Imparied Loan Information by Portfolio (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 5,214	$ 1,930	$ 2,416
Related Allowance	5,214	1,930	2,416
Recorded Investment	77,297	51,410	58,035
Unpaid Principal Balance	81,071	54,822	61,887
Average Recorded Investment	77,209	51,678	62,202
Interest Income Recognized	2,700	1,993	3,242
Commercial and Industrial [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	3,661	183	412
Commercial Real Estate [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	196	204	197
Construction Loans [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0	0
Small Business [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	8	4	7
Residential Real Estate [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	1,086	1,278	1,500
Home Equity [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	242	238	262
Consumer Portfolio Segment [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	21	23	38
With No Related Allowance Recorded [Member]
Impaired loans by loan portfolio
Recorded Investment	49,745	24,403	26,936
Unpaid Principal Balance	52,377	26,276	28,535
Average Recorded Investment	48,814	24,774	29,464
Interest Income Recognized	1,764	835	1,665
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] | Commercial and Industrial [Member]
Impaired loans by loan portfolio
Recorded Investment	28,776	2,613	3,005
Unpaid Principal Balance	29,772	3,002	3,278
Average Recorded Investment	26,472	3,024	4,557
Interest Income Recognized	927	71	258
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] | Commercial Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	11,628	12,008	15,982
Unpaid Principal Balance	12,891	13,128	17,164
Average Recorded Investment	12,744	11,676	16,703
Interest Income Recognized	437	375	1,025
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] | Construction Loans [Member]
Impaired loans by loan portfolio
Recorded Investment		304	311
Unpaid Principal Balance		305	311
Average Recorded Investment		308	311
Interest Income Recognized		0	13
Related Allowance		0	0
With No Related Allowance Recorded [Member] | Small Business [Member]
Impaired loans by loan portfolio
Recorded Investment	494	527	692
Unpaid Principal Balance	569	618	718
Average Recorded Investment	534	584	772
Interest Income Recognized	20	22	45
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] | Residential Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	4,216	3,874	2,439
Unpaid Principal Balance	4,427	4,033	2,502
Average Recorded Investment	4,302	3,958	2,493
Interest Income Recognized	185	157	102
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] | Home Equity [Member]
Impaired loans by loan portfolio
Recorded Investment	4,485	4,893	4,169
Unpaid Principal Balance	4,572	5,005	4,221
Average Recorded Investment	4,602	5,023	4,264
Interest Income Recognized	184	195	198
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] | Consumer Portfolio Segment [Member]
Impaired loans by loan portfolio
Recorded Investment	146	184	338
Unpaid Principal Balance	146	185	341
Average Recorded Investment	160	201	364
Interest Income Recognized	11	15	24
Related Allowance	0	0	0
With Allowance Recorded [Member]
Impaired loans by loan portfolio
Recorded Investment	27,552	27,007	31,099
Unpaid Principal Balance	28,694	28,546	33,352
Average Recorded Investment	28,395	26,904	32,738
Interest Income Recognized	936	1,158	1,577
With Allowance Recorded [Member] | Commercial and Industrial [Member]
Impaired loans by loan portfolio
Recorded Investment	10,402	2,534	1,649
Unpaid Principal Balance	10,440	2,648	1,859
Average Recorded Investment	10,760	2,848	2,032
Interest Income Recognized	325	48	98
With Allowance Recorded [Member] | Commercial Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	5,185	10,978	14,747
Unpaid Principal Balance	5,533	11,047	15,514
Average Recorded Investment	5,491	10,789	15,650
Interest Income Recognized	200	592	842
With Allowance Recorded [Member] | Small Business [Member]
Impaired loans by loan portfolio
Recorded Investment	377	494	396
Unpaid Principal Balance	392	523	458
Average Recorded Investment	408	535	456
Interest Income Recognized	21	30	32
With Allowance Recorded [Member] | Residential Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	9,959	11,531	12,616
Unpaid Principal Balance	10,530	12,652	13,727
Average Recorded Investment	10,065	11,669	12,817
Interest Income Recognized	332	460	537
With Allowance Recorded [Member] | Home Equity [Member]
Impaired loans by loan portfolio
Recorded Investment	1,378	1,096	1,161
Unpaid Principal Balance	1,547	1,287	1,264
Average Recorded Investment	1,403	655	1,203
Interest Income Recognized	50	14	46
With Allowance Recorded [Member] | Consumer Portfolio Segment [Member]
Impaired loans by loan portfolio
Recorded Investment	251	374	530
Unpaid Principal Balance	252	389	530
Average Recorded Investment	268	408	580
Interest Income Recognized	$ 8	$ 14	$ 22