OTHER INCOME (LOSS), GENERAL AND ADMINISTRATIVE, OTHER ASSETS AND LIABILITIES - Schedule of Accretion and Other Amortization (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accretion and other amortization:
Accretion of net discount on securities and loans	$ 81,112	$ 266,467
Accretion of servicer advances receivable discount and servicer advance investments	38,967	18,290
Accretion of excess mortgage servicing rights income	25,177	18,203
Amortization of deferred financing costs	(12,352)	(2,984)
Accretion of loan discount and premium amortization, net	127,456	298,933
Secured Notes and Bonds Payable
Accretion and other amortization:
Amortization of discount on secured notes and bonds payable	(379)	(1,043)
Term Loan
Accretion and other amortization:
Amortization of discount on secured notes and bonds payable	$ (5,069)	$ 0