Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 18,884	$ 15,817	$ 16,677	$ 15,821
Provision (reversal)	2,000	0	4,200	0
Charge-offs	(20)	0	(20)	(9)
Recoveries	4	18	11	23
Ending balance	20,868	15,835	20,868	15,835
Ending ALLL related to loans collectively evaluated for impairment	20,434		20,434		$ 16,280
Ending ALLL related to loans individually evaluated for impairment	434		434		397
Ending ALLL	20,868		20,868		16,677
Collectively evaluated for impairment	2,098,301		2,098,301		1,831,786
Individually evaluated for impairment	11,900		11,900		11,500
Total loans	$ 2,110,201		$ 2,110,201		$ 1,843,286
Ratio of allowance for loan losses to total loans	0.99%		0.99%		0.90%
Allowance for loan losses to non-accrual loans	1315.00%		1315.00%		7379.00%
Commercial loans \| Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 2,784	2,612	$ 2,334	2,436
Provision (reversal)	(159)	(250)	287	(70)
Charge-offs	(20)	0	(20)	(9)
Recoveries	4	6	8	11
Ending balance	2,609	2,368	2,609	2,368
Ending ALLL related to loans collectively evaluated for impairment	2,599		2,599		$ 2,231
Ending ALLL related to loans individually evaluated for impairment	10		10		103
Ending ALLL	2,609		2,609		2,334
Collectively evaluated for impairment	524,539		524,539		245,464
Individually evaluated for impairment	578		578		1,223
Total loans	$ 525,117		$ 525,117		$ 246,687
Ratio of allowance for loan losses to total loans	0.50%		0.50%		0.95%
Commercial real estate loans \| Commercial real estate, owner-occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 2,797	2,358	$ 2,462	2,407
Provision (reversal)	113	(37)	448	(86)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	2,910	2,321	2,910	2,321
Ending ALLL related to loans collectively evaluated for impairment	2,718		2,718		$ 2,267
Ending ALLL related to loans individually evaluated for impairment	192		192		195
Ending ALLL	2,910		2,910		2,462
Collectively evaluated for impairment	289,161		289,161		301,826
Individually evaluated for impairment	7,002		7,002		6,998
Total loans	$ 296,163		$ 296,163		$ 308,824
Ratio of allowance for loan losses to total loans	0.98%		0.98%		0.80%
Commercial real estate loans \| Commercial real estate, investor-owned
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 9,225	7,766	$ 8,483	7,703
Provision (reversal)	1,178	(57)	1,920	6
Charge-offs	0	0	0	0
Recoveries	0	12	0	12
Ending balance	10,403	7,721	10,403	7,721
Ending ALLL related to loans collectively evaluated for impairment	10,339		10,339		$ 8,442
Ending ALLL related to loans individually evaluated for impairment	64		64		41
Ending ALLL	10,403		10,403		8,483
Collectively evaluated for impairment	943,725		943,725		944,547
Individually evaluated for impairment	2,664		2,664		1,770
Total loans	$ 946,389		$ 946,389		$ 946,317
Ratio of allowance for loan losses to total loans	1.10%		1.10%		0.90%
Allowance for loan losses to non-accrual loans	1147.00%		1147.00%
Commercial real estate loans \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 727	704	$ 638	756
Provision (reversal)	109	(85)	195	(137)
Charge-offs	0	0	0	0
Recoveries	0	0	3	0
Ending balance	836	619	836	619
Ending ALLL related to loans collectively evaluated for impairment	836		836		$ 638
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	836		836		638
Collectively evaluated for impairment	66,368		66,368		61,095
Individually evaluated for impairment	0		0		0
Total loans	$ 66,368		$ 66,368		$ 61,095
Ratio of allowance for loan losses to total loans	1.26%		1.26%		1.04%
Residential loans \| Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 982	923	$ 850	915
Provision (reversal)	62	(16)	194	(8)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	1,044	907	1,044	907
Ending ALLL related to loans collectively evaluated for impairment	1,040		1,040		$ 845
Ending ALLL related to loans individually evaluated for impairment	4		4		5
Ending ALLL	1,044		1,044		850
Collectively evaluated for impairment	112,035		112,035		115,606
Individually evaluated for impairment	876		876		418
Total loans	$ 112,911		$ 112,911		$ 116,024
Ratio of allowance for loan losses to total loans	0.92%		0.92%		0.73%
Allowance for loan losses to non-accrual loans	167.00%		167.00%		506.00%
Residential loans \| Other residential
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 1,098	800	$ 973	800
Provision (reversal)	168	49	293	49
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	1,266	849	1,266	849
Ending ALLL related to loans collectively evaluated for impairment	1,266		1,266		$ 973
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	1,266		1,266		973
Collectively evaluated for impairment	136,859		136,859		136,205
Individually evaluated for impairment	0		0		452
Total loans	$ 136,859		$ 136,859		$ 136,657
Ratio of allowance for loan losses to total loans	0.93%		0.93%		0.71%
Consumer loans \| Installment and other consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 363	340	$ 284	310
Provision (reversal)	63	(17)	142	13
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	426	323	426	323
Ending ALLL related to loans collectively evaluated for impairment	262		262		$ 231
Ending ALLL related to loans individually evaluated for impairment	164		164		53
Ending ALLL	426		426		284
Collectively evaluated for impairment	25,614		25,614		27,043
Individually evaluated for impairment	780		780		639
Total loans	$ 26,394		$ 26,394		$ 27,682
Ratio of allowance for loan losses to total loans	1.61%		1.61%		1.03%
Allowance for loan losses to non-accrual loans	775.00%		775.00%		490.00%
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 908	314	$ 653	494
Provision (reversal)	466	413	721	233
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	1,374	$ 727	1,374	$ 727
Ending ALLL related to loans collectively evaluated for impairment	1,374		1,374		$ 653
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	1,374		1,374		653
Collectively evaluated for impairment	0		0		0
Individually evaluated for impairment	0		0		0
Total loans	$ 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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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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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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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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