Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 20,868	$ 15,835	$ 16,677	$ 15,821
Provision (reversal)	1,250	400	5,450	400
Charge-offs	(10)	0	(30)	(9)
Recoveries	5	5	16	28
Ending balance	22,113	16,240	22,113	16,240
Ending ALLL related to loans collectively evaluated for impairment	21,007		21,007		$ 16,280
Ending ALLL related to loans individually evaluated for impairment	1,106		1,106		397
Ending ALLL	22,113		22,113		16,677
Collectively evaluated for impairment	2,094,224		2,094,224		1,831,786
Individually evaluated for impairment	13,767		13,767		11,500
Total loans	$ 2,107,991		$ 2,107,991		$ 1,843,286
Ratio of allowance for loan losses to total loans	1.05%		1.05%		0.90%
Allowance for loan losses to non-accrual loans	1533.00%		1533.00%		7379.00%
Commercial loans \| Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 2,609	2,368	$ 2,334	2,436
Provision (reversal)	(79)	326	208	256
Charge-offs	(10)	0	(30)	(9)
Recoveries	5	5	13	16
Ending balance	2,525	2,699	2,525	2,699
Ending ALLL related to loans collectively evaluated for impairment	2,506		2,506		$ 2,231
Ending ALLL related to loans individually evaluated for impairment	19		19		103
Ending ALLL	2,525		2,525		2,334
Collectively evaluated for impairment	511,956		511,956		245,464
Individually evaluated for impairment	1,017		1,017		1,223
Total loans	$ 512,973		$ 512,973		$ 246,687
Ratio of allowance for loan losses to total loans	0.49%		0.49%		0.95%
Commercial real estate loans \| Commercial real estate, owner-occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 2,910	2,321	$ 2,462	2,407
Provision (reversal)	225	21	673	(65)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	3,135	2,342	3,135	2,342
Ending ALLL related to loans collectively evaluated for impairment	2,910		2,910		$ 2,267
Ending ALLL related to loans individually evaluated for impairment	225		225		195
Ending ALLL	3,135		3,135		2,462
Collectively evaluated for impairment	292,751		292,751		301,826
Individually evaluated for impairment	7,003		7,003		6,998
Total loans	$ 299,754		$ 299,754		$ 308,824
Ratio of allowance for loan losses to total loans	1.05%		1.05%		0.80%
Commercial real estate loans \| Commercial real estate, investor-owned
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 10,403	7,721	$ 8,483	7,703
Provision (reversal)	1,221	211	3,141	217
Charge-offs	0	0	0	0
Recoveries	0	0	0	12
Ending balance	11,624	7,932	11,624	7,932
Ending ALLL related to loans collectively evaluated for impairment	10,927		10,927		$ 8,442
Ending ALLL related to loans individually evaluated for impairment	697		697		41
Ending ALLL	11,624		11,624		8,483
Collectively evaluated for impairment	962,322		962,322		944,547
Individually evaluated for impairment	4,195		4,195		1,770
Total loans	$ 966,517		$ 966,517		$ 946,317
Ratio of allowance for loan losses to total loans	1.20%		1.20%		0.90%
Allowance for loan losses to non-accrual loans	1312.00%		1312.00%
Commercial real estate loans \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 836	619	$ 638	756
Provision (reversal)	24	(117)	219	(254)
Charge-offs	0	0	0	0
Recoveries	0	0	3	0
Ending balance	860	502	860	502
Ending ALLL related to loans collectively evaluated for impairment	860		860		$ 638
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	860		860		638
Collectively evaluated for impairment	66,663		66,663		61,095
Individually evaluated for impairment	0		0		0
Total loans	$ 66,663		$ 66,663		$ 61,095
Ratio of allowance for loan losses to total loans	1.29%		1.29%		1.04%
Residential loans \| Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 1,044	907	$ 850	915
Provision (reversal)	(6)	(28)	188	(36)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	1,038	879	1,038	879
Ending ALLL related to loans collectively evaluated for impairment	1,034		1,034		$ 845
Ending ALLL related to loans individually evaluated for impairment	4		4		5
Ending ALLL	1,038		1,038		850
Collectively evaluated for impairment	106,581		106,581		115,606
Individually evaluated for impairment	783		783		418
Total loans	$ 107,364		$ 107,364		$ 116,024
Ratio of allowance for loan losses to total loans	0.97%		0.97%		0.73%
Allowance for loan losses to non-accrual loans	195.00%		195.00%		506.00%
Residential loans \| Other residential
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 1,266	849	$ 973	800
Provision (reversal)	(6)	56	287	105
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	1,260	905	1,260	905
Ending ALLL related to loans collectively evaluated for impairment	1,260		1,260		$ 973
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	1,260		1,260		973
Collectively evaluated for impairment	130,915		130,915		136,205
Individually evaluated for impairment	0		0		452
Total loans	$ 130,915		$ 130,915		$ 136,657
Ratio of allowance for loan losses to total loans	0.96%		0.96%		0.71%
Consumer loans \| Installment and other consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 426	323	$ 284	310
Provision (reversal)	(20)	(28)	122	(15)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	406	295	406	295
Ending ALLL related to loans collectively evaluated for impairment	245		245		$ 231
Ending ALLL related to loans individually evaluated for impairment	161		161		53
Ending ALLL	406		406		284
Collectively evaluated for impairment	23,036		23,036		27,043
Individually evaluated for impairment	769		769		639
Total loans	$ 23,805		$ 23,805		$ 27,682
Ratio of allowance for loan losses to total loans	1.71%		1.71%		1.03%
Allowance for loan losses to non-accrual loans	1692.00%		1692.00%		490.00%
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 1,374	727	$ 653	494
Provision (reversal)	(109)	(41)	612	192
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	1,265	$ 686	1,265	$ 686
Ending ALLL related to loans collectively evaluated for impairment	1,265		1,265		$ 653
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	1,265		1,265		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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