SERVICER ADVANCE INVESTMENTS - Schedule of Interest Income Related to Investments in Servicer Advances (Details) - Servicer Advance Investments - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Interest income, gross of amounts attributable to servicer compensation	$ 83,807	$ 871,506	$ 922,006
Amounts attributable to base servicer compensation	(8,491)	(227,585)	(127,631)
Amounts attributable to incentive servicer compensation	(25,098)	(115,565)	(430,025)
Interest income from Servicer Advance Investments	$ 50,218	$ 528,356	$ 364,350