Loans and Allowance for Credit Losses - Summary of Internal Risk-rating Categories (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	$ 1,321,045		$ 1,321,045		$ 3,481,250
2022	3,168,009		3,168,009		2,447,552
2021	2,297,685		2,297,685		1,630,538
2020	1,487,420		1,487,420		1,094,274
2019	975,924		975,924		779,687
Prior	2,959,855		2,959,855		2,496,108
Revolving Loans	1,671,645		1,671,645		1,614,995
Revolving Loans Converted to Term Loans	18,385		18,385		18,124
Total	13,899,968		13,899,968		13,562,528
Current period gross charge-offs
Total	1,045	$ 983	2,801	$ 3,689
Commercial and industrial | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	429,563		429,563		780,736
2022	519,855		519,855		490,827
2021	394,074		394,074		425,901
2020	365,394		365,394		204,752
2019	160,891		160,891		103,461
Prior	659,476		659,476		647,702
Revolving Loans	539,086		539,086		478,083
Revolving Loans Converted to Term Loans	4,011		4,011		1,066
Total	3,072,350		3,072,350		3,132,528
Current period gross charge-offs
2023			0
2022			0
2021			0
2020			0
2019			0
Prior			11
Revolving Loans			0
Revolving Loans Converted to Term Loans			0
Total	11	11	11	13
Commercial and industrial | Pass | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	421,454		421,454		778,144
2022	489,139		489,139		479,317
2021	377,921		377,921		415,990
2020	351,075		351,075		199,865
2019	160,669		160,669		100,716
Prior	656,163		656,163		639,825
Revolving Loans	497,576		497,576		473,148
Revolving Loans Converted to Term Loans	3,555		3,555		50
Total	2,957,552		2,957,552		3,087,055
Commercial and industrial | Special Mention | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	8,109		8,109		2,298
2022	30,704		30,704		1,307
2021	14,345		14,345		7,267
2020	13,897		13,897		4,841
2019	186		186		147
Prior	633		633		0
Revolving Loans	18,711		18,711		1,196
Revolving Loans Converted to Term Loans	456		456		670
Total	87,041		87,041		17,726
Commercial and industrial | Substandard | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		294
2022	12		12		4,954
2021	1,808		1,808		2,644
2020	422		422		46
2019	36		36		2,598
Prior	2,672		2,672		7,854
Revolving Loans	22,799		22,799		485
Revolving Loans Converted to Term Loans	0		0		346
Total	27,749		27,749		19,221
Commercial and industrial | Doubtful | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		5,249
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	8		8		23
Revolving Loans	0		0		3,254
Revolving Loans Converted to Term Loans	0		0		0
Total	8		8		8,526
Commercial and industrial | Loss | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Commercial real estate | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	372,774		372,774		1,510,675
2022	1,467,477		1,467,477		825,620
2021	873,581		873,581		589,959
2020	580,368		580,368		605,840
2019	577,648		577,648		501,194
Prior	1,451,637		1,451,637		1,053,298
Revolving Loans	67,157		67,157		60,590
Revolving Loans Converted to Term Loans	2,585		2,585		4,187
Total	5,393,227		5,393,227		5,151,363
Current period gross charge-offs
2023			0
2022			0
2021			0
2020			0
2019			0
Prior			0
Revolving Loans			0
Revolving Loans Converted to Term Loans			0
Total	0	0	0	0
Commercial real estate | Pass | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	372,774		372,774		1,510,675
2022	1,467,477		1,467,477		825,620
2021	858,225		858,225		586,567
2020	575,634		575,634		581,840
2019	524,549		524,549		461,296
Prior	1,342,646		1,342,646		1,006,160
Revolving Loans	59,152		59,152		52,590
Revolving Loans Converted to Term Loans	2,585		2,585		4,187
Total	5,203,042		5,203,042		5,028,935
Commercial real estate | Special Mention | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		771
2020	744		744		4,204
2019	2,395		2,395		15,366
Prior	28,343		28,343		12,255
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	31,482		31,482		32,596
Commercial real estate | Substandard | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	15,356		15,356		2,621
2020	3,990		3,990		19,796
2019	50,704		50,704		24,532
Prior	54,851		54,851		34,883
Revolving Loans	8,005		8,005		8,000
Revolving Loans Converted to Term Loans	0		0		0
Total	132,906		132,906		89,832
Commercial real estate | Doubtful | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	25,797		25,797		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	25,797		25,797		0
