INVESTMENTS IN MORTGAGE SERVICING RIGHTS AND MORTGAGE SERVICING RIGHTS FINANCING RECEIVABLES - Narrative (Details) - USD ($) $ in Thousands														6 Months Ended	12 Months Ended
	Nov. 08, 2018	Aug. 31, 2018	Jun. 28, 2018	Jun. 04, 2018	Jun. 01, 2018	May 31, 2018	May 25, 2018	May 01, 2018	Mar. 28, 2018	Feb. 28, 2018	Jan. 18, 2018	Nov. 29, 2017	Jul. 23, 2017	Jun. 30, 2018	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of MSRs [Line Items]
UPB of Underlying Mortgages															$ 103,000,000
Payments to acquire mortgage servicing rights (MSR)	$ 1,500	$ 220,500	$ 66,500	$ 19,300	$ 6,100	$ 79,900	$ 26,300	$ 36,200	$ 96,600	$ 33,500					1,186,000
Residential mortgage loans subject to repurchase															121,602		$ 0	$ 0
Initial contract term (in years)													5 years
Contract extension term with thirty day notice (in months)													3 months
Ocwen
Schedule of MSRs [Line Items]
UPB of Underlying Mortgages																$ 86,800,000
Payments to acquire finance receivables											$ 279,600
MSRs
Schedule of MSRs [Line Items]
UPB of Underlying Mortgages	$ 100,000	$ 18,500,000	$ 4,700,000	$ 2,100,000	$ 500,000	$ 6,100,000	$ 2,100,000	$ 4,600,000	$ 8,100,000	$ 3,300,000
Mortgage Loans Subserviced
Schedule of MSRs [Line Items]
UPB of Underlying Mortgages															47,300,000
Subservicing revenue															$ 61,300
Nationstar
Schedule of MSRs [Line Items]
Subservicer percent of UPB															24.40%
Ocwen
Schedule of MSRs [Line Items]
Subservicer percent of UPB															22.70%
Ocwen | New Residential Mortgage LLC | MSRs
Schedule of MSRs [Line Items]
Payments to acquire mortgage servicing rights (MSR)															$ 334,200
Unpaid Principal Balance of underlying loans transferred															$ 36,100,000
Ditech Financial LLC
Schedule of MSRs [Line Items]
Subservicer percent of UPB															20.90%
PHH Mortgage Corporation
Schedule of MSRs [Line Items]
Subservicer percent of UPB															10.90%
LoanCare
Schedule of MSRs [Line Items]
Subservicer percent of UPB															1.60%
Flagstar
Schedule of MSRs [Line Items]
Subservicer percent of UPB															0.60%
ShellPoint | New Residential Mortgage LLC | MSRs
Schedule of MSRs [Line Items]
UPB of Underlying Mortgages												$ 7,800,000
Payments to acquire mortgage servicing rights (MSR)												$ 81,000
New Penn | MSRs
Schedule of MSRs [Line Items]
UPB of Underlying Mortgages														$ 11,400,000
Payments to acquire mortgage servicing rights (MSR)														$ 139,100
New Penn | New Residential Mortgage LLC | MSRs
Schedule of MSRs [Line Items]
Unpaid Principal Balance of underlying loans transferred															$ 20,600,000