Real Estate Securities - Available for Sale Securities by Collateral Type (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Investment Holdings [Line Items]
Available-for-sale	$ 134,980		$ 132,146
Fair value of securities acquired	0	$ 10,000
Fair value of securities sold	2,678	0
Principal balance of securities called	0	14,486
Net unrealized gain (loss) on available-for-sale securities	5,007	$ (17,873)
Sequoia securities
Investment Holdings [Line Items]
Available-for-sale	77,714		74,367
Consolidated Agency multifamily loans, at fair value
Investment Holdings [Line Items]
Available-for-sale	7,670		7,647
Other third-party residential securities
Investment Holdings [Line Items]
Available-for-sale	49,596		50,132
Total Subordinate Investment Securities
Investment Holdings [Line Items]
Available-for-sale	$ 134,980		$ 132,146

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