Real Estate Securities - Components of Carrying Value (Which Equals Fair Value) of Residential Available for Sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	$ 610,270	$ 829,245
Senior Securities
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	73,324	279,251
Senior Securities \| Prime
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	65,195	210,993
Senior Securities \| Non-prime
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	8,129	68,258
Re-REMIC
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	165,707	165,064
Subordinate Securities
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	371,239	384,930
Residential
Schedule of Available-for-sale Securities [Line Items]
Principal balance	743,745	973,227
Credit reserve	(44,943)	(48,869)
Unamortized discount, net	(207,574)	(237,107)
Amortized cost	491,228	687,251
Gross unrealized gains	123,310	147,001
Gross unrealized losses	(4,268)	(5,007)
Carrying Value	610,270	829,245
Residential \| Senior Securities \| Prime
Schedule of Available-for-sale Securities [Line Items]
Principal balance	70,717	217,605
Credit reserve	(987)	(1,305)
Unamortized discount, net	(6,614)	(22,079)
Amortized cost	63,116	194,221
Gross unrealized gains	4,503	20,263
Gross unrealized losses	(2,423)	(3,491)
Carrying Value	65,196	210,993
Residential \| Senior Securities \| Non-prime
Schedule of Available-for-sale Securities [Line Items]
Principal balance	10,137	75,591
Credit reserve	(622)	(5,101)
Unamortized discount, net	(1,813)	(8,395)
Amortized cost	7,702	62,095
Gross unrealized gains	426	6,249
Gross unrealized losses	0	(86)
Carrying Value	8,128	68,258
Residential \| Re-REMIC
Schedule of Available-for-sale Securities [Line Items]
Principal balance	188,404	189,782
Credit reserve	(9,352)	(10,332)
Unamortized discount, net	(64,484)	(71,670)
Amortized cost	114,568	107,780
Gross unrealized gains	51,139	57,284
Gross unrealized losses	0	0
Carrying Value	165,707	165,064
Residential \| Subordinate Securities
Schedule of Available-for-sale Securities [Line Items]
Principal balance	474,487	490,249
Credit reserve	(33,982)	(32,131)
Unamortized discount, net	(134,663)	(134,963)
Amortized cost	305,842	323,155
Gross unrealized gains	67,242	63,205
Gross unrealized losses	(1,845)	(1,430)
Carrying Value	$ 371,239	$ 384,930

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.

+ 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 (c)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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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
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-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ 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 210.5-02.2)
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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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