Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 15,767	$ 15,442
Provision (reversal)	0	500
Charge-offs	(5)	(293)
Recoveries	59	118
Ending balance	15,821	15,767
Ending ALLL related to loans collectively evaluated for impairment	15,043	15,254
Ending ALLL related to loans individually evaluated for impairment	778	513
Ending ALLL related to purchased credit-impaired loans	15,821	15,767
Recorded Investment:
Collectively evaluated for impairment	1,746,714	1,659,972
Individually evaluated for impairment	15,038	16,926
Total loans	$ 1,763,864	$ 1,679,013
Ratio of allowance for loan losses to total loans	0.90%	0.94%
Allowance for loan losses to non-accrual loans	2270.00%	3883.00%
Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	2,112	2,115
Commercial \| Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,654	3,248
Provision (reversal)	(1,232)	584
Charge-offs	(3)	(289)
Recoveries	17	111
Ending balance	2,436	3,654
Ending ALLL related to loans collectively evaluated for impairment	1,970	3,604
Ending ALLL related to loans individually evaluated for impairment	466	50
Ending ALLL related to purchased credit-impaired loans	2,436	3,654
Recorded Investment:
Collectively evaluated for impairment	228,883	233,605
Individually evaluated for impairment	1,825	2,165
Total loans	$ 230,739	$ 235,835
Ratio of allowance for loan losses to total loans	1.06%	1.55%
Commercial \| Commercial and industrial \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	31	65
Commercial real estate \| Commercial real estate, owner-occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,294	1,753
Provision (reversal)	113	541
Charge-offs	0	0
Recoveries	0	0
Ending balance	2,407	2,294
Ending ALLL related to loans collectively evaluated for impairment	2,218	2,106
Ending ALLL related to loans individually evaluated for impairment	189	188
Ending ALLL related to purchased credit-impaired loans	2,407	2,294
Recorded Investment:
Collectively evaluated for impairment	305,097	292,798
Individually evaluated for impairment	6,993	6,999
Total loans	$ 313,277	$ 300,963
Ratio of allowance for loan losses to total loans	0.77%	0.76%
Commercial real estate \| Commercial real estate, owner-occupied \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	1,187	1,166
Commercial real estate \| Commercial real estate, investor
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,475	6,320
Provision (reversal)	1,228	155
Charge-offs	0	0
Recoveries	0	0
Ending balance	7,703	6,475
Ending ALLL related to loans collectively evaluated for impairment	7,658	6,316
Ending ALLL related to loans individually evaluated for impairment	45	159
Ending ALLL related to purchased credit-impaired loans	7,703	6,475
Recorded Investment:
Collectively evaluated for impairment	870,778	820,023
Individually evaluated for impairment	1,821	2,171
Total loans	$ 873,410	$ 822,984
Ratio of allowance for loan losses to total loans	0.88%	0.79%
Commercial real estate \| Commercial real estate, investor \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	811	790
Commercial real estate \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	681	781
Provision (reversal)	75	(100)
Charge-offs	0	0
Recoveries	0	0
Ending balance	756	681
Ending ALLL related to loans collectively evaluated for impairment	756	674
Ending ALLL related to loans individually evaluated for impairment	0	7
Ending ALLL related to purchased credit-impaired loans	756	681
Recorded Investment:
Collectively evaluated for impairment	73,735	60,859
Individually evaluated for impairment	2,688	2,969
Total loans	$ 76,423	$ 63,828
Ratio of allowance for loan losses to total loans	0.99%	1.07%
Commercial real estate \| Construction \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	0	0
Residential loans \| Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,031	973
Provision (reversal)	(116)	58
Charge-offs	0	0
Recoveries	0	0
Ending balance	915	1,031
Ending ALLL related to loans collectively evaluated for impairment	910	1,025
Ending ALLL related to loans individually evaluated for impairment	5	6
Ending ALLL related to purchased credit-impaired loans	915	1,031
Recorded Investment:
Collectively evaluated for impairment	124,049	131,620
Individually evaluated for impairment	564	753
Total loans	$ 124,696	$ 132,467
Ratio of allowance for loan losses to total loans	0.73%	0.78%
Allowance for loan losses to non-accrual loans	292.00%	254.00%
Residential loans \| Home equity \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	83	94
Residential loans \| Other residential
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	536	454
Provision (reversal)	264	82
Charge-offs	0	0
Recoveries	0	0
Ending balance	800	536
Ending ALLL related to loans collectively evaluated for impairment	800	535
Ending ALLL related to loans individually evaluated for impairment	0	1
Ending ALLL related to purchased credit-impaired loans	800	536
Recorded Investment:
Collectively evaluated for impairment	117,385	94,378
Individually evaluated for impairment	462	1,148
Total loans	$ 117,847	$ 95,526
Ratio of allowance for loan losses to total loans	0.68%	0.56%
Residential loans \| Other residential \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	0	0
Consumer loans \| Installment and other consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	378	372
Provision (reversal)	(108)	3
Charge-offs	(2)	(4)
Recoveries	42	7
Ending balance	310	378
Ending ALLL related to loans collectively evaluated for impairment	237	276
Ending ALLL related to loans individually evaluated for impairment	73	102
Ending ALLL related to purchased credit-impaired loans	310	378
Recorded Investment:
Collectively evaluated for impairment	26,787	26,689
Individually evaluated for impairment	685	721
Total loans	$ 27,472	$ 27,410
Ratio of allowance for loan losses to total loans	1.13%	1.38%
Consumer loans \| Installment and other consumer \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	$ 0	$ 0
Recorded Investment:
Purchased credit-impaired	0	0
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	718	1,541
Provision (reversal)	(224)	(823)
Charge-offs	0	0
Recoveries	0	0
Ending balance	494	718
Ending ALLL related to loans collectively evaluated for impairment	494	718
Ending ALLL related to loans individually evaluated for impairment	0	0
Ending ALLL related to purchased credit-impaired loans	494	718
Recorded Investment:
Collectively evaluated for impairment	0	0
Individually evaluated for impairment	0	0
Total loans	0	0
Unallocated \| Purchased credit-impaired
Allowance for Loan and Lease Losses [Roll Forward]
Ending ALLL related to purchased credit-impaired loans	0	0
Recorded Investment:
Purchased credit-impaired	$ 0	$ 0

Allowance as percentage of non-accrual loans.

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Allowance as percentage of total loans.

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

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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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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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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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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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