Mortgage Loans Held for Investment, Net and Related Non-Recourse Collateralized Financing (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Single-family mortgage loans held for investment, amortized cost	$ 19,317	$ 24,337
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	1,094	1,343
Allowance for loan losses	(281)	(192)
Provision for Loan and Lease Losses	$ 130	180	$ 0
Debt Instrument, Description of Variable Rate Basis	1-month LIBOR
Debt Instrument, Basis Spread on Variable Rate	0.30%
Debt Instrument, Maturity Date	Jan. 31, 2025
Pledged Financial Instruments, Not Separately Reported, Loans Receivable, for Other Arrangements	$ 7,200	9,220
Non-Recourse Debt	$ 6,533	$ 8,573

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The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6873192&loc=d3e21338-158488

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
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This is the principal amount of loans (across all types of loans) that are overdue in payment by a set number of days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (e)(4)
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Amount before allowance of consumer real estate loans. Includes, but not limited to, construction financing, residential mortgage loans, and home equity lines of credit. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
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-Subparagraph (SX 210.9-03.7(a)(2),(3),(b))
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Amount of debt for which creditor does not have general recourse to the debtor but rather has recourse only to the property used for collateral in the transaction or other specific property.

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The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of other debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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