DEBT OBLIGATIONS - Schedule of Debt Obligations (Details) - USD ($)	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Outstanding Face Amount	$ 23,340,461,000
Carrying Value	$ 23,289,260,000	$ 29,237,694,000
Weighted Average Funding Cost	2.84%
Weighted Average Life (Years)	1 year 3 months 18 days
MSR purchase price holdback	$ 40,586,000	30,931,000
Secured Financing Agreements
Debt Instrument [Line Items]
Outstanding Face Amount	13,969,519,000
Carrying Value	$ 13,967,234,000	20,592,884,000
Weighted Average Funding Cost	2.21%
Weighted Average Life (Years)	4 months 24 days
MSR purchase price holdback	$ 23,500,000
Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	9,370,942,000
Carrying Value	$ 9,322,026,000	8,644,810,000
Weighted Average Funding Cost	3.75%
Weighted Average Life (Years)	2 years 7 months 6 days
Warehouse Credit Facilities-Residential Mortgage Loans | Warehouse Credit Facilities
Debt Instrument [Line Items]
Outstanding Face Amount	$ 4,910,944,000
Carrying Value	$ 4,908,659,000	10,138,297,000
Weighted Average Funding Cost	3.05%
Weighted Average Life (Years)	8 months 12 days
Repurchase agreements	$ 227,900,000
Interest rate	4.00%
Warehouse Credit Facilities-Residential Mortgage Loans | Warehouse Credit Facilities | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	20 years 3 months 18 days
Outstanding Face of Collateral	$ 5,646,909,000
Amortized Cost Basis of Collateral	5,588,006,000
Carrying Value of Collateral	5,479,872,000
Warehouse Credit Facilities - Mortgage Loans Receivable | Warehouse Credit Facilities
Debt Instrument [Line Items]
Outstanding Face Amount	1,161,223,000
Carrying Value	$ 1,161,223,000	1,252,660,000
Weighted Average Funding Cost	3.93%
Weighted Average Life (Years)	1 year 6 months
Warehouse Credit Facilities - Mortgage Loans Receivable | Warehouse Credit Facilities | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	8 months 12 days
Outstanding Face of Collateral	$ 1,358,294,000
Amortized Cost Basis of Collateral	1,358,294,000
Carrying Value of Collateral	1,358,294,000
Agency RMBS | Secured Financing Agreements
Debt Instrument [Line Items]
Outstanding Face Amount	7,040,807,000
Carrying Value	$ 7,040,807,000	8,386,538,000
Weighted Average Funding Cost	1.18%
Weighted Average Life (Years)	1 month 6 days
Agency RMBS | Secured Financing Agreements | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	9 years 7 months 6 days
Outstanding Face of Collateral	$ 7,994,763,000
Amortized Cost Basis of Collateral	8,216,954,000
Carrying Value of Collateral	7,061,674,000
Non-Agency RMBS | Secured Financing Agreements
Debt Instrument [Line Items]
Outstanding Face Amount	621,058,000
Carrying Value	$ 621,058,000	656,874,000
Weighted Average Funding Cost	3.73%
Weighted Average Life (Years)	1 month 6 days
Non-Agency RMBS | Secured Financing Agreements | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	3 years 8 months 12 days
Outstanding Face of Collateral	$ 13,777,282,000
Amortized Cost Basis of Collateral	886,905,000
Carrying Value of Collateral	884,604,000
SFR properties
Debt Instrument [Line Items]
Carrying Value	732,258,000	357,922,000
SFR properties | Secured Financing Agreements
Debt Instrument [Line Items]
Outstanding Face Amount	235,487,000
Carrying Value	$ 235,487,000	158,515,000
Weighted Average Funding Cost	3.15%
Weighted Average Life (Years)	6 months
SFR properties | Secured Financing Agreements | Collateral
Debt Instrument [Line Items]
Amortized Cost Basis of Collateral	$ 330,159,000
Carrying Value of Collateral	330,159,000
SFR properties | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	497,303,000
Carrying Value	$ 496,771,000	199,407,000
Weighted Average Funding Cost	3.59%
Weighted Average Life (Years)	3 years 7 months 6 days
SFR properties | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Amortized Cost Basis of Collateral	$ 542,385,000
Carrying Value of Collateral	542,385,000
Excess MSRs
Debt Instrument [Line Items]
Carrying Value	228,497,000	237,835,000
Excess MSRs | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	228,497,000
Carrying Value	$ 228,497,000	237,835,000
Weighted Average Funding Cost	3.74%
Weighted Average Life (Years)	3 years 1 month 6 days
Excess MSRs | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	6 years 9 months 18 days
Outstanding Face of Collateral	$ 73,121,546,000
Amortized Cost Basis of Collateral	265,354,000
Carrying Value of Collateral	329,535,000
MSRs | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	4,666,798,000
Carrying Value	$ 4,657,497,000	4,234,771,000
Weighted Average Funding Cost	4.60%
Weighted Average Life (Years)	2 years 8 months 12 days
MSRs | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	7 years 6 months
