Loans, Allowance for Credit Losses and Credit Quality - Financing Receivable Past Due (Details) $ in Thousands		Jun. 30, 2026 USD ($) loan	Dec. 31, 2025 USD ($) loan
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		611	716
Total loans	[1],[2]	$ 18,394,327	$ 18,503,777
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		59	62
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		99	89
Number Of Financing Receivables Total Past Due | loan		769	867
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 17,184	$ 24,766
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		39,455	8,814
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		23,293	26,482
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		79,932	60,062
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 18,314,395	$ 18,443,715
Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		19	36
Total loans	[1],[2],[3]	$ 4,730,827	$ 4,611,789
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		16	18
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		48	35
Number Of Financing Receivables Total Past Due | loan		83	89
Commercial And Industrial [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 5,472	$ 7,765
Commercial And Industrial [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		4,067	3,627
Commercial And Industrial [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		7,836	5,776
Commercial And Industrial [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		17,375	17,168
Commercial And Industrial [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 4,713,452	$ 4,594,621
Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		5	15
Total loans	[1],[2],[3]	$ 7,944,099	$ 8,275,408
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		5	3
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		6	7
Number Of Financing Receivables Total Past Due | loan		16	25
Commercial Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 1,508	$ 7,037
Commercial Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		27,627	619
Commercial Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		5,211	10,103
Commercial Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		34,346	17,759
Commercial Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 7,909,753	$ 8,257,649
Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		1	1
Total loans	[1],[2]	$ 1,464,449	$ 1,399,193
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		2	1
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		2	2
Number Of Financing Receivables Total Past Due | loan		5	4
Construction Loans [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 802	$ 804
Construction Loans [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		878	488
Construction Loans [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		2,925	3,693
Construction Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		4,605	4,985
Construction Loans [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 1,459,844	$ 1,394,208
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		28	20
Total loans	[1],[2]	$ 2,870,277	$ 2,873,443
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		22	16
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		19	18
Number Of Financing Receivables Total Past Due | loan		69	54
Residential Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 8,117	$ 5,592
Residential Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		5,665	3,597
Residential Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		3,559	3,278
Residential Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		17,341	12,467
Residential Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 2,852,936	$ 2,860,976
Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		18	20
Total loans	[1],[2]	$ 1,342,797	$ 1,297,662
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		8	9
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		23	24
Number Of Financing Receivables Total Past Due | loan		49	53
Home Equity Loan [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 975	$ 3,247
Home Equity Loan [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		1,213	456
Home Equity Loan [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		3,761	3,629
Home Equity Loan [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		5,949	7,332
Home Equity Loan [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 1,336,848	$ 1,290,330
Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan	[4]	540	624
Total loans	[2],[4]	$ 41,878	$ 46,282
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan	[4]	6	15
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan	[4]	1	3
Number Of Financing Receivables Total Past Due | loan	[4]	547	642
Consumer - Other [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[4]	$ 310	$ 321
Consumer - Other [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[4]	5	27
Consumer - Other [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[4]	1	3
Consumer - Other [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans	[4]	316	351
Consumer - Other [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans	[4]	$ 41,562	$ 45,931

[1] (2)Loan origination dates in the tables above reflect the original origination date, or the date of a material modification of a previously originated loan.

[2] The amount of net deferred fees/costs on originated loans included in the ending balance was $9.6 million and $7.7 million at June 30, 2026 and December 31, 2025, respectively. Net unamortized discounts on acquired loans included in the ending balance were $143.5 million and $157.0 million at June 30, 2026 and December 31, 2025, respectively.

[3]

[4] Other consumer portfolio is inclusive of deposit account overdrafts recorded as loan balances. (2)The amount of net deferred fees/costs on originated loans included in the ending balance was $9.6 million and $7.7 million at June 30, 2026 and December 31, 2025, respectively. Net unamortized discounts on acquired loans included in the ending balance were $143.5 million and $157.0 million at June 30, 2026 and December 31, 2025, respectively.