Residential Loans, at Fair Value - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Net realized gain (loss) on payoff and sale of mortgage loans	$ 10,000,000	$ 18,800,000	$ 9,700,000
Gain (loss) on sale of residential loans	0	(1,600,000)	$ 18,100,000
Principal outstanding	303,157,000
90 + | Residential loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal outstanding	159,981,000	102,981,000
90 + | VIE, Primary Beneficiary | Residential loans | Consolidated SLST
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 143,200,000	$ 135,900,000