Loans Receivable Held for Investment - Risk Category of Loans by Loan Type (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Credit Quality Indicators
Loans receivable	$ 338,920	$ 384,057
Single family
Credit Quality Indicators
Loans receivable	111,524	105,332
Multi-family
Credit Quality Indicators
Loans receivable	188,918	231,440
Commercial real estate
Credit Quality Indicators
Loans receivable	6,096	8,921
Church
Credit Quality Indicators
Loans receivable	30,512	37,223
Construction
Credit Quality Indicators
Loans receivable	1,671	827
Commercial - other
Credit Quality Indicators
Loans receivable	192	308
Consumer
Credit Quality Indicators
Loans receivable	7	6
Pass
Credit Quality Indicators
Loans receivable	331,712	369,454
Pass | Single family
Credit Quality Indicators
Loans receivable	111,513	105,332
Pass | Multi-family
Credit Quality Indicators
Loans receivable	187,946	228,522
Pass | Commercial real estate
Credit Quality Indicators
Loans receivable	5,974	6,965
Pass | Church
Credit Quality Indicators
Loans receivable	24,474	27,560
Pass | Construction
Credit Quality Indicators
Loans receivable	1,671	827
Pass | Commercial - other
Credit Quality Indicators
Loans receivable	127	242
Pass | Consumer
Credit Quality Indicators
Loans receivable	7	6
Watch
Credit Quality Indicators
Loans receivable	813	2,417
Watch | Multi-family
Credit Quality Indicators
Loans receivable		1,274
Watch | Commercial real estate
Credit Quality Indicators
Loans receivable	122
Watch | Church
Credit Quality Indicators
Loans receivable	691	1,143
Special Mention
Credit Quality Indicators
Loans receivable		1,165
Special Mention | Multi-family
Credit Quality Indicators
Loans receivable		342
Special Mention | Church
Credit Quality Indicators
Loans receivable		823
Substandard
Credit Quality Indicators
Loans receivable	6,395	11,021
Substandard | Single family
Credit Quality Indicators
Loans receivable	11
Substandard | Multi-family
Credit Quality Indicators
Loans receivable	972	1,302
Substandard | Commercial real estate
Credit Quality Indicators
Loans receivable		1,956
Substandard | Church
Credit Quality Indicators
Loans receivable	5,347	7,697
Substandard | Commercial - other
Credit Quality Indicators
Loans receivable	$ 65	$ 66