Allowance for Loan Losses - Allowance for Loan Loss Activity by Class (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 10,367	$ 10,219	$ 10,138	$ 9,916	$ 9,916
Charge offs	290	476	617	666	1,721
Recoveries	34	80	90	198	343
Provision for loan losses	500	375	1,000	750	1,600
Ending balance	10,611	10,198	10,611	10,198	10,138
Ending balance specifically evaluated for impairment	594	1,029	594	1,029	974
Ending balance collectively evaluated for impairment	10,017	9,169	10,017	9,169	9,164
Total	1,120,665	1,038,213	1,120,665	1,038,213	1,071,526
Ending balance specifically evaluated for impairment	26,644	28,193	26,644	28,193	27,583
Ending balance collectively evaluated for impairment	1,094,021	1,010,020	1,094,021	1,010,020	1,043,943
Commercial \| Real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,015	3,524	3,988	3,120	3,120
Charge offs	141	33	305	33	294
Recoveries	0	0	0	0	0
Provision for loan losses	122	464	313	868	1,162
Ending balance	3,996	3,955	3,996	3,955	3,988
Ending balance specifically evaluated for impairment	221	369	221	369	505
Ending balance collectively evaluated for impairment	3,775	3,586	3,775	3,586	3,483
Total	306,490	303,312	306,490	303,312	302,506
Ending balance specifically evaluated for impairment	9,853	10,685	9,853	10,685	10,021
Ending balance collectively evaluated for impairment	296,637	292,627	296,637	292,627	292,485
Commercial \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	441	345	396	580	580
Charge offs	0	0	0	58	75
Recoveries	0	0	0	0	8
Provision for loan losses	76	(27)	121	(204)	(117)
Ending balance	517	318	517	318	396
Ending balance specifically evaluated for impairment	103	97	103	97	100
Ending balance collectively evaluated for impairment	414	221	414	221	296
Total	33,605	18,439	33,605	18,439	25,406
Ending balance specifically evaluated for impairment	763	834	763	834	763
Ending balance collectively evaluated for impairment	32,842	17,605	32,842	17,605	24,643
Commercial \| Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,925	1,676	1,780	1,452	1,452
Charge offs	58	30	58	30	376
Recoveries	7	36	18	56	129
Provision for loan losses	297	96	431	300	575
Ending balance	2,171	1,778	2,171	1,778	1,780
Ending balance specifically evaluated for impairment	36	158	36	158	39
Ending balance collectively evaluated for impairment	2,135	1,620	2,135	1,620	1,741
Total	173,691	136,651	173,691	136,651	150,769
Ending balance specifically evaluated for impairment	1,633	1,479	1,633	1,479	1,743
Ending balance collectively evaluated for impairment	172,058	135,172	172,058	135,172	149,026
Municipal
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	18	17	18	17	17
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	1	0	1	0	1
Ending balance	19	17	19	17	18
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	19	17	19	17	18
Total	28,695	25,531	28,695	25,531	27,056
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	28,695	25,531	28,695	25,531	27,056
Residential \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	24	33	44	24	24
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	2	1	(18)	10	20
Ending balance	26	34	26	34	44
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	26	34	26	34	44
Total	15,056	13,403	15,056	13,403	18,303
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	15,056	13,403	15,056	13,403	18,303
Residential \| Term
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	969	1,474	1,288	1,391	1,391
Charge offs	17	246	70	266	379
Recoveries	5	9	19	74	93
Provision for loan losses	42	128	(238)	166	183
Ending balance	999	1,365	999	1,365	1,288
Ending balance specifically evaluated for impairment	209	326	209	326	304
Ending balance collectively evaluated for impairment	790	1,039	790	1,039	984
Total	427,171	403,461	427,171	403,461	411,469
Ending balance specifically evaluated for impairment	12,990	14,105	12,990	14,105	13,669
Ending balance collectively evaluated for impairment	414,181	389,356	414,181	389,356	397,800
Home equity line of credit
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	811	905	807	893	893
Charge offs	21	73	28	122	147
Recoveries	3	1	3	2	5
Provision for loan losses	(109)	47	(98)	107	56
Ending balance	684	880	684	880	807
Ending balance specifically evaluated for impairment	25	28	25	28	26
Ending balance collectively evaluated for impairment	659	852	659	852	781
Total	110,328	112,536	110,328	112,536	110,907
Ending balance specifically evaluated for impairment	1,405	975	1,405	975	1,387
Ending balance collectively evaluated for impairment	108,923	111,561	108,923	111,561	109,520
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	573	654	559	566	566
Charge offs	53	94	156	157	450
Recoveries	19	34	50	66	108
Provision for loan losses	(10)	41	76	160	335
Ending balance	529	635	529	635	559
Ending balance specifically evaluated for impairment	0	51	0	51	0
Ending balance collectively evaluated for impairment	529	584	529	584	559
Total	25,629	24,880	25,629	24,880	25,110
Ending balance specifically evaluated for impairment	0	115	0	115	0
Ending balance collectively evaluated for impairment	25,629	24,765	25,629	24,765	25,110
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,591	1,591	1,258	1,873	1,873
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	79	(375)	412	(657)	(615)
Ending balance	1,670	1,216	1,670	1,216	1,258
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	1,670	1,216	1,670	1,216	1,258
Total	0	0	0	0	0
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	$ 0	$ 0	$ 0	$ 0	$ 0

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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

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The balance of financing receivables that were collectively evaluated for impairment.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

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