Real Estate Securities - Components of Carrying Value (Which Equals Fair Value) of Residential Available for Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	$ 829,245	$ 1,267,624
Senior Securities
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	279,251	487,557
Senior Securities \| Prime
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	210,993	307,813
Senior Securities \| Non-prime
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	68,258	179,744
Re-REMIC
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	165,064	168,347
Subordinate Securities
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	384,930	611,720
Subordinate Securities \| Prime
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	220,141	448,838
Subordinate Securities \| Non-prime
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	1,000	1,000
Residential
Schedule of Available-for-sale Securities [Line Items]
Principal balance	973,227	1,445,079
Credit reserve	(48,869)	(70,067)
Unamortized discount, net	(237,107)	(296,342)
Amortized cost	687,251	1,078,670
Amortized cost	687,251	1,078,670
Gross unrealized gains	147,001	191,750
Gross unrealized losses	(5,007)	(2,796)
Carrying Value	829,245	1,267,624
Residential \| Senior Securities \| Prime
Schedule of Available-for-sale Securities [Line Items]
Principal balance	217,605	311,573
Credit reserve	(1,305)	(3,660)
Unamortized discount, net	(22,079)	(34,782)
Amortized cost	194,221	273,131
Amortized cost	194,221	273,131
Gross unrealized gains	20,263	35,980
Gross unrealized losses	(3,491)	(1,298)
Carrying Value	210,993	307,813
Residential \| Senior Securities \| Non-prime
Schedule of Available-for-sale Securities [Line Items]
Principal balance	75,591	196,258
Credit reserve	(5,101)	(9,644)
Unamortized discount, net	(8,395)	(31,491)
Amortized cost	62,095	155,123
Amortized cost	62,095	155,123
Gross unrealized gains	6,249	24,682
Gross unrealized losses	(86)	(61)
Carrying Value	68,258	179,744
Residential \| Re-REMIC
Schedule of Available-for-sale Securities [Line Items]
Principal balance	189,782	195,098
Credit reserve	(10,332)	(15,202)
Unamortized discount, net	(71,670)	(79,611)
Amortized cost	107,780	100,285
Amortized cost	107,780	100,285
Gross unrealized gains	57,284	68,062
Gross unrealized losses	0	0
Carrying Value	165,064	168,347
Residential \| Subordinate Securities
Schedule of Available-for-sale Securities [Line Items]
Principal balance	490,249	742,150
Credit reserve	(32,131)	(41,561)
Unamortized discount, net	(134,963)	(150,458)
Amortized cost	323,155	550,131
Amortized cost	323,155	550,131
Gross unrealized gains	63,205	63,026
Gross unrealized losses	(1,430)	(1,437)
Carrying Value	$ 384,930	$ 611,720

Balance of credit reserve on available-for-sale securities.

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Available For Sale Securities Principal Balance

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Balance of net unamortized discount on available-for-sale securities.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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