Loans Receivable Held for Investment - Risk Category of Loans by Loan Type (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Credit Quality Indicators
Loans receivable	$ 401,029	$ 358,485
Single family
Credit Quality Indicators
Loans receivable	73,112	92,177
Multi-family
Credit Quality Indicators
Loans receivable	289,043	233,309
Commercial real estate
Credit Quality Indicators
Loans receivable	14,818	5,800
Church
Credit Quality Indicators
Loans receivable	20,648	25,096
Construction
Credit Quality Indicators
Loans receivable	3,125	1,872
Commercial - other
Credit Quality Indicators
Loans receivable	262	226
Consumer
Credit Quality Indicators
Loans receivable	21	5
Pass
Credit Quality Indicators
Loans receivable	396,054	352,291
Pass | Single family
Credit Quality Indicators
Loans receivable	73,094	92,132
Pass | Multi-family
Credit Quality Indicators
Loans receivable	288,251	232,642
Pass | Commercial real estate
Credit Quality Indicators
Loans receivable	14,818	5,800
Pass | Church
Credit Quality Indicators
Loans receivable	16,546	19,678
Pass | Construction
Credit Quality Indicators
Loans receivable	3,125	1,872
Pass | Commercial - other
Credit Quality Indicators
Loans receivable	199	162
Pass | Consumer
Credit Quality Indicators
Loans receivable	21	5
Watch
Credit Quality Indicators
Loans receivable	822	672
Watch | Multi-family
Credit Quality Indicators
Loans receivable	411
Watch | Church
Credit Quality Indicators
Loans receivable	411	672
Special Mention
Credit Quality Indicators
Loans receivable		35
Special Mention | Single family
Credit Quality Indicators
Loans receivable		35
Substandard
Credit Quality Indicators
Loans receivable	4,153	5,487
Substandard | Single family
Credit Quality Indicators
Loans receivable	18	10
Substandard | Multi-family
Credit Quality Indicators
Loans receivable	381	667
Substandard | Church
Credit Quality Indicators
Loans receivable	3,691	4,746
Substandard | Commercial - other
Credit Quality Indicators
Loans receivable	$ 63	$ 64