OTHER INCOME (LOSS), GENERAL AND ADMINISTRATIVE, OTHER ASSETS AND LIABILITIES - Schedule of Change in Fair Value of Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other Income Assets And Liabilities
Excess mortgage servicing rights	$ (664)	$ 2,407	$ (11,773)	$ (1,421)
Excess mortgage servicing rights, equity method investees	(393)	4,751	(2,902)	4,087
Mortgage servicing rights financing receivables	(20,275)	(41,410)	(245,906)	(133,200)
Servicer advance investments	3,143	6,641	431	15,932
Real estate and other securities	27,663	(5,054)	(531)	9,010
Residential mortgage loans	56,940	(6,512)	(108,306)	75,095
Consumer loans held-for-investment	(411)	0	(9,634)	0
Derivative instruments	23,089	41,389	4,213	(25,037)
Change in fair value of investments	$ 89,092	$ 2,212	$ (374,408)	$ (55,534)