Loans Receivable Held for Investment - Risk Category of Loans by Loan Type (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Credit Quality Indicators
Loans receivable	$ 358,485	$ 338,920
Single family
Credit Quality Indicators
Loans receivable	92,177	111,524
Multi-family
Credit Quality Indicators
Loans receivable	233,309	188,918
Commercial real estate
Credit Quality Indicators
Loans receivable	5,800	6,096
Church
Credit Quality Indicators
Loans receivable	25,096	30,512
Construction
Credit Quality Indicators
Loans receivable	1,872	1,671
Commercial - other
Credit Quality Indicators
Loans receivable	226	192
Consumer
Credit Quality Indicators
Loans receivable	5	7
Pass
Credit Quality Indicators
Loans receivable	352,291	331,712
Pass | Single family
Credit Quality Indicators
Loans receivable	92,132	111,513
Pass | Multi-family
Credit Quality Indicators
Loans receivable	232,642	187,946
Pass | Commercial real estate
Credit Quality Indicators
Loans receivable	5,800	5,974
Pass | Church
Credit Quality Indicators
Loans receivable	19,678	24,474
Pass | Construction
Credit Quality Indicators
Loans receivable	1,872	1,671
Pass | Commercial - other
Credit Quality Indicators
Loans receivable	162	127
Pass | Consumer
Credit Quality Indicators
Loans receivable	5	7
Watch
Credit Quality Indicators
Loans receivable	672	813
Watch | Commercial real estate
Credit Quality Indicators
Loans receivable		122
Watch | Church
Credit Quality Indicators
Loans receivable	672	691
Special Mention
Credit Quality Indicators
Loans receivable	35
Special Mention | Single family
Credit Quality Indicators
Loans receivable	35
Substandard
Credit Quality Indicators
Loans receivable	5,487	6,395
Substandard | Single family
Credit Quality Indicators
Loans receivable	10	11
Substandard | Multi-family
Credit Quality Indicators
Loans receivable	667	972
Substandard | Church
Credit Quality Indicators
Loans receivable	4,746	5,347
Substandard | Commercial - other
Credit Quality Indicators
Loans receivable	$ 64	$ 65