Loans Held for Investment - Changes in Carrying Value of Securitized Loans Held For Investment Carried at Fair Value (Details) - Loans Held for Investment at Fair Value - Variable Interest Entities, Primary Beneficiary - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance, beginning of period	$ 12,261,926	$ 13,112,129	$ 13,112,129
Transfer due to consolidation	1,047,838	$ 0	0
Purchases	1,625,222		3,364,609
Principal paydowns	(1,764,067)		(2,652,767)
Sales and settlements	(3,586)		(1,679,280)
Net periodic accretion (amortization)	(57,434)		(79,368)
Change in fair value	(1,402,600)		196,603
Balance, end of period	$ 11,707,299		$ 12,261,926