Allowance for Credit Losses - Credit risk profile of loans (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Nonperforming loans past due	90 days
Current year	$ 90,403		$ 410,976
Prior year	421,836		277,930
Two years before current year	283,523		468,277
Three years before current year	457,503		452,136
Four years before current year	441,482		208,251
Prior	636,239		486,299
Revolving Loans	192,922		211,048
Total loans	2,523,908		2,514,917
Current period gross charge offs, Total	3,241	$ 3,192
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	90,634		359,398
Prior year	345,402		268,003
Two years before current year	242,417		252,293
Three years before current year	230,675		119,148
Four years before current year	108,853		64,853
Prior	203,877		152,608
Revolving Loans	97,952		94,145
Total loans	1,319,810		1,310,448
Nonperforming Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current year			176
Prior year	332		477
Two years before current year	582		1,349
Three years before current year	1,245		771
Four years before current year	623		526
Prior	1,865		2,371
Revolving Loans	333		760
Total loans	4,980		6,430
Total other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	90,634		359,574
Prior year	345,734		268,480
Two years before current year	242,999		253,642
Three years before current year	231,920		119,919
Four years before current year	109,476		65,379
Prior	205,742		154,979
Revolving Loans	98,285		94,905
Total loans	1,324,790		1,316,878
Residential | First Liens
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	8,836		64,953
Prior year	64,486		47,930
Two years before current year	47,361		89,205
Three years before current year	88,407		69,270
Four years before current year	66,647		37,771
Prior	170,251		138,824
Revolving Loans	2,214		2,279
Total loans	448,202		450,232
Current period gross charge offs, Prior	11		221
Current period gross charge offs, Total	11		221
Residential | First Liens | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	8,836		64,953
Prior year	64,486		47,930
Two years before current year	47,361		89,205
Three years before current year	88,407		69,090
Four years before current year	66,599		37,658
Prior	168,965		136,805
Revolving Loans	2,214		2,279
Total loans	446,868		447,920
Residential | First Liens | Nonperforming Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Three years before current year			180
Four years before current year	48		113
Prior	1,286		2,019
Total loans	1,334		2,312
Residential | Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	142		966
Prior year	913		562
Two years before current year	134		1,058
Three years before current year	697		31
Four years before current year	379		181
Prior	1,425		1,257
Revolving Loans	87,408		85,443
Total loans	91,098		89,498
Current period gross charge offs, 2022			22
Current period gross charge offs, 2021	22
Current period gross charge offs, Prior	19		28
Current period gross charge offs, Revolving Loans			51
Current period gross charge offs, Total	41		101
Residential | Home Equity | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	142		966
Prior year	913		562
Two years before current year	134		1,017
Three years before current year	659		31
Four years before current year	337		143
Prior	1,309		1,149
Revolving Loans	87,090		84,723
Total loans	90,584		88,591
Residential | Home Equity | Nonperforming Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Two years before current year			41
Three years before current year	38
Four years before current year	42		38
Prior	116		108
Revolving Loans	318		720
Total loans	514		907
Residential | Junior Liens
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	2,713		16,989
Prior year	17,156		12,410
Two years before current year	11,629		12,631
Three years before current year	11,797		6,469
Four years before current year	6,055		5,260
Prior	13,421		9,375
Revolving Loans	2,744		1,578
Total loans	65,515		64,712
Current period gross charge offs, 2023			15
Current period gross charge offs, Prior	56
Current period gross charge offs, Total	56		15
Residential | Junior Liens | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	2,713		16,989
Prior year	17,156		12,371
Two years before current year	11,590		12,590
Three years before current year	11,797		6,431
Four years before current year	6,017		5,200
Prior	13,306		9,229
Revolving Loans	2,744		1,578
Total loans	65,323		64,388
Residential | Junior Liens | Nonperforming Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Prior year			39
Two years before current year	39		41
Three years before current year			38
Four years before current year	38		60
Prior	115		146
Total loans	192		324
Residential | All Other Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	1,315		17,542
Prior year	22,285		13,123
Two years before current year	10,945		6,960
Three years before current year	5,214		4,472
Four years before current year	4,151		633
Prior	2,113		1,595
Revolving Loans	202		53
Total loans	46,225		44,378
Current period gross charge offs, 2021			6
Current period gross charge offs, Total			6
Residential | All Other Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	1,315		17,542
Prior year	22,285		13,123
Two years before current year	10,945		6,960
Three years before current year	5,214		4,392
Four years before current year	4,089		628
Prior	2,102		1,559
Revolving Loans	202		53
Total loans	46,152		44,257
Residential | All Other Residential | Nonperforming Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Three years before current year			80
Four years before current year	62		5
Prior	11		36
Total loans	73		121
Consumer | Motor Vehicle
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	75,412		247,512
Prior year	230,732		187,480
Two years before current year	167,455		140,363
Three years before current year	122,978		37,441
Four years before current year	30,307		20,416
Prior	17,032		3,349
Revolving Loans	10		11
Total loans	643,926		636,572
Current period gross charge offs, 2024			478
Current period gross charge offs, 2023	358		2,692
Current period gross charge offs, 2022	574		4,839
Current period gross charge offs, 2021	1,158		1,751
Current period gross charge offs, 2020	218		587
Current period gross charge offs, Prior	118		97
Current period gross charge offs, Total	2,426		10,444
Consumer | Motor Vehicle | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	75,412		247,368
Prior year	230,436		187,134
Two years before current year	166,998		139,251
Three years before current year	121,868		37,043
Four years before current year	29,941		20,130
Prior	16,721		3,290
Revolving Loans	10		11
Total loans	641,386		634,227
Consumer | Motor Vehicle | Nonperforming Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current year			144
Prior year	296		346
Two years before current year	457		1,112
Three years before current year	1,110		398
Four years before current year	366		286
Prior	311		59
Total loans	2,540		2,345
Consumer | All Other Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	2,216		11,612
Prior year	10,162		6,975
Two years before current year	5,475		3,425
Three years before current year	2,827		2,236
Four years before current year	1,937		1,118
Prior	1,500		579
Revolving Loans	5,707		5,541
Total loans	29,824		31,486
Current period gross charge offs, 2024			50
Current period gross charge offs, 2023	51		197
Current period gross charge offs, 2022	54		121
Current period gross charge offs, 2021	45		22
Current period gross charge offs, 2020	7		16
Current period gross charge offs, Prior	1		24
Current period gross charge offs, Revolving Loans	59		182
Current period gross charge offs, Total	217		612
Consumer | All Other Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	2,216		11,580
Prior year	10,126		6,883
Two years before current year	5,389		3,270
Three years before current year	2,730		2,161
Four years before current year	1,870		1,094
Prior	1,474		576
Revolving Loans	5,692		5,501
Total loans	29,497		31,065
Consumer | All Other Consumer | Nonperforming Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current year			32
Prior year	36		92
Two years before current year	86		155
Three years before current year	97		75
Four years before current year	67		24
Prior	26		3
Revolving Loans	15		40
Total loans	$ 327		$ 421