LOANS - Investment Loan Activity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning balance January 1, 2022	$ 4,242,043	[1],[2]
Ending balance September 30, 2022	1,551,707	[2]
Transfer of residential loans to securitization vehicles, carrying value, noncash	5,500,000
Total
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning balance January 1, 2022	4,241,063
Purchases / originations	5,193,659
Sales and transfers	(7,372,881)
Principal payments	(317,519)
Gains / (losses)	(189,431)
(Amortization) / accretion	(3,254)
Ending balance September 30, 2022	1,551,637
Residential
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning balance January 1, 2022	2,272,072
Purchases / originations	5,008,390
Sales and transfers	(5,470,437)
Principal payments	(86,329)
Gains / (losses)	(166,111)
(Amortization) / accretion	(5,948)
Ending balance September 30, 2022	1,551,637
Corporate Debt
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning balance January 1, 2022	1,968,991
Purchases / originations	185,269
Sales and transfers	(1,902,444)
Principal payments	(231,190)
Gains / (losses)	(23,320)
(Amortization) / accretion	2,694
Ending balance September 30, 2022	$ 0

[1] (1)Derived from the audited consolidated financial statements at December 31, 2021.

[2] (4)Includes $1.4 million and $2.3 million of residential mortgage loans held for sale at September 30, 2022 and December 31, 2021, respectively.