Secured Financing Agreements - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2023	Dec. 31, 2022
Repurchase Agreement Counterparty [Line Items]
Repurchase agreements outstanding	$ 2,686,522	$ 3,434,765
Margin cash collateral pledged to repurchase agreement counterparties	$ 15,304	$ 33,415
Securities sold under agreements to repurchase, haircut	7.50%	7.50%
Decrease in share price (as a percent)	50.00%
Weighted average maturity	5 years
Securities sold under agreements to repurchase, weighted average borrowing rate	5.14%	5.14%
Nomura
Repurchase Agreement Counterparty [Line Items]
Amount at risk	$ 304,000	$ 308,000
Warehouse Agreement Borrowings
Repurchase Agreement Counterparty [Line Items]
Unused warehouse credit facilities	$ 2,100,000
Repurchase Agreements \| Nomura \| Stockholders' Equity, Total \| Credit Concentration Risk \| Asset Pledged as Collateral
Repurchase Agreement Counterparty [Line Items]
Concentration risk (as a percent)	12.00%	12.00%
Weighted average maturity	454 days	582 days
Minimum \| Warehouse Agreement Borrowings
Repurchase Agreement Counterparty [Line Items]
Maturity dates of credit facility	30 days
Maximum \| Warehouse Agreement Borrowings
Repurchase Agreement Counterparty [Line Items]
Maturity dates of credit facility	1 year
Not Subject to Additional Margin Requirements Upon Change in Fair Value of Collateral Pledged
Repurchase Agreement Counterparty [Line Items]
Repurchase agreements outstanding	$ 1,200,000	$ 1,200,000
Not Subject to Additional Margin Requirements Until Drop in Fair Value of Collateral
Repurchase Agreement Counterparty [Line Items]
Repurchase agreements outstanding	$ 316,000	$ 365,000
Agency RMBS - Interest-only
Repurchase Agreement Counterparty [Line Items]
Securities sold under agreements to repurchase, haircut		20.00%
Agency MBS - Commercial
Repurchase Agreement Counterparty [Line Items]
Securities sold under agreements to repurchase, haircut	5.10%	7.80%
Non-agency MBS and Loans held for investment
Repurchase Agreement Counterparty [Line Items]
Securities sold under agreements to repurchase, haircut	25.10%	25.70%
Secured Financing Agreements, at fair value
Repurchase Agreement Counterparty [Line Items]
Repurchase agreements outstanding	$ 374,929	$ 382,838
Secured financing agreements	353,817	374,172
Fair value of pledged collateral	$ 414,000	$ 418,000

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Securities Sold under Agreements to Repurchase, Margin

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Average rate paid on securities sold under agreements to repurchase.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

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Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The amount at risk under repurchase agreements is defined as the excess of carrying amount (or market value, if higher than the carrying amount or if there is no carrying amount) of the securities or other assets sold under agreement to repurchase, including accrued interest plus any cash or other assets on deposit to secure the repurchase obligation, over the amount of the repurchase liability (adjusted for accrued interest).

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Weighted average maturity (weighted by amount of the agreement) of repurchase agreements with the counterparty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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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.

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Amount of right to receive cash collateral under master netting arrangements that have not been offset against securities sold under agreement to repurchase.

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Fair value of securities pledged as collateral against securities sold under agreement to repurchase.

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