Loans Held for Investment and Loans Held for Investment at Fair Value - Summary of UPB and Amortized Cost Basis of Loans in COVID-19 Forbearance Program (Details) - COVID 19 Forbearance Program - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Accounts Notes And Loans Receivable [Line Items]
UPB Beginning balance	$ 201,005	$ 292,429
UPB Foreclosures	(99)	(3,593)
UPB Repayments	(5,792)	(87,831)
UPB Ending balance	195,114	201,005
UPB Performing/Accruing, Amount	156,374	161,455
UPB Nonperforming/Nonaccrual, Amount	$ 38,740	$ 39,550
UPB Performing/Accruing, Percentage	80.10%	80.30%
UPB Nonperforming/Nonaccrual, Percentage	19.90%	19.70%
Amortized Cost Beginning balance	$ 203,346	$ 295,990
Amortized Cost Foreclosures	(99)	(3,620)
Amortized Cost Repayments	(5,897)	(89,024)
Amortized Cost Ending balance	197,350	203,346
Amortized Cost Performing/Accruing, Amount	158,169	163,346
Amortized Cost Nonperforming/Nonaccrual, Amount	$ 39,181	$ 40,000
Amortized Cost Performing/Accruing, Percentage	80.10%	80.30%
Amortized Cost Nonperforming/Nonaccrual, Percentage	19.90%	19.70%