DERIVATIVES - Derivatives Gain (Losses) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative [Line Items]
Servicing revenue, net	$ 0	$ (18,505,000)	$ 0	$ (11,316,000)
Gain on originated residential mortgage loans, held-for-sale, net	7,274,000	129,233,000	24,914,000	96,017,000
Realized and unrealized gains (losses) on investments, net	194,593,000	464,618,000	259,539,000	1,503,183,000
Total gain (loss)	201,867,000	575,346,000	284,453,000	1,587,884,000
Gain (loss) on settlement of residential mortgage loan	67,377,000	57,407,000	65,798,000	1,109,163,000
Servicing Revenue
Derivative [Line Items]
Gain (loss) on settlement of derivative instruments	0	(2,200,000)	0	(79,000,000)
TBAs
Derivative [Line Items]
Servicing revenue, net	0	(18,505,000)	0	(15,205,000)
Gain on originated residential mortgage loans, held-for-sale, net	15,574,000	233,673,000	28,803,000	250,661,000
Realized and unrealized gains (losses) on investments, net	3,066,000	(651,000)	(3,808,000)	357,987,000
Treasury futures
Derivative [Line Items]
Servicing revenue, net	0	0	0	(1,746,000)
Options on treasury futures
Derivative [Line Items]
Servicing revenue, net	0	0	0	5,635,000
Interest rate lock commitments
Derivative [Line Items]
Gain on originated residential mortgage loans, held-for-sale, net	(8,630,000)	(104,440,000)	(2,288,000)	(154,644,000)
Interest rate swaps
Derivative [Line Items]
Gain on originated residential mortgage loans, held-for-sale, net	330,000	0	(1,601,000)	0
Realized and unrealized gains (losses) on investments, net	$ 191,527,000	$ 465,269,000	$ 263,347,000	$ 1,145,196,000