Loans, Allowance for Loan Losses and Credit Quality (Age Analysis of Past Due Financing Receivables) (Details) $ in Thousands		Mar. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan		320	400
Number of Loans 60-89 Days | loan		53	56
Number of Loans 90 Days or More | loan		87	110
Number of Loans Total Past Due | loan		460	566
Principal Balance Total Past Due		$ 17,446	$ 46,348
Current		6,959,426	6,859,846
Total loans	[1]	6,976,872	6,906,194
Recorded Investment >90 Days and Accruing		$ 5	$ 5
Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan		2	0
Number of Loans 60-89 Days | loan		0	4
Number of Loans 90 Days or More | loan		4	11
Number of Loans Total Past Due | loan		6	15
Principal Balance Total Past Due		$ 483	$ 26,693
Current		1,150,149	1,066,936
Total loans	[1]	1,150,632	1,093,629
Recorded Investment >90 Days and Accruing		$ 0	$ 0
Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan		9	9
Number of Loans 60-89 Days | loan		0	0
Number of Loans 90 Days or More | loan		3	8
Number of Loans Total Past Due | loan		12	17
Principal Balance Total Past Due		$ 2,430	$ 3,877
Current		3,251,655	3,247,371
Total loans	[1]	3,254,085	3,251,248
Recorded Investment >90 Days and Accruing		$ 0	$ 0
Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan		1	1
Number of Loans 60-89 Days | loan		0	0
Number of Loans 90 Days or More | loan		1	1
Number of Loans Total Past Due | loan		2	2
Principal Balance Total Past Due		$ 698	$ 1,582
Current		372,819	363,583
Total loans	[1]	373,517	365,165
Recorded Investment >90 Days and Accruing		$ 0	$ 0
Small Business [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan		22	15
Number of Loans 60-89 Days | loan		23	19
Number of Loans 90 Days or More | loan		13	24
Number of Loans Total Past Due | loan		58	58
Principal Balance Total Past Due		$ 565	$ 755
Current		165,845	163,921
Total loans	[1]	166,410	164,676
Recorded Investment >90 Days and Accruing		$ 0	$ 0
Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan		12	23
Number of Loans 60-89 Days | loan		9	6
Number of Loans 90 Days or More | loan		27	25
Number of Loans Total Past Due | loan		48	54
Principal Balance Total Past Due		$ 7,550	$ 8,389
Current		927,688	914,905
Total loans	[1]	935,238	923,294
Recorded Investment >90 Days and Accruing		$ 0	$ 0
Consumer Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan		28	22
Number of Loans 60-89 Days | loan		8	12
Number of Loans 90 Days or More | loan		29	29
Number of Loans Total Past Due | loan		65	63
Principal Balance Total Past Due		$ 5,421	$ 4,849
Current		1,075,320	1,087,235
Total loans	[1]	1,080,741	1,092,084
Recorded Investment >90 Days and Accruing		$ 0	$ 0
Consumer - Other [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	[2]	246	330
Number of Loans 60-89 Days | loan	[2]	13	15
Number of Loans 90 Days or More | loan	[2]	10	12
Number of Loans Total Past Due | loan	[2]	269	357
Principal Balance Total Past Due	[2]	$ 299	$ 203
Current	[2]	15,950	15,895
Total loans	[1],[2]	16,249	16,098
Recorded Investment >90 Days and Accruing	[2]	5	5
Financing Receivables, 30 to 59 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		6,394	8,402
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		70	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		2,156	1,627
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		387	1,271
Financing Receivables, 30 to 59 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		361	506
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		1,467	3,486
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		1,711	1,331
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer - Other [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	[2]	242	181
Financing Receivables, 60 to 89 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		2,071	1,854
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		0	382
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		100	87
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		1,231	521
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		693	855
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer - Other [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	[2]	47	9
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		8,981	36,092
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		413	26,311
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		274	2,250
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		311	311
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		104	162
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		4,852	4,382
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due		3,017	2,663
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer - Other [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	[2]	$ 10	$ 13

[1] The amount of net deferred costs on originated loans included in the ending balance was $7.3 million and $7.1 million at March 31, 2019 and December 31, 2018, respectively. Net unamortized discounts on acquired loans not deemed to be purchased credit impaired ("PCI") included in the ending balance was $14.3 million and $15.2 million at March 31, 2019 and December 31, 2018, respectively.

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