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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 11,490	$ 10,957	$ 11,232	$ 10,729	$ 10,729
Charge offs	329	55	480	373	1,273
Recoveries	60	70	94	116	276
Provision for loan losses	250	500	625	1,000	1,500
Ending balance	11,471	11,472	11,471	11,472	11,232
Ending balance specifically evaluated for impairment	1,830	2,205	1,830	2,205	2,308
Ending balance collectively evaluated for impairment	9,641	9,267	9,641	9,267	8,924
Total	1,249,132	1,224,440	1,249,132	1,224,440	1,238,283
Ending balance specifically evaluated for impairment	31,180	32,192	31,180	32,192	31,751
Ending balance collectively evaluated for impairment	1,217,952	1,192,248	1,217,952	1,192,248	1,206,532
Commercial \| Real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,632	3,732	3,567	3,872	3,872
Charge offs	53	0	53	0	168
Recoveries	5	0	13	0	52
Provision for loan losses	25	0	82	(140)	(189)
Ending balance	3,609	3,732	3,609	3,732	3,567
Ending balance specifically evaluated for impairment	196	270	196	270	260
Ending balance collectively evaluated for impairment	3,413	3,462	3,413	3,462	3,307
Total	359,581	350,114	359,581	350,114	353,243
Ending balance specifically evaluated for impairment	8,961	8,908	8,961	8,908	9,760
Ending balance collectively evaluated for impairment	350,620	341,206	350,620	341,206	343,483
Commercial \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	325	396	255	434	434
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	(16)	3	54	(35)	(179)
Ending balance	309	399	309	399	255
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	309	399	309	399	255
Total	32,785	40,308	32,785	40,308	27,304
Ending balance specifically evaluated for impairment	982	1,027	982	1,027	721
Ending balance collectively evaluated for impairment	31,803	39,281	31,803	39,281	26,583
Commercial \| Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,430	3,540	3,541	3,358	3,358
Charge offs	108	0	109	17	423
Recoveries	1	4	2	10	40
Provision for loan losses	(42)	(69)	(153)	124	566
Ending balance	3,281	3,475	3,281	3,475	3,541
Ending balance specifically evaluated for impairment	1,320	1,647	1,320	1,647	1,696
Ending balance collectively evaluated for impairment	1,961	1,828	1,961	1,828	1,845
Total	205,910	184,718	205,910	184,718	196,391
Ending balance specifically evaluated for impairment	7,582	9,439	7,582	9,439	9,259
Ending balance collectively evaluated for impairment	198,328	175,279	198,328	175,279	187,132
Municipal
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	25	21	24	20	20
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	0	0	1	1	4
Ending balance	25	21	25	21	24
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	25	21	25	21	24
Total	36,113	48,717	36,113	48,717	51,128
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	36,113	48,717	36,113	48,717	51,128
Residential \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	30	31	34	36	36
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	(7)	(2)	(11)	(7)	(2)
Ending balance	23	29	23	29	34
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	23	29	23	29	34
Total	13,239	14,583	13,239	14,583	17,743
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	13,239	14,583	13,239	14,583	17,743
Residential \| Term
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,114	1,129	1,235	1,130	1,130
Charge offs	44	15	93	96	213
Recoveries	3	38	6	42	64
Provision for loan losses	33	(14)	(42)	62	254
Ending balance	1,106	1,138	1,106	1,138	1,235
Ending balance specifically evaluated for impairment	305	286	305	286	335
Ending balance collectively evaluated for impairment	801	852	801	852	900
Total	481,349	453,588	481,349	453,588	469,145
Ending balance specifically evaluated for impairment	12,636	11,774	12,636	11,774	10,904
Ending balance collectively evaluated for impairment	468,713	441,814	468,713	441,814	458,241
Home equity line of credit
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	630	716	730	692	692
Charge offs	0	0	38	115	121
Recoveries	1	2	2	13	24
Provision for loan losses	2	(40)	(61)	88	135
Ending balance	633	678	633	678	730
Ending balance specifically evaluated for impairment	9	2	9	2	17
Ending balance collectively evaluated for impairment	624	676	624	676	713
Total	94,763	107,666	94,763	107,666	98,469
Ending balance specifically evaluated for impairment	1,019	1,028	1,019	1,028	1,092
Ending balance collectively evaluated for impairment	93,744	106,638	93,744	106,638	97,377
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	660	581	630	545	545
Charge offs	124	40	187	145	348
Recoveries	50	26	71	51	96
Provision for loan losses	63	8	135	124	337
Ending balance	649	575	649	575	630
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	649	575	649	575	630
Total	25,392	24,746	25,392	24,746	24,860
Ending balance specifically evaluated for impairment	0	16	0	16	15
Ending balance collectively evaluated for impairment	25,392	24,730	25,392	24,730	24,845
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,644	811	1,216	642	642
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	192	614	620	783	574
Ending balance	1,836	1,425	1,836	1,425	1,216
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	1,836	1,425	1,836	1,425	1,216
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.

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

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