99	124
Revolving-Term	612	551
Total	16,729	18,831
Commercial Loans | Doubtful | Commercial real estate
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	0
Revolving	0	0
Revolving-Term	0	0
Total	0	0
Commercial Loans | Doubtful | Commercial and industrial
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	0
Revolving	0	0
Revolving-Term	0	0
Total	0	0
Commercial Loans | Doubtful | Commercial construction
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	0
Revolving	0	0
Revolving-Term	0	0
Total	0	0
Commercial Loans | Doubtful | Business banking
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	32
Revolving	0	0
Revolving-Term	0	0
Total	0	32
Consumer Loans | Consumer real estate
Total Loan Balance
Current fiscal year	311,887	296,948
Year two	335,462	149,003
Year three	147,850	91,613
Year four	102,041	74,583
Year five	67,890	32,031
More than five years	189,794	200,169
Revolving	552,080	553,649
Revolving-Term	24,774	23,957
Total	1,731,778	1,421,953
Current Year-to-date Gross Charge-offs
2023	0
2022	1
2021	0
2020	5
2019	1
2018 and Prior	43
Revolving	75
Revolving-Term	296
Total	421	304
Consumer Loans | Other consumer
Total Loan Balance
Current fiscal year	11,286	20,054
Year two	11,965	10,819
Year three	6,507	5,427
Year four	3,847	3,270
Year five	1,082	1,034
More than five years	672	724
Revolving	76,426	82,125
Revolving-Term	3,112	1,425
Total	114,897	124,878
Current Year-to-date Gross Charge-offs
2023	830
2022	146
2021	175
2020	19
2019	37
2018 and Prior	5
Revolving	0
Revolving-Term	288
Total	1,500	1,375
Consumer Loans | Pass | Consumer real estate
Total Loan Balance
Current fiscal year	311,887	296,900
Year two	334,879	148,790
Year three	147,652	91,477
Year four	101,999	74,155
Year five	67,402	30,658
More than five years	183,283	191,228
Revolving	551,368	552,994
Revolving-Term	22,206	21,547
Total	1,720,676	1,407,749
Consumer Loans | Pass | Other consumer
Total Loan Balance
Current fiscal year	11,286	20,046
Year two	11,965	10,819
Year three	6,483	5,427
Year four	3,842	3,242
Year five	1,062	1,013
More than five years	526	724
Revolving	76,426	82,125
Revolving-Term	3,109	1,404
Total	114,699	124,800
Consumer Loans | Special mention | Consumer real estate
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	189	882
Revolving	0	0
Revolving-Term	0	0
Total	189	882
Consumer Loans | Special mention | Other consumer
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	0
Revolving	0	0
Revolving-Term	0	0
Total	0	0
Consumer Loans | Substandard | Consumer real estate
Total Loan Balance
Current fiscal year	0	48
Year two	583	213
Year three	198	136
Year four	42	428
Year five	488	1,373
More than five years	6,322	8,059
Revolving	712	655
Revolving-Term	2,568	2,410
Total	10,913	13,322
Consumer Loans | Substandard | Other consumer
Total Loan Balance
Current fiscal year	0	8
Year two	0	0
Year three	24	0
Year four	5	28
Year five	20	21
More than five years	146	0
Revolving	0	0
Revolving-Term	3	21
Total	198	78
Consumer Loans | Doubtful | Consumer real estate
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	0
Revolving	0	0
Revolving-Term	0	0
Total	0	0
Consumer Loans | Doubtful | Other consumer
Total Loan Balance
Current fiscal year	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	0
Revolving	0	0
Revolving-Term	0	0
Total	$ 0	$ 0