Outstanding Face of Collateral	$ 527,279,143,000
Amortized Cost Basis of Collateral	6,414,614,000
Carrying Value of Collateral	8,279,291,000
Servicer Advance Investments | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	322,735,000
Carrying Value	$ 321,891,000	355,722,000
Weighted Average Funding Cost	1.22%
Weighted Average Life (Years)	6 months
Servicer Advance Investments | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	7 years 6 months
Outstanding Face of Collateral	$ 341,328,000
Amortized Cost Basis of Collateral	365,677,000
Carrying Value of Collateral	$ 379,901,000
Servicer Advances | Secured Notes and Bonds Payable | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Variable interest rate spread	1.10%
Servicer Advances | Secured Notes and Bonds Payable | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Variable interest rate spread	3.50%
Servicer Advances | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	$ 2,174,064,000
Carrying Value	$ 2,169,295,000	2,355,969,000
Weighted Average Funding Cost	3.08%
Weighted Average Life (Years)	1 year 2 months 12 days
Face amount of debt at fixed rate	$ 1,700,000,000
Servicer Advances | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	8 months 12 days
Outstanding Face of Collateral	$ 2,590,339,000
Amortized Cost Basis of Collateral	2,560,696,000
Carrying Value of Collateral	2,560,696,000
Residential Mortgage Loans | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	772,887,000
Carrying Value	$ 772,998,000	802,526,000
Weighted Average Funding Cost	2.17%
Weighted Average Life (Years)	2 years 4 months 24 days
Residential Mortgage Loans | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	26 years 9 months 18 days
Outstanding Face of Collateral	$ 791,041,000
Amortized Cost Basis of Collateral	796,987,000
Carrying Value of Collateral	796,987,000
Consumer Loans
Debt Instrument [Line Items]
Carrying Value	357,663,000	458,580,000
Consumer Loans | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	384,596,000
Carrying Value	$ 357,663,000	458,580,000
Weighted Average Funding Cost	2.07%
Weighted Average Life (Years)	8 years
Consumer Loans | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	3 years 3 months 18 days
Outstanding Face of Collateral	$ 380,549,000
Amortized Cost Basis of Collateral	393,138,000
Carrying Value of Collateral	423,704,000
Mortgage Loans Receivable
Debt Instrument [Line Items]
Carrying Value	1,478,637,000	1,252,660,000
Mortgage Loans Receivable | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	324,062,000
Carrying Value	$ 317,414,000	$ 0
Weighted Average Funding Cost	4.43%
Weighted Average Life (Years)	4 years 6 months
Mortgage Loans Receivable | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	8 months 12 days
Outstanding Face of Collateral	$ 352,867,000
Amortized Cost Basis of Collateral	352,867,000
Carrying Value of Collateral	352,867,000
3.7% Secured Corporate Note | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	$ 228,500,000
3.7% Secured Corporate Note | Secured Notes and Bonds Payable | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate spread	3.70%
2.8% To 4.5% Agency MSR Secured Note And Bond Payable | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	$ 2,600,000,000
2.8% To 4.5% Agency MSR Secured Note And Bond Payable | Secured Notes and Bonds Payable | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Variable interest rate spread	2.50%
2.8% To 4.5% Agency MSR Secured Note And Bond Payable | Secured Notes and Bonds Payable | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Variable interest rate spread	3.50%
3.0% To 5.4% Public Notes | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	$ 2,000,000,000
3.0% To 5.4% Public Notes | Secured Notes and Bonds Payable | Minimum
Debt Instrument [Line Items]
Interest rate	3.00%
3.0% To 5.4% Public Notes | Secured Notes and Bonds Payable | Maximum
Debt Instrument [Line Items]
Interest rate	5.40%
3.8% Asset-Backed Notes | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	$ 22,900,000
3.8% Asset-Backed Notes | Secured Notes and Bonds Payable | Maximum
Debt Instrument [Line Items]
Weighted Average Funding Cost	3.80%
Revolving Warehouse Facility Backed Notes | Secured Notes and Bonds Payable | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate spread	1.10%
Revolving Warehouse Facility Backed Notes | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	$ 750,000,000
Consumer Loan, UPB Class A | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Interest rate	2.00%
Residential mortgage loan UPB and other collateral	$ 331,600,000
Consumer Loan, UPB Class B | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Interest rate	2.70%
Residential mortgage loan UPB and other collateral	$ 53,000,000