FAIR VALUE MEASUREMENT - Narrative (Details) $ in Millions		9 Months Ended
	Apr. 10, 2020 USD ($)	Sep. 30, 2020 USD ($)	Aug. 31, 2019 USD ($) earnout_payment
Fair Value, Measurements, Nonrecurring
Schedule of Equity Method Investments [Line Items]
Assets, fair value		$ 602.7
Minimum
Schedule of Equity Method Investments [Line Items]
Broker price discount		10.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Broker price discount		25.00%
Weighted Average
Schedule of Equity Method Investments [Line Items]
Broker price discount		17.00%
Residential Mortgage Loans, Held-for-Sale | Fair Value, Measurements, Nonrecurring
Schedule of Equity Method Investments [Line Items]
Assets, fair value		$ 572.5
Real Estate Acquired in Satisfaction of Debt | Fair Value, Measurements, Nonrecurring
Schedule of Equity Method Investments [Line Items]
Assets, fair value		30.2
Residential mortgage loans, held-for-sale, at fair value
Schedule of Equity Method Investments [Line Items]
Asset fair value adjustment		121.1
Real Estate Owned
Schedule of Equity Method Investments [Line Items]
Asset fair value adjustment		$ (2.6)
Excess MSRs Investees | Minimum
Schedule of Equity Method Investments [Line Items]
Discount rate		7.50%
Excess MSRs Investees | Maximum
Schedule of Equity Method Investments [Line Items]
Discount rate		8.00%
Excess MSRs Investees | Weighted Average
Schedule of Equity Method Investments [Line Items]
Discount rate		7.80%
Mortgage Servicing Rights Financing Receivable
Schedule of Equity Method Investments [Line Items]
Discount rate		9.40%
Mortgage Servicing Rights Financing Receivable | Minimum
Schedule of Equity Method Investments [Line Items]
Discount rate		7.40%
Mortgage Servicing Rights Financing Receivable | Maximum
Schedule of Equity Method Investments [Line Items]
Discount rate		9.50%
Mortgage Servicing Rights Financing Receivable | Weighted Average
Schedule of Equity Method Investments [Line Items]
Discount rate		9.40%
MSRs
Schedule of Equity Method Investments [Line Items]
Discount rate		7.70%
MSRs | Minimum
Schedule of Equity Method Investments [Line Items]
Discount rate		7.40%
MSRs | Maximum
Schedule of Equity Method Investments [Line Items]
Discount rate		13.00%
MSRs | Weighted Average
Schedule of Equity Method Investments [Line Items]
Discount rate		7.70%
MSRs | Excess MSRs Investees
Schedule of Equity Method Investments [Line Items]
Discount rate		7.80%
London Interbank Offered Rate (LIBOR) | Mortgage Servicing Rights Financing Receivable
Schedule of Equity Method Investments [Line Items]
Variable interest rate spread		2.10%
Guardian Asset Management
Schedule of Equity Method Investments [Line Items]
Cash earnout payments | earnout_payment			4
Contingent consideration, discount rate		11.00%
NRZ Guardian Purchaser LLC | Guardian Asset Management
Schedule of Equity Method Investments [Line Items]
Contingent consideration			$ 17.5
Cash consideration transferred	$ 1.9