Loans Receivable Held for Investment - Average of Loans Individually Evaluated for Impairment by Loan Type and Related Interest Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Impaired loans
Average Recorded Investment	$ 10,958	$ 13,669
Cash Basis Interest Income Recognized	875	1,173
Foregone interest income if impaired loans had performed according to terms	126	69
Single family
Impaired loans
Average Recorded Investment	636	824
Cash Basis Interest Income Recognized	28	253
Multi-family
Impaired loans
Average Recorded Investment	589	916
Cash Basis Interest Income Recognized	44	155
Commercial real estate
Impaired loans
Average Recorded Investment	305	983
Cash Basis Interest Income Recognized	104	271
Church
Impaired loans
Average Recorded Investment	9,363	10,880
Cash Basis Interest Income Recognized	693	489
Commercial - other
Impaired loans
Average Recorded Investment	65	66
Cash Basis Interest Income Recognized	$ 6	$ 5

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- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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- Definition

Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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- Definition

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18794-111554

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