Loans - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	$ 694,234	$ 621,907
Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	575,849	593,823
Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	91,645	3,353
Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	12,732	9,988
Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	14,008	14,743
Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Commercial business
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	109,719	38,931
Commercial business | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	105,242	35,347
Commercial business | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	1,159	378
Commercial business | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	519	1,649
Commercial business | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	2,799	1,557
Commercial business | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Commercial business | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
One-to-four family
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	137,988	149,393
One-to-four family | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	118,686	138,900
One-to-four family | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	14,470	0
One-to-four family | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	2,484
One-to-four family | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	4,832	8,009
One-to-four family | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
One-to-four family | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Home equity
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	19,286	23,845
Home equity | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	17,920	23,206
Home equity | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	735	0
Home equity | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Home equity | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	631	639
Home equity | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Home equity | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Commercial and multifamily
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	273,084	261,268
Commercial and multifamily | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	231,980	256,139
Commercial and multifamily | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	31,262	217
Commercial and multifamily | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	4,950	2,178
Commercial and multifamily | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	4,892	2,734
Commercial and multifamily | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Commercial and multifamily | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Construction and land
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	76,089	75,756
Construction and land | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	25,788	68,268
Construction and land | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	42,989	2,634
Construction and land | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	7,263	3,677
Construction and land | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	49	1,177
Construction and land | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Construction and land | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Manufactured homes
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	21,227	20,613
Manufactured homes | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	19,966	20,204
Manufactured homes | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	1,030	124
Manufactured homes | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Manufactured homes | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	231	285
Manufactured homes | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Manufactured homes | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Floating homes
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	46,256	43,799
Floating homes | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	45,725	43,509
Floating homes | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Floating homes | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Floating homes | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	531	290
Floating homes | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Floating homes | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Other consumer
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	10,585	8,302
Other consumer | Pass
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	10,542	8,250
Other consumer | Watch
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Other consumer | Special Mention
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Other consumer | Substandard
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	43	52
Other consumer | Doubtful
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	0	0
Other consumer | Loss
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total loans held-for-portfolio	$ 0	$ 0