Real Estate Securities - Trading Securities by Collateral Type (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Investment Holdings [Line Items]
Real estate securities, at fair value	$ 108,329	$ 170,619
Unpaid principal balance	215,592	235,306
Principal balance of securities acquired	0	50,180
Principal balance of securities sold	17,716	55,561
Net market valuation gains (losses) recorded	(34,221)	23,583
Securities bought and sold during the same quarter		5,000
Senior IO Securities
Investment Holdings [Line Items]
Real estate securities, at fair value	28,867	21,787
Unpaid principal balance	0	0
Subordinate
Investment Holdings [Line Items]
Real estate securities, at fair value	79,462	148,832
Unpaid principal balance	215,592	235,306
Interest-only securities \| Senior IO Securities
Investment Holdings [Line Items]
Real estate securities, at fair value	28,867	21,787
Interest-only securities \| Senior IO Securities \| Sequoia
Investment Holdings [Line Items]
Real estate securities, at fair value	26,000	15,000
RPL securities \| Subordinate
Investment Holdings [Line Items]
Real estate securities, at fair value	29,002	65,140
Multifamily securities \| Subordinate
Investment Holdings [Line Items]
Real estate securities, at fair value	5,027	10,549
Other third-party residential securities \| Subordinate
Investment Holdings [Line Items]
Real estate securities, at fair value	$ 45,433	$ 73,143

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Amount of increase (decrease) of investment in debt and equity securities, measured at fair value with changes in fair value recognized in net income.

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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.

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For investments which are quantified by principal amount, the principle balance held at close of period.

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The cash outflow to acquire securities classified as trading securities and held for investment purposes. Excludes payments for trading securities purchased and held principally for the purpose of selling them in the near term (thus held for only a short period of time).

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The cash inflow associated with the sale of securities classified as trading securities and held for investment purposes. Excludes proceeds from trading securities purchased and held principally for the purpose of selling them in the near term (thus held for only a short period of time).

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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