Repurchase Agreements - Amounts Outstanding and Secured by Assets Pledged as Collateral (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	$ 87,571	$ 2,352,102
Fair Value of Collateral Pledged	156,523	2,839,379
Amortized Cost of Collateral Pledged	214,328	2,643,541
Agency RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	0	812,742
Fair Value of Collateral Pledged	0	865,765
Amortized Cost of Collateral Pledged	0	864,428
Agency RMBS \| VIE, Primary Beneficiary \| Consolidated SLST
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fair value amount		26,200
Agency CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	0	133,184
Fair Value of Collateral Pledged	0	139,317
Amortized Cost of Collateral Pledged	0	140,118
Agency CMBS \| VIE, Primary Beneficiary \| Consolidated K-Series
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fair value amount		88,400
Non-Agency RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	87,571	594,286
Fair Value of Collateral Pledged	156,523	797,784
Amortized Cost of Collateral Pledged	214,328	785,952
Non-Agency RMBS \| VIE, Primary Beneficiary \| Consolidated SLST
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fair value amount	156,500	214,800
CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	0	811,890
Fair Value of Collateral Pledged	0	1,036,513
Amortized Cost of Collateral Pledged	$ 0	853,043
CMBS \| VIE, Primary Beneficiary \| Consolidated K-Series
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fair value amount		$ 848,200

Amortized Cost Of Collateral Pledged.

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- Definition

The fair value as of the balance sheet date of financial instruments and other positions owned by the entity and pledged to counterparties as collateral, including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
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+ 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
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