Fair Value of Financial Instruments - Schedule of Level 3 Assets (Details) - Credit Risk and Non-Agency Securities - Significant Unobservable Inputs (Level 3) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 998,204	$ 1,052,170
Purchases of Credit Risk and Non-Agency Securities, at cost	0	8,224
Principal repayments of Credit Risk and Non-Agency Securities	0	(135,617)
Proceeds from sales of Credit Risk and Non-Agency Securities	0	(8,372)
Gain on Credit Risk and Non-Agency Securities	0	46,924
Accretion of net discount on Credit Risk and Non-Agency Securities	0	3,187
Level 3 transfered to Level 2	(998,204)	(966,516)
Balance, end of period	0	0
Gain on Credit Risk and Non-Agency Securities	$ 0	$ 46,924

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Net Change in Discount

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- Definition

Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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-Section S99
-Paragraph 2
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Section 50
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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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