Loans, Allowance for Credit Losses and Credit Quality - Financing Receivable Past Due (Details) $ in Thousands		Jun. 30, 2023 USD ($) loan		Dec. 31, 2022 USD ($) loan	Jun. 30, 2022 USD ($)
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		415		481
Total loans		$ 14,139,911	[1]	$ 13,928,675
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		34		35
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		47		46
Number Of Financing Receivables Total Past Due | loan		496		562
Total		$ 14,139,911		$ 13,928,675	$ 13,675,764
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Financing receivable, net deferred costs		6,100		5,000
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		5,016		5,934
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		30,540		6,560
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		7,064		29,426
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		42,620		41,920
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 14,097,291		$ 13,886,755
Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		1		3
Total loans		$ 1,723,219	[1]	$ 1,635,103
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		3
Number Of Financing Receivables Total Past Due | loan		5		7
Total		$ 1,723,219		$ 1,635,103	1,541,046	[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		29		49
Commercial And Industrial [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		77		175
Commercial And Industrial [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		339		23,726
Commercial And Industrial [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		445		23,950
Commercial And Industrial [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		1,722,774		$ 1,611,153
Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan				7
Total loans		$ 7,812,796	[1]	$ 7,760,230
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		3		5
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		5		3
Number Of Financing Receivables Total Past Due | loan		8		15
Total		$ 7,812,796		$ 7,760,230	7,791,757	[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				2,052
Commercial Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		29,338		4,971
Commercial Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		3,282		2,977
Commercial Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		32,620		10,000
Commercial Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 7,780,176		$ 7,750,230
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		$ 1,022,796	[1]	$ 1,154,413
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		$ 1,022,796		$ 1,154,413	1,194,577	[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		$ 1,022,796		$ 1,154,413
Small Business [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		11		12
Total loans		$ 237,092	[1]	$ 219,102
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		9		3
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		7		3
Number Of Financing Receivables Total Past Due | loan		27		18
Total		$ 237,092		$ 219,102	205,953	[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		365		111
Small Business [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		185		25
Small Business [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		111		5
Small Business [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		661		141
Small Business [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 236,431		$ 218,961
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		15		8
Total loans		$ 2,221,284	[1]	$ 2,035,524
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		5		8
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		16		16
Number Of Financing Receivables Total Past Due | loan		36		32
Total		$ 2,221,284		$ 2,035,524	1,844,057	[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		2,997		1,654
Residential Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		695		1,105
Residential Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		2,245		1,725
Residential Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		5,937		4,484
Residential Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 2,215,347		$ 2,031,040
Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		18		19
Total loans	[1]	$ 1,095,398
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		6		3
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		14		17
Number Of Financing Receivables Total Past Due | loan		38		39
Total		$ 1,095,398		$ 1,088,750	$ 1,065,510	[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		1,290		1,647
Home Equity Loan [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		182		201
Home Equity Loan [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		1,084		965
Home Equity Loan [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans		2,556		2,813
Home Equity Loan [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans		$ 1,092,842		$ 1,085,937
Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan	[2]	370		432
Total loans		$ 27,326		$ 35,553
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan	[2]	9		15
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan	[2]	3		4
Number Of Financing Receivables Total Past Due | loan	[2]	382		451
Total	[2]	$ 27,326		$ 35,553
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]	335		421
Consumer - Other [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[2]	63		83
Consumer - Other [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans	[2]	3		28
Consumer - Other [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Total loans	[2]	401		532
Consumer - Other [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total loans	[2]	$ 26,925		$ 35,021

[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 $6.1 million and $5.0 million at June 30, 2023 and December 31, 2022, respectively.