Loans, Allowance for Loan Losses and Credit Quality (Int Inc. Recognized on Impaired Loans by Portfolio) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Interest income recognized on impaired loans
Average Recorded Investment	$ 54,648	$ 68,720	$ 56,449	$ 69,656
Interest Income Recognized	341	413	683	823
WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	44,717	56,238	46,427	57,102
Interest Income Recognized	240	300	483	598
WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	9,931	12,482	10,022	12,554
Interest Income Recognized	101	113	200	225
Commercial and Industrial [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	27,406	32,557	28,971	33,198
Interest Income Recognized	34	34	70	68
Commercial and Industrial [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	268	225	270	226
Interest Income Recognized	3	2	6	5
Commercial Real Estate [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	7,496	13,018	7,582	13,131
Interest Income Recognized	92	148	186	295
Commercial Real Estate [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	1,662	2,165	1,672	2,172
Interest Income Recognized	24	24	49	48
Small Business [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	309	672	319	703
Interest Income Recognized	2	3	6	8
Small Business [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	190	163	192	169
Interest Income Recognized	2	3	5	6
Residential Real Estate [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	4,713	4,825	4,727	4,842
Interest Income Recognized	58	60	113	119
Residential Real Estate [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	6,707	8,003	6,775	8,045
Interest Income Recognized	59	68	116	136
Consumer Home Equity [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	4,751	5,100	4,783	5,160
Interest Income Recognized	53	54	107	106
Consumer Home Equity [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	972	1,732	978	1,744
Interest Income Recognized	11	15	22	27
Consumer - Other [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	42	66	45	68
Interest Income Recognized	1	1	1	2
Consumer - Other [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	132	194	135	198
Interest Income Recognized	$ 2	$ 1	$ 2	$ 3

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

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-Publisher FASB
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-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

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