Loans Receivable Held for Investment - Aging of Recorded Investment in Past Due Loans by Loan Type (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Past due receivable
Total Past Due	$ 70	$ 35
Current	356,043	358,450
Gross loans receivable after deferred loan costs and premiums	356,113	358,485
30-59 Days Past Due
Past due receivable
Total Past Due	36	35
Greater than 90 Days Past Due
Past due receivable
Total Past Due	34
Single family
Past due receivable
Total Past Due	70	35
Current	85,321	92,142
Gross loans receivable after deferred loan costs and premiums	85,391	92,177
Single family | 30-59 Days Past Due
Past due receivable
Total Past Due	36	35
Single family | Greater than 90 Days Past Due
Past due receivable
Total Past Due	34
Multi-family
Past due receivable
Current	239,900	233,309
Gross loans receivable after deferred loan costs and premiums	239,900	233,309
Commercial real estate
Past due receivable
Current	6,436	5,800
Gross loans receivable after deferred loan costs and premiums	6,436	5,800
Church
Past due receivable
Current	21,868	25,096
Gross loans receivable after deferred loan costs and premiums	21,868	25,096
Construction
Past due receivable
Current	2,242	1,872
Gross loans receivable after deferred loan costs and premiums	2,242	1,872
Commercial - other
Past due receivable
Current	264	226
Gross loans receivable after deferred loan costs and premiums	264	226
Consumer
Past due receivable
Current	12	5
Gross loans receivable after deferred loan costs and premiums	$ 12	$ 5