Loans, Allowance for Credit Losses and Credit Quality Financing Receivable Past Due (Details) $ in Thousands		Mar. 31, 2021 USD ($) loan	Dec. 31, 2020 USD ($) loan	Mar. 31, 2020 USD ($)
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		226	301
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 1	$ 1
Financing Receivable, Past Due		11,024	21,396
Financing Receivable, Not Past Due		9,235,667	9,371,470
Loans and Leases Receivable, Gross		$ 9,246,691	$ 9,392,866	$ 8,916,430
Number Of Financing Receivables Total Past Due | loan		312	408
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		7	25
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		79	82
Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		6	2
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0	$ 0
Financing Receivable, Past Due		651	1,775
Financing Receivable, Not Past Due		2,086,020	2,101,377
Loans and Leases Receivable, Gross		$ 2,086,671	$ 2,103,152	1,448,224
Number Of Financing Receivables Total Past Due | loan		16	11
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		0	1
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		10	8
Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		3	3
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0	$ 0
Financing Receivable, Past Due		1,399	924
Financing Receivable, Not Past Due		4,176,218	4,173,003
Loans and Leases Receivable, Gross		$ 4,177,617	$ 4,173,927	4,061,347
Number Of Financing Receivables Total Past Due | loan		7	7
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		4	4
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
Financing Receivable, Past Due		0	2,794
Financing Receivable, Not Past Due		516,362	551,135
Loans and Leases Receivable, Gross		$ 516,362	$ 553,929	527,138
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
Small Business [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		5	14
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0	$ 0
Financing Receivable, Past Due		94	753
Financing Receivable, Not Past Due		174,117	174,270
Loans and Leases Receivable, Gross		$ 174,211	$ 175,023	177,820
Number Of Financing Receivables Total Past Due | loan		9	24
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		1	6
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		3	4
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		9	12
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0	$ 0
Financing Receivable, Past Due		5,853	11,305
Financing Receivable, Not Past Due		1,235,936	1,284,878
Loans and Leases Receivable, Gross		$ 1,241,789	$ 1,296,183	$ 1,528,416
Number Of Financing Receivables Total Past Due | loan		40	47
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		3	8
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		28	27
Home Equity Line of Credit [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan		7	10
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0	$ 0
Financing Receivable, Past Due		2,729	3,569
Financing Receivable, Not Past Due		1,025,766	1,065,221
Loans and Leases Receivable, Gross		$ 1,028,495	$ 1,068,790
Number Of Financing Receivables Total Past Due | loan		36	48
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan		2	5
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan		27	33
Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Number Of Financing Receivables Thirty To Fifty Nine Days Past Due | loan	[1]	196	260
Financing Receivable, 90 Days or More Past Due, Still Accruing	[1]	$ 1	$ 1
Financing Receivable, Past Due	[1]	298	276
Financing Receivable, Not Past Due	[1]	21,248	21,586
Loans and Leases Receivable, Gross	[1]	$ 21,546	$ 21,862
Number Of Financing Receivables Total Past Due | loan	[1]	204	269
Number of Financing Receivables Sixty to Eighty Nine Days Past Due | loan	[1]	1	3
Number Of Financing Receivables Equal To Greater Than Ninety Days | loan	[1]	7	6
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		$ 854	$ 9,450
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		0	672
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		0	2,794
Financial Asset, 60 to 89 Days Past Due [Member] | Small Business [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		2	273
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		764	5,507
Financial Asset, 60 to 89 Days Past Due [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		87	203
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	[1]	1	1
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		6,872	7,778
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		141	785
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		511	515
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Small Business [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		36	59
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		3,837	3,648
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		2,217	2,633
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	[1]	130	138
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		3,298	4,168
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		510	318
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		888	409
Financial Asset, 30 to 59 Days Past Due [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Small Business [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		56	421
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		1,252	2,150
Financial Asset, 30 to 59 Days Past Due [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due		425	733
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer - Other [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	[1]	$ 167	$ 137

[1] Other consumer portfolio is inclusive of deposit account overdrafts recorded as loan balances.