INVESTMENTS IN EXCESS MORTGAGE SERVICING RIGHTS ASSETS - Summary of Direct Investments in Excess MSRs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Weighted Average Life (Years)			1 year 2 months 12 days
Carrying Value	$ 5,021,086		$ 5,021,086		$ 5,686,233
Servicer Advance Investments | Servicer Advances
Schedule of Equity Method Investments [Line Items]
UPB of Underlying Mortgages	28,834,119		28,834,119		31,442,267
Original and Recaptured Pools
Schedule of Equity Method Investments [Line Items]
Original and Recaptured Pools	(85)	$ (8,455)	(11,109)	$ (3,828)
Excess MSRs
Schedule of Equity Method Investments [Line Items]
UPB of Underlying Mortgages	81,666,625		$ 81,666,625
Weighted Average Life (Years)			6 years 1 month 6 days
Servicing Asset at Amortized Cost	281,290		$ 281,290
Carrying Value	346,450		346,450		379,747
Excess MSRs | Mr. Cooper
Schedule of Equity Method Investments [Line Items]
Carrying Value	344,515		344,515		377,692
Excess MSRs | Original and Recaptured Pools | Original and Recaptured Pools
Schedule of Equity Method Investments [Line Items]
UPB of Underlying Mortgages	39,833,663		$ 39,833,663
Weighted Average Life (Years)			5 years 9 months 18 days
Servicing Asset at Amortized Cost	162,415		$ 162,415
Carrying Value	$ 186,928		$ 186,928		209,633
Excess MSRs | Original and Recaptured Pools | Original and Recaptured Pools | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	32.50%		32.50%
Excess MSRs | Original and Recaptured Pools | Original and Recaptured Pools | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	66.70%		66.70%
Excess MSRs | Original and Recaptured Pools | Original and Recaptured Pools | Weighted Average
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	53.30%		53.30%
Excess MSRs | Original and Recaptured Pools | Recapture Agreement | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	32.50%		32.50%
Excess MSRs | Original and Recaptured Pools | Recapture Agreement | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	66.70%		66.70%
Excess MSRs | Original and Recaptured Pools | Recapture Agreement | Weighted Average
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	53.30%		53.30%
Excess MSRs | Original and Recaptured Pools | Fortress-managed funds | Original and Recaptured Pools | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	0.00%		0.00%
Excess MSRs | Original and Recaptured Pools | Fortress-managed funds | Original and Recaptured Pools | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	40.00%		40.00%
Excess MSRs | Original and Recaptured Pools | Fortress-managed funds | Recapture Agreement | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	20.00%		20.00%
Excess MSRs | Original and Recaptured Pools | Fortress-managed funds | Recapture Agreement | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	35.00%		35.00%
Excess MSRs | Original and Recaptured Pools | Mr. Cooper | Original and Recaptured Pools | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	20.00%		20.00%
Excess MSRs | Original and Recaptured Pools | Mr. Cooper | Original and Recaptured Pools | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	35.00%		35.00%
Excess MSRs | Original and Recaptured Pools | Mr. Cooper | Recapture Agreement | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	20.00%		20.00%
Excess MSRs | Original and Recaptured Pools | Mr. Cooper | Recapture Agreement | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	35.00%		35.00%
Excess MSRs | Non-Agency | Original and Recaptured Pools
Schedule of Equity Method Investments [Line Items]
UPB of Underlying Mortgages	$ 41,832,962		$ 41,832,962
Weighted Average Life (Years)			6 years 6 months
Servicing Asset at Amortized Cost	118,875		$ 118,875
Carrying Value	$ 159,522		$ 159,522		$ 170,114
Excess MSRs | Non-Agency | Original and Recaptured Pools | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	33.30%		33.30%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	100.00%		100.00%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Weighted Average
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	59.40%		59.40%
Excess MSRs | Non-Agency | Recapture Agreement | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	33.30%		33.30%
Excess MSRs | Non-Agency | Recapture Agreement | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	100.00%		100.00%
Excess MSRs | Non-Agency | Recapture Agreement | Weighted Average
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	59.40%		59.40%
Excess MSRs | Non-Agency | Fortress-managed funds | Original and Recaptured Pools | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	0.00%		0.00%
Excess MSRs | Non-Agency | Fortress-managed funds | Original and Recaptured Pools | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	50.00%		50.00%
Excess MSRs | Non-Agency | Fortress-managed funds | Recapture Agreement | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	0.00%		0.00%
Excess MSRs | Non-Agency | Fortress-managed funds | Recapture Agreement | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	33.30%		33.30%
Excess MSRs | Non-Agency | Mr. Cooper | Original and Recaptured Pools | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	0.00%		0.00%
Excess MSRs | Non-Agency | Mr. Cooper | Original and Recaptured Pools | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	33.30%		33.30%
Excess MSRs | Non-Agency | Mr. Cooper | Recapture Agreement | Minimum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	0.00%		0.00%
Excess MSRs | Non-Agency | Mr. Cooper | Recapture Agreement | Maximum
Schedule of Equity Method Investments [Line Items]
Interest in Excess MSR	33.30%		33.30%