Repurchase Agreements - Assets Pledged as Collateral (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Borrowings	$ 2,352,102
Fair Value of Collateral Pledged	2,839,379
Amortized Cost Of Collateral Pledged	2,643,541
Agency RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Borrowings	812,742
Fair Value of Collateral Pledged	865,765
Amortized Cost Of Collateral Pledged	864,428
Agency RMBS \| Consolidated SLST \| VIE, Primary Beneficiary
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities owned and pledged as collateral, fair value	26,200
Agency CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Borrowings	133,184
Fair Value of Collateral Pledged	139,317
Amortized Cost Of Collateral Pledged	140,118
Agency CMBS \| Consolidated K-Series \| VIE, Primary Beneficiary
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities owned and pledged as collateral, fair value	88,400
Non-Agency RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Borrowings	594,286
Fair Value of Collateral Pledged	797,784
Amortized Cost Of Collateral Pledged	785,952
Non-Agency RMBS \| Consolidated SLST \| VIE, Primary Beneficiary
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities owned and pledged as collateral, fair value	214,800
CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Borrowings	811,890
Fair Value of Collateral Pledged	1,036,513
Amortized Cost Of Collateral Pledged	853,043
CMBS \| Consolidated K-Series \| VIE, Primary Beneficiary
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities owned and pledged as collateral, fair value	$ 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
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
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-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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-Topic 235
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-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

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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
-Section 50
-Paragraph 1A
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-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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