Loans - Summary of balance in allowance for loan losses and recorded investment in loans by class and based on impairment method (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Ending allowance balance attributable to loans:
Individually evaluated for impairment	$ 0	$ 0
Collectively evaluated for impairment	5,629	4,264
Total ending allowance balance	5,629	4,264	$ 3,413	$ 2,799
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	467,149	348,089
Total ending loans balance	467,149	348,089
Real Estate \| 1 - 4 Family Residential
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	407	382
Total ending allowance balance	407	382	360	213
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	56,043	51,556
Total ending loans balance	56,043	51,556
Real Estate \| Multifamily
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	952	713
Total ending allowance balance	952	713	621	533
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	136,537	98,432
Total ending loans balance	136,537	98,432
Real Estate \| Commercial Real Estate
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	357	266
Total ending allowance balance	357	266	238	230
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	33,145	24,761
Total ending loans balance	33,145	24,761
Real Estate \| Construction
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	149	127
Total ending allowance balance	149	127	141	134
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	5,921	5,047
Total ending loans balance	5,921	5,047
Commercial
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	3,110	2,272
Total ending allowance balance	3,110	2,272	1,934	1,536
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	191,828	136,412
Total ending loans balance	191,828	136,412
Consumer
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	654	504
Total ending allowance balance	654	504	$ 119	$ 153
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	43,675	31,881
Total ending loans balance	$ 43,675	$ 31,881

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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

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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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The balance of financing receivables 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 fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

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