Loans and Allowance - Non-accrual loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	$ 4,512	$ 4,127
Transfer into non-accrual	643	177
Loans paid down/payoffs	(598)	(74)
Loans return to accrual status	(33)	(17)
Loans charged off	(82)	(125)
Balance	4,442	4,088
Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	4,299
Balance	4,303
Consumer Loan [Member]
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	213
Single-family residential | Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	270	790
Loans paid down/payoffs	(133)	(11)
Balance	137	779
Multifamily | Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance		24
Loans paid down/payoffs		(4)
Balance		20
Commercial | Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	4,029	3,139
Transfer into non-accrual	574
Loans paid down/payoffs	(437)	(32)
Balance	4,166	3,107
Commercial | Consumer Loan [Member]
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	139
Consumer | Consumer Loan [Member]
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	34	51
Loans paid down/payoffs	(1)	(5)
Loans return to accrual status	(33)
Balance		46
Automobile | Consumer Loan [Member]
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	179	123
Transfer into non-accrual	69	177
Loans paid down/payoffs	(27)	(22)
Loans return to accrual status		(17)
Loans charged off	(82)	(125)
Balance	$ 139	$ 136