Loans and Allowance for Credit Losses - Amortized cost basis of loans (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	$ 81,993		$ 596,068
2023/2022	584,389		667,908
2022/2021	667,826		452,797
2021/2020	440,307		341,964
2020/2019	332,543		191,673
Prior	452,070		273,542
Loans amortized cost basis	240,347		235,631
Loans	2,799,475		2,759,583
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, 2024/2023			43
Current period gross charge-off, 2023/2022			2
Current period gross charge-off, 2022/2021	3		58
Current period gross charge-off, 2021/2020			42
Current period gross charge-off, 2020/2019			253
Current period gross charge-off, Prior	202		215
Current period gross charge-off, Total	205	$ 257	613
Commercial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Loans	1,890,609		1,849,267
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, Total	193	175
Consumer
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Loans	908,866		910,316
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, Total	12	82
Commercial and industrial | Commercial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	41,962		197,997
2023/2022	184,563		93,934
2022/2021	87,940		67,927
2021/2020	66,153		70,600
2020/2019	65,830		34,697
Prior	51,208		17,566
Loans amortized cost basis	114,039		115,600
Loans	611,695		598,321
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, 2024/2023			39
Current period gross charge-off, 2022/2021			49
Current period gross charge-off, 2021/2020			11
Current period gross charge-off, 2020/2019			247
Current period gross charge-off, Prior	164		90
Current period gross charge-off, Total	164	175	436
Commercial and industrial | Commercial | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	41,962		197,533
2023/2022	183,564		89,090
2022/2021	82,980		67,691
2021/2020	56,800		64,272
2020/2019	60,343		34,603
Prior	48,218		15,053
Loans amortized cost basis	95,175		100,239
Loans	569,042		568,481
Commercial and industrial | Commercial | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	553
2021/2020	7,810
Prior	14
Loans amortized cost basis	1,878
Loans	10,255
Commercial and industrial | Commercial | Substandard
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023			464
2023/2022	446		4,844
2022/2021	4,960		236
2021/2020	1,543		6,328
2020/2019	5,487		94
Prior	2,976		2,513
Loans amortized cost basis	16,986		15,361
Loans	32,398		29,840
Real estate construction | Commercial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	1,851		29,902
2023/2022	26,751		78,611
2022/2021	91,181		14,326
2021/2020	5,154		122
2020/2019	100
Prior	929		952
Loans amortized cost basis			121
Loans	125,966		124,034
Real estate construction | Commercial | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	1,851		29,902
2023/2022	26,751		57,944
2022/2021	70,126		14,326
2021/2020	5,154		122
2020/2019	100
Prior	929		952
Loans amortized cost basis			121
Loans	104,911		103,367
Real estate construction | Commercial | Substandard
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022			20,667
2022/2021	21,055
Loans	21,055		20,667
Residential | Real estate first mortgage | Consumer
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	5,538		72,180
2023/2022	71,933		207,177
2022/2021	203,472		218,719
2021/2020	216,781		108,100
2020/2019	106,574		33,102
Prior	117,102		87,317
Loans amortized cost basis	751		284
Loans	722,151		726,879
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, 2022/2021			9
Current period gross charge-off, Prior			40
Current period gross charge-off, Total			49
Residential | Real estate first mortgage | Consumer | Performing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	5,538		72,180
2023/2022	71,933		207,177
2022/2021	199,111		218,719
2021/2020	216,774		108,100
2020/2019	106,562		33,102
Prior	116,181		87,212
Loans amortized cost basis	751		284
Loans	716,850		726,774
Residential | Real estate first mortgage | Consumer | Nonperforming
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2022/2021	4,361
2021/2020	7
2020/2019	12
Prior	921		105
Loans	5,301		105
Residential | Real estate junior lien | Consumer
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	2,303		18,408
2023/2022	17,642		15,655
2022/2021	15,169		5,946
2021/2020	5,983		4,857
2020/2019	4,528		1,769
Prior	6,711		5,280
Loans amortized cost basis	104,546		102,219
Loans	156,882		154,134
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, Prior			77
Current period gross charge-off, Total		77	77
Residential | Real estate junior lien | Consumer | Performing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	2,059		18,408
2023/2022	17,642		15,655
2022/2021	15,169		5,946
2021/2020	5,872		4,857
2020/2019	4,528		1,769
Prior	6,394		5,280
Loans amortized cost basis	102,630		100,438
Loans	154,294		152,353
Residential | Real estate junior lien | Consumer | Nonperforming
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	244
2021/2020	111
Prior	317
Loans amortized cost basis	1,916		1,781
Loans	2,588		1,781
Commercial real estate | Commercial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	29,459		272,261
2023/2022	278,867		266,136
2022/2021	264,278		144,899
2021/2020	145,408		153,796
2020/2019	152,062		120,551
Prior	274,372		161,475
Loans amortized cost basis	8,502		7,794
Loans	1,152,948		1,126,912
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, Prior	29
Current period gross charge-off, Total	29
Commercial real estate | Commercial | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	29,459		272,261
2023/2022	272,847		265,549
2022/2021	262,017		142,027
2021/2020	140,221		153,796
2020/2019	139,105		116,861
Prior	267,003		159,454
Loans amortized cost basis	7,854		7,794
Loans	1,118,506		1,117,742
Commercial real estate | Commercial | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2020/2019	12,957
Prior	1,972		262
Loans	14,929		262
Commercial real estate | Commercial | Substandard
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	6,020		587
2022/2021	2,261		2,872
2021/2020	5,187
2020/2019			3,690
Prior	5,397		1,759
Loans amortized cost basis	648
Loans	19,513		8,908
Other revolving and installment | Consumer
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	880		5,320
2023/2022	4,633		6,395
2022/2021	5,786		980
2021/2020	828		4,489
2020/2019	3,449		1,554
Prior	1,748		952
Loans amortized cost basis	12,509		9,613
Loans	29,833		29,303
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-off, by Origination Year [Abstract]
Current period gross charge-off, 2024/2023			4
Current period gross charge-off, 2023/2022			2
Current period gross charge-off, 2022/2021	3
Current period gross charge-off, 2021/2020			31
Current period gross charge-off, 2020/2019			6
Current period gross charge-off, Prior	9		8
Current period gross charge-off, Total	12	$ 5	51
Other revolving and installment | Consumer | Performing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2024/2023	880		5,320
2023/2022	4,633		6,395
2022/2021	5,786		980
2021/2020	828		4,489
2020/2019	3,449		1,554
Prior	1,747		952
Loans amortized cost basis	12,509		9,613
Loans	29,832		$ 29,303
Other revolving and installment | Consumer | Nonperforming
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Prior	1
Loans	$ 1