INVESTMENTS IN EXCESS MORTGAGE SERVICING RIGHTS - Summary of Investments in Excess MSRs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment [Line Items]
Weighted Average Life (Years)	1 year 2 months 2 days
Changes in fair value recorded in other income	$ 4,322	$ (7,297)	$ 38,643
Corporate Joint Venture | Servicer Advance Bonds
Investment [Line Items]
UPB of Underlying Mortgages	139,460,371	186,362,657
Original and Recaptured Pools
Investment [Line Items]
Changes in fair value recorded in other income	(5,630)	(11,221)	34,936
Recapture Agreements
Investment [Line Items]
Changes in fair value recorded in other income	9,952	3,924	3,707
Excess MSRs
Investment [Line Items]
UPB of Underlying Mortgages	$ 217,121,299	$ 277,975,997
Weighted Average Life (Years)	6 years 3 months 18 days	6 years 4 months 24 days
Amortized Cost Basis	$ 1,028,523	$ 1,258,588
Carrying Value	1,173,713	1,399,455	1,581,517
Excess MSRs | Nationstar
Investment [Line Items]
Carrying Value	532,233	611,293	$ 698,304
Excess MSRs | Agency
Investment [Line Items]
UPB of Underlying Mortgages	$ 63,839,281	$ 78,295,454
Weighted Average Life (Years)	6 years 2 months 12 days	6 years 4 months 24 days
Amortized Cost Basis	$ 267,947	$ 322,032
Carrying Value	324,636	381,757
Excess MSRs | Agency | Original and Recaptured Pools
Investment [Line Items]
UPB of Underlying Mortgages	$ 63,839,281	$ 78,295,454
Weighted Average Life (Years)	5 years 9 months 18 days	5 years 10 months 24 days
Amortized Cost Basis	$ 249,003	$ 296,508
Carrying Value	$ 280,033	$ 330,323
Excess MSRs | Agency | Original and Recaptured Pools | Minimum
Investment [Line Items]
Interest in Excess MSR	32.50%	32.50%
Excess MSRs | Agency | Original and Recaptured Pools | Maximum
Investment [Line Items]
Interest in Excess MSR	66.70%	66.70%
Excess MSRs | Agency | Original and Recaptured Pools | Weighted Average
Investment [Line Items]
Interest in Excess MSR	53.50%	53.30%
Excess MSRs | Agency | Original and Recaptured Pools | Fortress-managed funds | Minimum
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%
Excess MSRs | Agency | Original and Recaptured Pools | Fortress-managed funds | Maximum
Investment [Line Items]
Interest in Excess MSR	40.00%	40.00%
Excess MSRs | Agency | Original and Recaptured Pools | Nationstar | Minimum
Investment [Line Items]
Interest in Excess MSR	20.00%	20.00%
Excess MSRs | Agency | Original and Recaptured Pools | Nationstar | Maximum
Investment [Line Items]
Interest in Excess MSR	35.00%	35.00%
Excess MSRs | Agency | Recapture Agreements
Investment [Line Items]
UPB of Underlying Mortgages	$ 0	$ 0
Weighted Average Life (Years)	11 years 4 months 24 days	12 years 3 months 18 days
Amortized Cost Basis	$ 18,944	$ 25,524
Carrying Value	$ 44,603	$ 51,434
Excess MSRs | Agency | Recapture Agreements | Minimum
Investment [Line Items]
Interest in Excess MSR	32.50%	32.50%
Excess MSRs | Agency | Recapture Agreements | Maximum
Investment [Line Items]
Interest in Excess MSR	66.70%	66.70%
Excess MSRs | Agency | Recapture Agreements | Weighted Average
Investment [Line Items]
Interest in Excess MSR	53.50%	53.30%
Excess MSRs | Agency | Recapture Agreements | Fortress-managed funds | Minimum
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%
Excess MSRs | Agency | Recapture Agreements | Fortress-managed funds | Maximum
Investment [Line Items]
Interest in Excess MSR	40.00%	40.00%
