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Loans - Allowance for loan losses by segment (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Allowance for Loan Losses:
Beginning Balance	$ 22,526	$ 20,031	$ 20,031
Provision for Loan Losses	2,100	600
Loans Charged-off	(47)	(36)
Recoveries of Loans	6	12
Total Ending Allowance Balance	24,585	20,607	22,526
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Impairment				$ 49	$ 45
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				24,536	22,481
Loans and Leases Receivable, Allowance, Total	24,585	20,607	22,526	24,585	22,526
Loans, Individually Evaluated for Impairment				3,765	1,758
Loans, Collectively Evaluated for Impairment				1,999,052	1,910,280
Totals				2,002,817	1,912,038
Commercial
Allowance for Loan Losses:
Beginning Balance	3,058	2,898	2,898
Provision for Loan Losses	531	480
Loans Charged-off	(34)	(19)
Recoveries of Loans	2	2
Total Ending Allowance Balance	3,557	3,361	3,058
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Impairment				35	31
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				3,522	3,027
Loans and Leases Receivable, Allowance, Total	3,557	3,361	3,058	3,557	3,058
Loans, Individually Evaluated for Impairment				267	273
Loans, Collectively Evaluated for Impairment				299,158	275,762
Totals				299,425	276,035
Construction and Land Development
Allowance for Loan Losses:
Beginning Balance	2,202	2,451	2,451
Provision for Loan Losses	(71)	(354)
Total Ending Allowance Balance	2,131	2,097	2,202
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				2,131	2,202
Loans and Leases Receivable, Allowance, Total	2,131	2,097	2,202	2,131	2,202
Loans, Individually Evaluated for Impairment				170	176
Loans, Collectively Evaluated for Impairment				183,180	196,600
Totals				183,350	196,776
1-4 Family Mortgage
Allowance for Loan Losses:
Beginning Balance	2,839	2,597	2,597
Provision for Loan Losses	361	5
Recoveries of Loans	2	9
Total Ending Allowance Balance	3,202	2,611	2,839
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				3,202	2,839
Loans and Leases Receivable, Allowance, Total	3,202	2,611	2,839	3,202	2,839
Loans, Individually Evaluated for Impairment				1,243	1,059
Loans, Collectively Evaluated for Impairment				271,347	259,552
Totals				272,590	260,611
Multifamily
Allowance for Loan Losses:
Beginning Balance	5,824	4,644	4,644
Provision for Loan Losses	732	71
Total Ending Allowance Balance	6,556	4,715	5,824
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				6,556	5,824
Loans and Leases Receivable, Allowance, Total	6,556	4,715	5,824	6,556	5,824
Loans, Collectively Evaluated for Impairment				536,380	515,014
Totals				536,380	515,014
CRE Owner Occupied
Allowance for Loan Losses:
Beginning Balance	792	808	808
Provision for Loan Losses	146	(18)
Total Ending Allowance Balance	938	790	792
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				938	792
Loans and Leases Receivable, Allowance, Total	938	790	792	938	792
Loans, Individually Evaluated for Impairment				1,847	236
Loans, Collectively Evaluated for Impairment				73,360	66,348
Totals				75,207	66,584
CRE Non-owner Occupied
Allowance for Loan Losses:
Beginning Balance	6,972	5,872	5,872
Provision for Loan Losses	1,031	477
Total Ending Allowance Balance	8,003	6,349	6,972
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				8,003	6,972
Loans and Leases Receivable, Allowance, Total	8,003	6,349	6,972	8,003	6,972
Loans, Individually Evaluated for Impairment				224
Loans, Collectively Evaluated for Impairment				631,317	592,545
Totals				631,541	592,545
Consumer and other
Allowance for Loan Losses:
Beginning Balance	85	65	65
Provision for Loan Losses	18	12
Loans Charged-off	(13)	(17)
Recoveries of Loans	2	1
Total Ending Allowance Balance	92	61	85
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Impairment				14	14
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				78	71
Loans and Leases Receivable, Allowance, Total	92	61	85	92	85
Loans, Individually Evaluated for Impairment				14	14
Loans, Collectively Evaluated for Impairment				4,310	4,459
Totals				4,324	4,473
Unallocated
Allowance for Loan Losses:
Beginning Balance	754	696	696
Provision for Loan Losses	(648)	(73)
Total Ending Allowance Balance	106	623	754
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Impairment				106	754
Loans and Leases Receivable, Allowance, Total	$ 106	$ 623	$ 754	$ 106	$ 754