RESIDENTIAL MORTGAGE LOANS - Schedule of Aggregate Unpaid Principal Balance and Aggregate Carrying Value (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	$ 235,176	$ 290,180
Less than 120 | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	4,413,616	11,101,345
Notes receivable	4,303,086	11,323,443
Fair Value Over (Under) Unpaid Principal Balance	(110,530)	222,098
120 or greater | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	3,504,699	623,093
Notes receivable	3,446,793	594,335
Fair Value Over (Under) Unpaid Principal Balance	(57,906)	(28,758)
Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	234,648	289,065
Notes receivable	235,176	290,180
Fair Value Over (Under) Unpaid Principal Balance	528	1,115
Past Due | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	7,918,315	11,724,438
Notes receivable	7,749,879	11,917,778
Fair Value Over (Under) Unpaid Principal Balance	$ (168,436)	$ 193,340