Excess MSRs | Agency | Recapture Agreements | Nationstar | Minimum
Investment [Line Items]
Interest in Excess MSR	20.00%	20.00%
Excess MSRs | Agency | Recapture Agreements | Nationstar | Maximum
Investment [Line Items]
Interest in Excess MSR	35.00%	35.00%
Excess MSRs | Non-Agency
Investment [Line Items]
UPB of Underlying Mortgages	$ 153,282,018	$ 199,680,543
Weighted Average Life (Years)	6 years 3 months 18 days	6 years 4 months 24 days
Amortized Cost Basis	$ 760,576	$ 936,556
Carrying Value	849,077	1,017,698
Excess MSRs | Non-Agency | Original and Recaptured Pools
Investment [Line Items]
UPB of Underlying Mortgages	$ 64,146,430	$ 78,209,375
Weighted Average Life (Years)	5 years 4 months 24 days	5 years 2 months 12 days
Amortized Cost Basis	$ 154,938	$ 183,775
Carrying Value	$ 190,696	$ 219,980
Excess MSRs | Non-Agency | Original and Recaptured Pools | Minimum
Investment [Line Items]
Interest in Excess MSR	33.30%	33.30%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Maximum
Investment [Line Items]
Interest in Excess MSR	100.00%	100.00%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Weighted Average
Investment [Line Items]
Interest in Excess MSR	59.60%	59.40%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Fortress-managed funds | Minimum
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Fortress-managed funds | Maximum
Investment [Line Items]
Interest in Excess MSR	50.00%	50.00%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Nationstar | Minimum
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%
Excess MSRs | Non-Agency | Original and Recaptured Pools | Nationstar | Maximum
Investment [Line Items]
Interest in Excess MSR	33.30%	33.30%
Excess MSRs | Non-Agency | Recapture Agreements
Investment [Line Items]
UPB of Underlying Mortgages	$ 0	$ 0
Weighted Average Life (Years)	11 years 3 months 18 days	12 years 2 months 12 days
Amortized Cost Basis	$ 7,489	$ 11,370
Carrying Value	$ 19,814	$ 13,491
Excess MSRs | Non-Agency | Recapture Agreements | Minimum
Investment [Line Items]
Interest in Excess MSR	33.30%	33.30%
Excess MSRs | Non-Agency | Recapture Agreements | Maximum
Investment [Line Items]
Interest in Excess MSR	100.00%	100.00%
Excess MSRs | Non-Agency | Recapture Agreements | Weighted Average
Investment [Line Items]
Interest in Excess MSR	59.60%	59.40%
Excess MSRs | Non-Agency | Recapture Agreements | Fortress-managed funds | Minimum
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%
Excess MSRs | Non-Agency | Recapture Agreements | Fortress-managed funds | Maximum
Investment [Line Items]
Interest in Excess MSR	50.00%	50.00%
Excess MSRs | Non-Agency | Recapture Agreements | Nationstar | Minimum
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%
Excess MSRs | Non-Agency | Recapture Agreements | Nationstar | Maximum
Investment [Line Items]
Interest in Excess MSR	33.30%	33.30%
Excess MSRs | Non-Agency | Ocwen Serviced Pools
Investment [Line Items]
UPB of Underlying Mortgages	$ 89,135,588	$ 121,471,168
Interest in Excess MSR	100.00%	100.00%
Weighted Average Life (Years)	6 years 6 months	6 years 7 months 6 days
Amortized Cost Basis	$ 598,149	$ 741,411
Carrying Value	$ 638,567	$ 784,227
Excess MSRs | Non-Agency | Ocwen Serviced Pools | Fortress-managed funds
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%
Excess MSRs | Non-Agency | Ocwen Serviced Pools | Nationstar
Investment [Line Items]
Interest in Excess MSR	0.00%	0.00%