Real Estate Securities - Available for Sale Securities by Collateral Type (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investment Holdings [Line Items]
Debt securities, available for sale	$ 132,146	$ 206,792
Fair value of securities acquired	10,000	19,100
Fair value of securities sold	0	4,785
Principal balance of securities called	20,267	27,875
Net unrealized (loss) gain on available-for-sale securities	(64,704)	8,016	$ (3,951)
Sequoia securities
Investment Holdings [Line Items]
Debt securities, available for sale	74,367	127,542
Multifamily securities
Investment Holdings [Line Items]
Debt securities, available for sale	7,647	22,166
Other third-party residential securities
Investment Holdings [Line Items]
Debt securities, available for sale	50,132	57,084
Total Subordinate
Investment Holdings [Line Items]
Debt securities, available for sale	$ 132,146	$ 206,792

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