Multifamily Loans (Details) - Multifamily loans, held-for-investment, at fair value $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) loan	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) loan
Redwood
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans | loan	28		28
Loan principal | $	$ 453,140		$ 455,168
Fair value of loans | $	$ 451,804		$ 473,514
Weighted average coupon rate (as a percent)	4.25%		4.25%
Contract maturities	3 years		4 years
Number of loans in foreclosure | loan	0		0
Redwood | Financing Receivables, Equal to Greater than 90 Days Past Due
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans with 90+ day delinquencies | loan	0		0
Held-for-investment at fair value
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Net market valuation gain (loss) | $	$ (19,681)	$ (730)