Real Estate Securities - Components of Carrying Value (Which Equals Fair Value) of Residential Available for Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	$ 536,138	$ 572,752
Senior IO Securities
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	153,232	136,546
Re-REMIC
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	39,033	85,479
Subordinate Securities
Schedule of Available-for-sale Securities [Line Items]
Carrying Value	343,873	350,727
Residential
Schedule of Available-for-sale Securities [Line Items]
Principal balance	644,051	700,829
Credit reserve	(46,875)	(47,473)
Unamortized discount, net	(189,392)	(198,112)
Amortized cost	407,784	455,244
Gross unrealized gains	130,699	120,677
Gross unrealized losses	(2,345)	(3,169)
Carrying Value	536,138	572,752
Residential \| Senior IO Securities
Schedule of Available-for-sale Securities [Line Items]
Principal balance	156,936	148,862
Credit reserve	(3,024)	(4,814)
Unamortized discount, net	(36,575)	(41,877)
Amortized cost	117,337	102,171
Gross unrealized gains	37,155	36,304
Gross unrealized losses	(1,260)	(1,929)
Carrying Value	153,232	136,546
Residential \| Re-REMIC
Schedule of Available-for-sale Securities [Line Items]
Principal balance	44,896	95,608
Credit reserve	(5,810)	(6,857)
Unamortized discount, net	(10,412)	(19,613)
Amortized cost	28,674	69,138
Gross unrealized gains	10,359	16,341
Gross unrealized losses	0	0
Carrying Value	39,033	85,479
Residential \| Subordinate Securities
Schedule of Available-for-sale Securities [Line Items]
Principal balance	442,219	456,359
Credit reserve	(38,041)	(35,802)
Unamortized discount, net	(142,405)	(136,622)
Amortized cost	261,773	283,935
Gross unrealized gains	83,185	68,032
Gross unrealized losses	(1,085)	(1,240)
Carrying Value	$ 343,873	$ 350,727

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=73527792&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=73527792&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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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.

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-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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