DERIVATIVES - Derivatives Gain (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative [Line Items]
Derivative instruments	$ 23,089	$ 41,389	$ 4,213	$ (25,037)
Gain (loss) on settlement of investments, net	(23,192)	(14,147)	(133,099)	(152,424)
Gain on originated mortgage loans, held-for-sale, net	76,006	17,119	182,672	23,049
Total income (losses)	75,903	44,361	53,786	(154,412)
Loss on settlement of mortgage loan origination derivative instruments	68,789	32,138	290,670	61,879
Interest rate caps
Derivative [Line Items]
Derivative instruments	0	0	0	(3)
Interest rate swaps
Derivative [Line Items]
Derivative instruments	23,089	42,306	4,213	(26,893)
Gain (loss) on settlement of investments, net	(23,192)	(10,338)	(62,039)	(32,529)
Interest rate lock commitments
Derivative [Line Items]
Gain on originated mortgage loans, held-for-sale, net	82,019	3,002	206,073	13,911
TBAs
Derivative [Line Items]
Derivative instruments	0	(917)	0	1,859
Gain (loss) on settlement of investments, net	0	(3,809)	(71,060)	(119,895)
Gain on originated mortgage loans, held-for-sale, net	(6,013)	14,389	(23,428)	9,208
Forward loan sale commitments
Derivative [Line Items]
Gain on originated mortgage loans, held-for-sale, net	$ 0	$ (272)	$ 27	$ (70)