LOANS - Investment Loan Activity (Details) $ in Thousands	6 Months Ended
	Jun. 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 June 30, 2022	1,487,133	[2]
Transfer of residential loans to securitization vehicles, carrying value, noncash	4,400,000
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	4,006,752
Sales and transfers	(6,352,699)
Principal payments	(298,152)
Gains / (losses)	(103,959)
(Amortization) / accretion	(6,194)
Ending balance June 30, 2022	1,486,811
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	3,821,483
Sales and transfers	(4,450,255)
Principal payments	(66,962)
Gains / (losses)	(80,639)
(Amortization) / accretion	(8,888)
Ending balance June 30, 2022	1,486,811
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 June 30, 2022	$ 0

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

[2] (4)Includes $1.5 million and $2.3 million of residential mortgage loans held for sale at June 30, 2022 and December 31, 2021, respectively.