Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Allowance for loan losses:
Beginning balance	$ 15,232	$ 15,087	$ 15,442	$ 14,999
(Reversal of) provision for loan losses	0	(1,550)	0	(1,550)
Charge-offs	(6)	0	(292)	(13)
Recoveries	22	2,176	98	2,277
Ending balance	15,248	15,713	15,248	15,713
Ending ALLL related to loans collectively evaluated for impairment	14,662		14,662		$ 14,451
Ending ALLL related to loans individually evaluated for impairment	586		586		991
Ending ALLL	15,248		15,248		15,442
Collectively evaluated for impairment	1,504,475		1,504,475		1,465,383
Individually evaluated for impairment	17,700		17,700		18,313
Total loans	$ 1,524,447		$ 1,524,447		$ 1,486,616
Ratio of allowance for loan losses to total loans	1.00%		1.00%		1.04%
Allowance for loan losses to non-accrual loans	1159.00%		1159.00%		10650.00%
Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	2,272		2,272		2,920
Commercial loans \| Commercial and industrial
Allowance for loan losses:
Beginning balance	3,932	2,637	3,248	3,023
(Reversal of) provision for loan losses	612	828	1,509	388
Charge-offs	(5)	0	(289)	(9)
Recoveries	21	29	92	92
Ending balance	4,560	3,494	4,560	3,494
Ending ALLL related to loans collectively evaluated for impairment	4,525		4,525		2,963
Ending ALLL related to loans individually evaluated for impairment	35		35		285
Ending ALLL	4,560		4,560		3,248
Collectively evaluated for impairment	216,594		216,594		216,368
Individually evaluated for impairment	2,050		2,050		2,207
Total loans	$ 218,681		$ 218,681		$ 218,615
Ratio of allowance for loan losses to total loans	2.09%		2.09%		1.49%
Commercial loans \| Commercial and industrial \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	37		37		40
Commercial real estate loans \| Commercial real estate, owner-occupied
Allowance for loan losses:
Beginning balance	2,082	1,631	1,753	2,249
(Reversal of) provision for loan losses	(56)	(10)	273	(628)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	2,026	1,621	2,026	1,621
Ending ALLL related to loans collectively evaluated for impairment	1,942		1,942		1,590
Ending ALLL related to loans individually evaluated for impairment	84		84		163
Ending ALLL	2,026		2,026		1,753
Collectively evaluated for impairment	256,593		256,593		239,648
Individually evaluated for impairment	6,999		6,999		6,993
Total loans	$ 264,732		$ 264,732		$ 247,713
Ratio of allowance for loan losses to total loans	0.77%		0.77%		0.71%
Commercial real estate loans \| Commercial real estate, owner-occupied \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	1,140		1,140		1,072
Commercial real estate loans \| Commercial real estate, investor
Allowance for loan losses:
Beginning balance	6,065	6,595	6,320	6,178
(Reversal of) provision for loan losses	33	(2,416)	(222)	(2,009)
Charge-offs	0	0	0	0
Recoveries	0	2,146	0	2,156
Ending balance	6,098	6,325	6,098	6,325
Ending ALLL related to loans collectively evaluated for impairment	5,729		5,729		5,945
Ending ALLL related to loans individually evaluated for impairment	369		369		375
Ending ALLL	6,098		6,098		6,320
Collectively evaluated for impairment	717,361		717,361		720,266
Individually evaluated for impairment	3,217		3,217		2,256
Total loans	$ 721,576		$ 721,576		$ 724,228
Ratio of allowance for loan losses to total loans	0.85%		0.85%		0.87%
Allowance for loan losses to non-accrual loans	596.00%		596.00%
Commercial real estate loans \| Commercial real estate, investor \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	998		998		1,706
Commercial real estate loans \| Construction
Allowance for loan losses:
Beginning balance	411	831	781	724
(Reversal of) provision for loan losses	217	105	(153)	212
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	628	936	628	936
Ending ALLL related to loans collectively evaluated for impairment	623		623		773
Ending ALLL related to loans individually evaluated for impairment	5		5		8
Ending ALLL	628		628		781
Collectively evaluated for impairment	73,210		73,210		71,564
Individually evaluated for impairment	2,969		2,969		3,245
Total loans	$ 76,179		$ 76,179		$ 74,809
Ratio of allowance for loan losses to total loans	0.82%		0.82%		1.04%
Commercial real estate loans \| Construction \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	0		0		0
Residential loans \| Home equity
Allowance for loan losses:
Beginning balance	981	1,076	973	910
(Reversal of) provision for loan losses	21	(125)	29	40
Charge-offs	0	0	0	0
Recoveries	0	1	0	2
Ending balance	1,002	952	1,002	952
Ending ALLL related to loans collectively evaluated for impairment	996		996		966
Ending ALLL related to loans individually evaluated for impairment	6		6		7
Ending ALLL	1,002		1,002		973
Collectively evaluated for impairment	120,629		120,629		116,390
Individually evaluated for impairment	640		640		715
Total loans	$ 121,366		$ 121,366		$ 117,207
Ratio of allowance for loan losses to total loans	0.83%		0.83%		0.83%
Allowance for loan losses to non-accrual loans	343.00%		343.00%		1071.00%
Residential loans \| Home equity \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	97		97		102
Residential loans \| Other residential
Allowance for loan losses:
Beginning balance	509	426	454	394
(Reversal of) provision for loan losses	33	22	88	54
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	542	448	542	448
Ending ALLL related to loans collectively evaluated for impairment	540		540		399
Ending ALLL related to loans individually evaluated for impairment	2		2		55
Ending ALLL	542		542		454
Collectively evaluated for impairment	95,778		95,778		76,584
Individually evaluated for impairment	1,159		1,159		1,965
Total loans	$ 96,937		$ 96,937		$ 78,549
Ratio of allowance for loan losses to total loans	0.56%		0.56%		0.58%
Residential loans \| Other residential \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	0		0		0
Consumer loans \| Installment and other consumer
Allowance for loan losses:
Beginning balance	340	437	372	425
(Reversal of) provision for loan losses	(5)	(73)	(40)	(84)
Charge-offs	(1)	0	(3)	(4)
Recoveries	1	0	6	27
Ending balance	335	364	335	364
Ending ALLL related to loans collectively evaluated for impairment	250		250		274
Ending ALLL related to loans individually evaluated for impairment	85		85		98
Ending ALLL	335		335		372
Collectively evaluated for impairment	24,310		24,310		24,563
Individually evaluated for impairment	666		666		932
Total loans	$ 24,976		$ 24,976		$ 25,495
Ratio of allowance for loan losses to total loans	1.34%		1.34%		1.46%
Allowance for loan losses to non-accrual loans					683.00%
Consumer loans \| Installment and other consumer \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	0		0		0
Unallocated
Allowance for loan losses:
Beginning balance	912	1,454	1,541	1,096
(Reversal of) provision for loan losses	(855)	119	(1,484)	477
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	57	$ 1,573	57	$ 1,573
Ending ALLL related to loans collectively evaluated for impairment	57		57		1,541
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	57		57		1,541
Collectively evaluated for impairment	0		0		0
Individually evaluated for impairment	0		0		0
Total loans	0		0		0
Unallocated \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	0		0		0
Purchased credit-impaired	$ 0		$ 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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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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A valuation allowance for financing receivables that are expected to be uncollectible.

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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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