Loans, Allowance for Credit Losses and Credit Quality Financing Receivable Past Due (Details) $ in Thousands		Sep. 30, 2021 USD ($) loan		Dec. 31, 2020 USD ($) loan	Sep. 30, 2020 USD ($)
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		268		301
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0		$ 1
Loans and Leases Receivable, Gross		$ 8,808,013	[1]	$ 9,392,866	$ 9,405,193
Number Of Financing Receivables Total Past Due | loan		350		408
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		23		25
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		59		82
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 8,353		$ 4,168
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		1,707		9,450
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		8,309		7,778
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		8,789,644		9,371,470
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 18,369		$ 21,396
Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		2		2
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0		$ 0
Loans and Leases Receivable, Gross		$ 1,640,709	[1]	$ 2,103,152	2,062,345	[1]
Number Of Financing Receivables Total Past Due | loan		3		11
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		1		1
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		0		8
Financing Receivable, before Allowance for Credit Loss		$ 1,640,709		$ 2,103,152
Commercial And Industrial [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		343		318
Commercial And Industrial [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		87		672
Commercial And Industrial [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		785
Commercial And Industrial [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		1,640,279		2,101,377
Commercial And Industrial [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 430		$ 1,775
Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		6		3
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0		$ 0
Loans and Leases Receivable, Gross		$ 4,221,259	[1]	$ 4,173,927	4,125,464	[1]
Number Of Financing Receivables Total Past Due | loan		12		7
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		1		0
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		5		4
Financing Receivable, before Allowance for Credit Loss		$ 4,221,259		$ 4,173,927
Commercial Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		5,142		409
Commercial Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		487		0
Commercial Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		3,674		515
Commercial Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		4,211,956		4,173,003
Commercial Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 9,303		$ 924
Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		0		0
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0		$ 0
Loans and Leases Receivable, Gross		$ 515,415	[1]	$ 553,929	573,334	[1]
Number Of Financing Receivables Total Past Due | loan		0		2
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		0		2
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		0		0
Financing Receivable, before Allowance for Credit Loss		$ 515,415		$ 553,929
Construction Loans [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		0
Construction Loans [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		2,794
Construction Loans [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		0
Construction Loans [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		515,415		551,135
Construction Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 0		$ 2,794
Small Business [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		8		14
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0		$ 0
Loans and Leases Receivable, Gross		$ 184,138	[1]	$ 175,023	167,632	[1]
Number Of Financing Receivables Total Past Due | loan		15		24
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		2		6
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		5		4
Financing Receivable, before Allowance for Credit Loss		$ 184,138		$ 175,023
Small Business [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		243		421
Small Business [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		35		273
Small Business [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		27		59
Small Business [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		183,833		174,270
Small Business [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 305		$ 753
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		13		12
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0		$ 0
Loans and Leases Receivable, Gross		$ 1,222,849	[1]	$ 1,296,183	$ 1,352,305	[1]
Number Of Financing Receivables Total Past Due | loan		37		47
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		2		8
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		22		27
Financing Receivable, before Allowance for Credit Loss		$ 1,222,849		$ 1,296,183
Residential Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,037		2,150
Residential Real Estate [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		848		5,507
Residential Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,822		3,648
Residential Real Estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		1,217,142		1,284,878
Residential Real Estate [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 5,707		$ 11,305
Home Equity Line of Credit [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		9		10
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0		$ 0
Loans and Leases Receivable, Gross		$ 1,000,468		$ 1,068,790
Number Of Financing Receivables Total Past Due | loan		38		48
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		5		5
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		24		33
Home Equity Line of Credit [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 479		$ 733
Home Equity Line of Credit [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		218		203
Home Equity Line of Credit [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		1,784		2,633
Home Equity Line of Credit [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		997,987		1,065,221
Home Equity Line of Credit [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 2,481		$ 3,569
Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan	[2]	230		260
Financing Receivable, 90 Days or More Past Due, Still Accruing	[2]	$ 0		$ 1
Loans and Leases Receivable, Gross	[2]	$ 23,175		$ 21,862
Number Of Financing Receivables Total Past Due | loan	[2]	245		269
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan	[2]	12		3
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan	[2]	3		6
Financing Receivable, before Allowance for Credit Loss		$ 23,175		$ 21,862
Consumer - Other [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	[2]	109		137
Consumer - Other [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	[2]	32		1
Consumer - Other [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	[2]	2		138
Consumer - Other [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	[2]	23,032		21,586
Consumer - Other [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	[2]	$ 143		$ 276

[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.