Commercial real estate | Loss | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Commercial construction | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	105,025		105,025		91,397
2022	140,590		140,590		178,648
2021	124,288		124,288		31,317
2020	7		7		20,767
2019	0		0		0
Prior	0		0		0
Revolving Loans	10,727		10,727		12,130
Revolving Loans Converted to Term Loans	0		0		0
Total	380,637		380,637		334,259
Current period gross charge-offs
2023			0
2022			0
2021			0
2020			0
2019			0
Prior			0
Revolving Loans			0
Revolving Loans Converted to Term Loans			0
Total	0	0	0	0
Commercial construction | Pass | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	99,843		99,843		91,397
2022	140,590		140,590		178,648
2021	124,288		124,288		28,956
2020	0		0		20,767
2019	0		0		0
Prior	0		0		0
Revolving Loans	10,727		10,727		12,130
Revolving Loans Converted to Term Loans	0		0		0
Total	375,448		375,448		331,898
Commercial construction | Special Mention | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	5,182		5,182		0
2022	0		0		0
2021	0		0		2,361
2020	7		7		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	5,189		5,189		2,361
Commercial construction | Substandard | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Commercial construction | Doubtful | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Commercial construction | Loss | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Business banking | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	109,351		109,351		178,806
2022	165,680		165,680		206,703
2021	192,765		192,765		176,147
2020	158,293		158,293		135,731
2019	123,411		123,411		63,762
Prior	264,664		264,664		248,643
Revolving Loans	73,608		73,608		80,455
Revolving Loans Converted to Term Loans	4,044		4,044		4,991
Total	1,091,816		1,091,816		1,095,238
Current period gross charge-offs
2023			0
2022			111
2021			62
2020			56
2019			102
Prior			250
Revolving Loans			23
Revolving Loans Converted to Term Loans			296
Total	303	369	900	1,922
Business banking | Pass | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	107,950		107,950		178,806
2022	164,497		164,497		202,230
2021	187,765		187,765		170,088
2020	152,567		152,567		128,282
2019	117,485		117,485		59,452
Prior	252,479		252,479		233,484
Revolving Loans	71,942		71,942		78,080
Revolving Loans Converted to Term Loans	3,433		3,433		4,770
Total	1,058,118		1,058,118		1,055,192
Business banking | Special Mention | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	572		572		991
2021	1,446		1,446		4,635
2020	3,579		3,579		4,605
2019	3,778		3,778		3,740
Prior	8,233		8,233		7,584
Revolving Loans	1,019		1,019		145
Revolving Loans Converted to Term Loans	27		27		0
Total	18,654		18,654		21,700
Business banking | Substandard | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	1,401		1,401		0
2022	611		611		3,482
2021	3,554		3,554		1,424
2020	2,127		2,127		2,663
2019	1,069		1,069		570
Prior	3,452		3,452		7,505
Revolving Loans	647		647		2,230
Revolving Loans Converted to Term Loans	584		584		221
Total	13,445		13,445		18,095
Business banking | Doubtful | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	20		20		181
2019	1,079		1,079		0
Prior	500		500		70
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	1,599		1,599		251
Business banking | Loss | Commercial Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Residential real estate | Residential Real Estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	204,250		204,250		766,094
2022	747,699		747,699		702,429
2021	677,289		677,289		383,651
2020	364,515		364,515		103,747
2019	96,601		96,601		70,668
Prior	478,427		478,427		453,466
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	2,568,781		2,568,781		2,480,055
Current period gross charge-offs
2023			0
2022			0
2021			0
2020			0
2019			0
Prior			0
Revolving Loans			0
Revolving Loans Converted to Term Loans			0
Total	0	0	0	0
Residential real estate | Residential Real Estate | Current and accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	203,704		203,704		761,442
2022	742,941		742,941		696,959
2021	672,492		672,492		382,262
2020	362,610		362,610		99,494
2019	95,373		95,373		66,702
Prior	464,070		464,070		434,720
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	2,541,190		2,541,190		2,441,579
