Repurchase Agreements - Assets Pledged as Collateral (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	$ 1,823,910	$ 1,543,577
Fair Value of Collateral Pledged	2,152,081	1,784,191
Amortized Cost of Collateral Pledged	1,962,280	1,672,486
Consolidated K-Series
Financial Instruments Owned and Pledged as Collateral [Line Items]
K-Series, carrying value	885,100	657,600
Agency ARMs
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	55,598	67,648
Fair Value of Collateral Pledged	57,546	70,747
Amortized Cost of Collateral Pledged	58,993	73,290
Agency Fixed- Rate
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	785,266	857,582
Fair Value of Collateral Pledged	830,400	907,610
Amortized Cost of Collateral Pledged	832,071	940,994
Non-Agency RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	210,339	88,730
Fair Value of Collateral Pledged	288,014	117,958
Amortized Cost of Collateral Pledged	280,724	118,414
CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	772,707	529,617
Fair Value of Collateral Pledged	976,121	687,876
Amortized Cost of Collateral Pledged	790,492	539,788
CMBS \| Consolidated K-Series
Financial Instruments Owned and Pledged as Collateral [Line Items]
K-Series, carrying value	$ 773,400	$ 543,000

Amortized Cost Of Collateral Pledged.

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- Definition

Represents the aggregate carrying value of the investment in the multi-family loans held in securitization trusts.

+ References

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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.

+ References

No definition available.

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- Definition

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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- Definition

Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

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