Loans Receivable Held for Investment - Risk Category of Loans by Loan Type (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Credit Quality Indicators
Loans receivable	$ 384,545	$ 401,029
Single family
Credit Quality Indicators
Loans receivable	64,286	73,112
Multi-family
Credit Quality Indicators
Loans receivable	285,239	289,043
Commercial real estate
Credit Quality Indicators
Loans receivable	14,742	14,818
Church
Credit Quality Indicators
Loans receivable	19,269	20,648
Construction
Credit Quality Indicators
Loans receivable	717	3,125
Commercial - other
Credit Quality Indicators
Loans receivable	268	262
Consumer
Credit Quality Indicators
Loans receivable	24	21
Pass
Credit Quality Indicators
Loans receivable	379,747	396,054
Pass | Single family
Credit Quality Indicators
Loans receivable	64,272	73,094
Pass | Multi-family
Credit Quality Indicators
Loans receivable	284,456	288,251
Pass | Commercial real estate
Credit Quality Indicators
Loans receivable	14,742	14,818
Pass | Church
Credit Quality Indicators
Loans receivable	15,330	16,546
Pass | Construction
Credit Quality Indicators
Loans receivable	717	3,125
Pass | Commercial - other
Credit Quality Indicators
Loans receivable	206	199
Pass | Consumer
Credit Quality Indicators
Loans receivable	24	21
Watch
Credit Quality Indicators
Loans receivable	1,486	822
Watch | Multi-family
Credit Quality Indicators
Loans receivable	406	411
Watch | Church
Credit Quality Indicators
Loans receivable	1,080	411
Substandard
Credit Quality Indicators
Loans receivable	3,312	4,153
Substandard | Single family
Credit Quality Indicators
Loans receivable	14	18
Substandard | Multi-family
Credit Quality Indicators
Loans receivable	377	381
Substandard | Church
Credit Quality Indicators
Loans receivable	2,859	3,691
Substandard | Commercial - other
Credit Quality Indicators
Loans receivable	$ 62	$ 63