Loans, Allowance for Loan Losses and Credit Quality (Impaired Loans by Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 1,257	$ 1,342	$ 5,055
Related Allowance	1,257	1,342
Impaired Financing Receivable, Recorded Investment, Total	70,923	72,801
Impaired Financing Receivable, Unpaid Principal Balance	79,285	79,276
WITH NO RELATED ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	57,919	57,373
Unpaid Principal Balance	65,286	62,867
Related Allowance	0	0
WITH AN ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	13,004	15,428
Unpaid Principal Balance	13,999	16,409
Commercial and Industrial [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	9	10	3,558
Commercial and Industrial [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	32,878	34,267
Unpaid Principal Balance	38,785	38,329
Related Allowance	0	0
Commercial and Industrial [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	226	376
Unpaid Principal Balance	226	376
Commercial Real Estate [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	37	42	173
Commercial Real Estate [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	14,747	13,245
Unpaid Principal Balance	15,894	14,374
Related Allowance	0	0
Commercial Real Estate [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	1,723	3,393
Unpaid Principal Balance	1,723	3,399
Construction Loans [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Small Business [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	3	1	2
Small Business [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	727	556
Unpaid Principal Balance	797	619
Related Allowance	0	0
Small Business [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	126	147
Unpaid Principal Balance	132	153
Residential Real Estate [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	944	1,007	1,066
Residential Real Estate [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	4,234	4,264
Unpaid Principal Balance	4,367	4,397
Related Allowance	0	0
Residential Real Estate [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	9,044	9,420
Unpaid Principal Balance	9,790	10,154
Consumer Home Equity [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	248	265	235
Consumer Home Equity [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	5,248	4,950
Unpaid Principal Balance	5,357	5,056
Related Allowance	0	0
Consumer Home Equity [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	1,678	1,876
Unpaid Principal Balance	1,919	2,110
Consumer - Other [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	16	17	$ 21
Consumer - Other [Member] \| WITH NO RELATED ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	85	91
Unpaid Principal Balance	86	92
Related Allowance	0	0
Consumer - Other [Member] \| WITH AN ALLOWANCE RECORDED: [Member]
Impaired loans by loan portfolio
Recorded Investment	207	216
Unpaid Principal Balance	$ 209	$ 217

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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- Definition

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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