Impaired Loan Information by Portfolio (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 980	$ 1,079	$ 1,342
Related Allowance	980	1,079	1,342
Recorded Investment	49,628	59,060	72,801
Unpaid Principal Balance	68,140	68,514	79,276
Average Recorded Investment	59,682	63,522	76,180
Interest Income Recognized	1,537	1,554	2,026
Commercial and Industrial [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	126	7	10
Commercial Real Estate [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	48	37	42
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	8	1	1
Residential Real Estate [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	637	862	1,007
Home Equity [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	156	164	265
Consumer Portfolio Segment [Member]
Impaired loans by loan portfolio
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	5	8	17
With No Related Allowance Recorded [Member]
Impaired loans by loan portfolio
Recorded Investment	39,242	47,900	57,373
Unpaid Principal Balance	56,605	56,125	62,867
Average Recorded Investment	49,077	51,970	60,380
Interest Income Recognized	1,090	1,111	1,449
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] \| Commercial and Industrial [Member]
Impaired loans by loan portfolio
Recorded Investment	23,786	28,459	34,267
Unpaid Principal Balance	34,970	35,913	38,329
Average Recorded Investment	27,056	31,117	36,631
Interest Income Recognized	136	142	446
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] \| Commercial Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	6,213	9,552	13,245
Unpaid Principal Balance	12,101	9,832	14,374
Average Recorded Investment	12,595	10,561	13,683
Interest Income Recognized	523	519	559
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] \| Small Business [Member]
Impaired loans by loan portfolio
Recorded Investment	469	358	556
Unpaid Principal Balance	484	439	619
Average Recorded Investment	471	401	569
Interest Income Recognized	22	14	21
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] \| Residential Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	4,976	4,518	4,264
Unpaid Principal Balance	5,123	4,686	4,397
Average Recorded Investment	5,045	4,597	4,332
Interest Income Recognized	222	212	218
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] \| Home Equity [Member]
Impaired loans by loan portfolio
Recorded Investment	3,764	4,957	4,950
Unpaid Principal Balance	3,893	5,199	5,056
Average Recorded Investment	3,869	5,230	5,063
Interest Income Recognized	184	220	198
Related Allowance	0	0	0
With No Related Allowance Recorded [Member] \| Consumer Portfolio Segment [Member]
Impaired loans by loan portfolio
Recorded Investment	34	56	91
Unpaid Principal Balance	34	56	92
Average Recorded Investment	41	64	102
Interest Income Recognized	3	4	7
Related Allowance	0	0	0
With Allowance Recorded [Member]
Impaired loans by loan portfolio
Recorded Investment	10,386	11,160	15,428
Unpaid Principal Balance	11,535	12,389	16,409
Average Recorded Investment	10,605	11,552	15,800
Interest Income Recognized	447	443	577
With Allowance Recorded [Member] \| Commercial and Industrial [Member]
Impaired loans by loan portfolio
Recorded Investment	670	370	376
Unpaid Principal Balance	670	370	376
Average Recorded Investment	718	385	391
Interest Income Recognized	29	19	19
With Allowance Recorded [Member] \| Commercial Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	2,124	1,287	3,393
Unpaid Principal Balance	2,124	1,287	3,399
Average Recorded Investment	2,176	1,311	3,447
Interest Income Recognized	122	74	198
With Allowance Recorded [Member] \| Small Business [Member]
Impaired loans by loan portfolio
Recorded Investment	68	183	147
Unpaid Principal Balance	105	223	153
Average Recorded Investment	74	225	238
Interest Income Recognized	2	13	14
With Allowance Recorded [Member] \| Residential Real Estate [Member]
Impaired loans by loan portfolio
Recorded Investment	6,252	8,188	9,420
Unpaid Principal Balance	7,163	9,217	10,154
Average Recorded Investment	6,326	8,459	9,575
Interest Income Recognized	239	289	284
With Allowance Recorded [Member] \| Home Equity [Member]
Impaired loans by loan portfolio
Recorded Investment	1,184	991	1,876
Unpaid Principal Balance	1,382	1,149	2,110
Average Recorded Investment	1,214	1,018	1,916
Interest Income Recognized	52	43	55
With Allowance Recorded [Member] \| Consumer Portfolio Segment [Member]
Impaired loans by loan portfolio
Recorded Investment	88	141	216
Unpaid Principal Balance	91	143	217
Average Recorded Investment	97	154	233
Interest Income Recognized	$ 3	$ 5	$ 7

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 50
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