Loans, Allowance for Credit Losses and Credit Quality - Financing Receivable Past Due (Details) $ in Thousands		Jun. 30, 2024 USD ($) loan		Dec. 31, 2023 USD ($) loan	Jun. 30, 2023 USD ($)
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		466		480
Total loans		$ 14,400,942	[1]	$ 14,278,070
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		37		29
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		38		40
Number Of Financing Receivables Total Past Due | loan		541		549
Total		$ 14,400,942		$ 14,278,070	$ 14,139,911
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		6,472		23,616
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		4,553		29,433
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		41,623		10,305
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		52,648		63,354
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 14,348,294		$ 14,214,716
Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		5		6
Total loans		$ 1,602,752	[1]	$ 1,579,986
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		5		2
Number Of Financing Receivables Total Past Due | loan		12		9
Total		$ 1,602,752		$ 1,579,986	1,723,219	[1]
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Commercial And Industrial [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		164		398
Commercial And Industrial [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		147		17,538
Commercial And Industrial [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		17,782		673
Commercial And Industrial [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		18,093		18,609
Commercial And Industrial [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 1,584,659		$ 1,561,377
Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		4		8
Total loans		$ 8,151,805	[1]	$ 8,041,508
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		2		2
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		3		3
Number Of Financing Receivables Total Past Due | loan		9		13
Total		$ 8,151,805		$ 8,041,508	7,812,796	[1]
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Commercial Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		1,483		14,674
Commercial Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		1,745		8,419
Commercial Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		19,422		7,279
Commercial Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		22,650		30,372
Commercial Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 8,129,155		$ 8,011,136
Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		0		0
Total loans		$ 786,743	[1]	$ 849,586
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		0		0
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		0		0
Number Of Financing Receivables Total Past Due | loan		0		0
Total		$ 786,743		$ 849,586	1,022,796	[1]
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Construction Loans [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0		0
Construction Loans [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0		0
Construction Loans [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0		0
Construction Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		0		0
Construction Loans [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 786,743		$ 849,586
Small Business [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		9		6
Total loans		$ 269,270	[1]	$ 251,956
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		5		1
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		7		6
Number Of Financing Receivables Total Past Due | loan		21		13
Total		$ 269,270		$ 251,956	237,092	[1]
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Small Business [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		205		400
Small Business [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		236		20
Small Business [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		122		243
Small Business [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		563		663
Small Business [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 268,707		$ 251,293
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		15		24
Total loans		$ 2,439,646	[1]	$ 2,424,754
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		9		7
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		7		13
Number Of Financing Receivables Total Past Due | loan		31		44
Total		$ 2,439,646		$ 2,424,754	2,221,284	[1]
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Residential Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		3,422		6,216
Residential Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		2,037		2,187
Residential Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		1,583		1,573
Residential Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		7,042		9,976
Residential Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 2,432,604		$ 2,414,778
Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		9		23
Total loans	[1]	$ 1,116,807
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		4		4
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		15		10
Number Of Financing Receivables Total Past Due | loan		28		37
Total		$ 1,116,807		$ 1,097,626	$ 1,095,398	[1]
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Home Equity Loan [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		939		1,640
Home Equity Loan [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		333		1,238
Home Equity Loan [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		2,713		529
Home Equity Loan [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		3,985		3,407
Home Equity Loan [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 1,112,822		$ 1,094,219
Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan	[2]	424		413
Total loans		$ 33,919		$ 32,654
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan	[2]	15		14
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan	[2]	1		6
Number Of Financing Receivables Total Past Due | loan	[2]	440		433
Total	[2]	$ 33,919		$ 32,654
Financing Receivable, 90 Days or More Past Due, Still Accruing	[2]	0		0
Consumer - Other [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[2]	259		288
Consumer - Other [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[2]	55		31
Consumer - Other [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[2]	1		8
Consumer - Other [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans	[2]	315		327
Consumer - Other [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans	[2]	$ 33,604		$ 32,327

[1] 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] Other consumer portfolio is inclusive of deposit account overdrafts recorded as loan balances. (2)The amount of net deferred costs on originated loans included in the ending balance was $6.2 million and $6.4 million at June 30, 2024 and December 31, 2023, respectively. Net unamortized discounts on acquired loans included in the ending balance were $8.4 million and $8.6 million at June 30, 2024 and December 31, 2023, respectively.