Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Allowance for loan losses:
Beginning balance	$ 15,817	$ 15,771	$ 15,821	$ 15,767
Provision for loan losses	0	0	0	0
Charge-offs	0	(5)	(9)	(5)
Recoveries	18	47	23	51
Ending balance	15,835	15,813	15,835	15,813
Ending ALLL related to loans collectively evaluated for impairment	15,259		15,259		$ 15,043
Ending ALLL related to loans individually evaluated for impairment	576		576		778
Ending ALLL	15,835		15,835		15,821
Collectively evaluated for impairment	1,750,495		1,750,495		1,746,714
Individually evaluated for impairment	12,303		12,303		15,038
Total loans	$ 1,764,879		$ 1,764,879		$ 1,763,864
Ratio of allowance for loan losses to total loans	0.90%		0.90%		0.90%
Allowance for loan losses to non-accrual loans	2759.00%		2759.00%		2270.00%
Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	2,081		2,081		2,112
Commercial loans \| Commercial and industrial
Allowance for loan losses:
Beginning balance	2,612	3,693	2,436	3,654
Provision for loan losses	(250)	(1,098)	(70)	(1,063)
Charge-offs	0	(3)	(9)	(3)
Recoveries	6	5	11	9
Ending balance	2,368	2,597	2,368	2,597
Ending ALLL related to loans collectively evaluated for impairment	2,026		2,026		1,970
Ending ALLL related to loans individually evaluated for impairment	342		342		466
Ending ALLL	2,368		2,368		2,436
Collectively evaluated for impairment	233,326		233,326		228,883
Individually evaluated for impairment	1,489		1,489		1,825
Total loans	$ 234,832		$ 234,832		$ 230,739
Ratio of allowance for loan losses to total loans	1.01%		1.01%		1.06%
Allowance for loan losses to non-accrual loans	669.00%		669.00%
Commercial loans \| Commercial and industrial \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	17		17		31
Commercial real estate loans \| Commercial real estate, owner-occupied
Allowance for loan losses:
Beginning balance	2,358	2,080	2,407	2,294
Provision for loan losses	(37)	259	(86)	45
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	2,321	2,339	2,321	2,339
Ending ALLL related to loans collectively evaluated for impairment	2,198		2,198		2,218
Ending ALLL related to loans individually evaluated for impairment	123		123		189
Ending ALLL	2,321		2,321		2,407
Collectively evaluated for impairment	298,162		298,162		305,097
Individually evaluated for impairment	7,000		7,000		6,993
Total loans	$ 306,327		$ 306,327		$ 313,277
Ratio of allowance for loan losses to total loans	0.76%		0.76%		0.77%
Commercial real estate loans \| Commercial real estate, owner-occupied \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	1,165		1,165		1,187
Commercial real estate loans \| Commercial real estate, investor
Allowance for loan losses:
Beginning balance	7,766	6,455	7,703	6,475
Provision for loan losses	(57)	935	6	915
Charge-offs	0	0	0	0
Recoveries	12	0	12	0
Ending balance	7,721	7,390	7,721	7,390
Ending ALLL related to loans collectively evaluated for impairment	7,679		7,679		7,658
Ending ALLL related to loans individually evaluated for impairment	42		42		45
Ending ALLL	7,721		7,721		7,703
Collectively evaluated for impairment	876,351		876,351		870,778
Individually evaluated for impairment	1,796		1,796		1,821
Total loans	$ 878,969		$ 878,969		$ 873,410
Ratio of allowance for loan losses to total loans	0.88%		0.88%		0.88%
Commercial real estate loans \| Commercial real estate, investor \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	822		822		811
Commercial real estate loans \| Construction
Allowance for loan losses:
Beginning balance	704	697	756	681
Provision for loan losses	(85)	(189)	(137)	(173)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	619	508	619	508
Ending ALLL related to loans collectively evaluated for impairment	619		619		756
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	619		619		756
Collectively evaluated for impairment	63,075		63,075		73,735
Individually evaluated for impairment	488		488		2,688
Total loans	$ 63,563		$ 63,563		$ 76,423
Ratio of allowance for loan losses to total loans	0.97%		0.97%		0.99%
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	923	979	915	1,031
Provision for loan losses	(16)	(27)	(8)	(79)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	907	952	907	952
Ending ALLL related to loans collectively evaluated for impairment	902		902		910
Ending ALLL related to loans individually evaluated for impairment	5		5		5
Ending ALLL	907		907		915
Collectively evaluated for impairment	125,483		125,483		124,049
Individually evaluated for impairment	408		408		564
Total loans	$ 125,968		$ 125,968		$ 124,696
Ratio of allowance for loan losses to total loans	0.72%		0.72%		0.73%
Allowance for loan losses to non-accrual loans	578.00%		578.00%		292.00%
Residential loans \| Home equity \| Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	77		77		83
Residential loans \| Other residential
Allowance for loan losses:
Beginning balance	800	543	800	536
Provision for loan losses	49	203	49	210
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	849	746	849	746
Ending ALLL related to loans collectively evaluated for impairment	849		849		800
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	849		849		800
Collectively evaluated for impairment	123,663		123,663		117,385
Individually evaluated for impairment	457		457		462
Total loans	$ 124,120		$ 124,120		$ 117,847
Ratio of allowance for loan losses to total loans	0.68%		0.68%		0.68%
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	351	310	378
Provision for loan losses	(17)	(66)	13	(93)
Charge-offs	0	(2)	0	(2)
Recoveries	0	42	0	42
Ending balance	323	325	323	325
Ending ALLL related to loans collectively evaluated for impairment	259		259		237
Ending ALLL related to loans individually evaluated for impairment	64		64		73
Ending ALLL	323		323		310
Collectively evaluated for impairment	30,435		30,435		26,787
Individually evaluated for impairment	665		665		685
Total loans	$ 31,100		$ 31,100		$ 27,472
Ratio of allowance for loan losses to total loans	1.04%		1.04%		1.13%
Allowance for loan losses to non-accrual loans	513.00%		513.00%
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	314	973	494	718
Provision for loan losses	413	(17)	233	238
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	727	$ 956	727	$ 956
Ending ALLL related to loans collectively evaluated for impairment	727		727		494
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	727		727		494
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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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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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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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, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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

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