Residential real estate | Residential Real Estate | 30-89 days past due and accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	441		441		4,652
2022	4,032		4,032		5,470
2021	4,343		4,343		1,245
2020	905		905		2,762
2019	940		940		2,951
Prior	8,855		8,855		11,646
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	19,516		19,516		28,726
Residential real estate | Residential Real Estate | Loans 90 days or more past due and still accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Residential real estate | Residential Real Estate | Non-accrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	105		105		0
2022	726		726		0
2021	454		454		144
2020	1,000		1,000		1,491
2019	288		288		1,015
Prior	5,502		5,502		7,100
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	8,075		8,075		9,750
Consumer home equity | Consumer Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	27,721		27,721		97,954
2022	87,217		87,217		10,774
2021	9,557		9,557		5,840
2020	5,189		5,189		5,076
2019	4,356		4,356		21,438
Prior	87,374		87,374		76,174
Revolving Loans	968,009		968,009		966,188
Revolving Loans Converted to Term Loans	7,584		7,584		7,863
Total	1,197,007		1,197,007		1,191,307
Current period gross charge-offs
2023			0
2022			0
2021			0
2020			0
2019			0
Prior			0
Revolving Loans			7
Revolving Loans Converted to Term Loans			0
Total	0	0	7	0
Consumer home equity | Consumer Portfolio Segment | Current and accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	27,721		27,721		97,395
2022	86,954		86,954		10,774
2021	9,557		9,557		5,840
2020	5,189		5,189		5,015
2019	4,356		4,356		21,092
Prior	84,939		84,939		73,927
Revolving Loans	954,862		954,862		953,829
Revolving Loans Converted to Term Loans	7,028		7,028		7,320
Total	1,180,606		1,180,606		1,175,192
Consumer home equity | Consumer Portfolio Segment | 30-89 days past due and accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		559
2022	196		196		0
2021	0		0		0
2020	0		0		0
2019	0		0		72
Prior	647		647		944
Revolving Loans	7,675		7,675		7,239
Revolving Loans Converted to Term Loans	377		377		247
Total	8,895		8,895		9,061
Consumer home equity | Consumer Portfolio Segment | Loans 90 days or more past due and still accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Consumer home equity | Consumer Portfolio Segment | Non-accrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	67		67		0
2021	0		0		0
2020	0		0		61
2019	0		0		274
Prior	1,788		1,788		1,303
Revolving Loans	5,472		5,472		5,120
Revolving Loans Converted to Term Loans	179		179		296
Total	7,506		7,506		7,054
Other Consumer | Consumer Portfolio Segment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	72,361		72,361		55,588
2022	39,491		39,491		32,551
2021	26,131		26,131		17,723
2020	13,654		13,654		18,361
2019	13,017		13,017		19,164
Prior	18,277		18,277		16,825
Revolving Loans	13,058		13,058		17,549
Revolving Loans Converted to Term Loans	161		161		17
Total	196,150		196,150		177,778
Current period gross charge-offs
2023			746
2022			307
2021			296
2020			90
2019			84
Prior			200
Revolving Loans			160
Revolving Loans Converted to Term Loans			0
Total	731	$ 603	1,883	$ 1,754
Other Consumer | Consumer Portfolio Segment | Current and accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	72,222		72,222		55,414
2022	39,286		39,286		32,390
2021	26,060		26,060		17,641
2020	13,635		13,635		18,298
2019	12,949		12,949		18,832
Prior	18,047		18,047		16,603
Revolving Loans	13,030		13,030		17,476
Revolving Loans Converted to Term Loans	112		112		0
Total	195,341		195,341		176,654
Other Consumer | Consumer Portfolio Segment | 30-89 days past due and accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	126		126		143
2022	143		143		68
2021	61		61		43
2020	19		19		61
2019	68		68		240
Prior	183		183		178
Revolving Loans	28		28		58
Revolving Loans Converted to Term Loans	0		0		7
Total	628		628		798
Other Consumer | Consumer Portfolio Segment | Loans 90 days or more past due and still accruing
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		0
Other Consumer | Consumer Portfolio Segment | Non-accrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023	13		13		31
2022	62		62		93
2021	10		10		39
2020	0		0		2
2019	0		0		92
Prior	47		47		44
Revolving Loans	0		0		15
Revolving Loans Converted to Term Loans	49		49		10
Total	$ 181		$ 181		$ 326