DEBT OBLIGATIONS - Schedule of Debt Obligations (Details) - USD ($)	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Outstanding Face Amount	$ 23,421,033,000
Carrying Value	$ 23,308,911,000	$ 29,237,694,000
Weighted Average Funding Cost	3.65%
Weighted Average Life (Years)	1 year 1 month 6 days
MSR purchase price holdback	$ 69,691,000	30,931,000
Secured Financing Agreements
Debt Instrument [Line Items]
Outstanding Face Amount	13,657,210,000
Carrying Value	$ 13,655,247,000	20,592,884,000
Weighted Average Funding Cost	3.42%
Weighted Average Life (Years)	3 months 18 days
MSR purchase price holdback	$ 54,000,000
Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	9,763,823,000
Carrying Value	$ 9,653,664,000	8,644,810,000
Weighted Average Funding Cost	3.96%
Weighted Average Life (Years)	2 years 3 months 18 days
Warehouse Credit Facilities-Residential Mortgage Loans | Warehouse Credit Facilities
Debt Instrument [Line Items]
Outstanding Face Amount	$ 3,743,336,000
Carrying Value	$ 3,741,373,000	10,296,812,000
Weighted Average Funding Cost	3.96%
Weighted Average Life (Years)	7 months 6 days
Repurchase agreements	$ 217,600,000
Interest rate	4.00%
Warehouse Credit Facilities-Residential Mortgage Loans | Warehouse Credit Facilities | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	21 years 4 months 24 days
Outstanding Face of Collateral	$ 4,454,467,000
Amortized Cost Basis of Collateral	4,260,857,000
Carrying Value of Collateral	4,112,852,000
Warehouse Credit Facilities - Mortgage Loans Receivable | Warehouse Credit Facilities
Debt Instrument [Line Items]
Outstanding Face Amount	1,077,413,000
Carrying Value	$ 1,077,413,000	1,252,660,000
Weighted Average Funding Cost	5.65%
Weighted Average Life (Years)	1 year
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	$ 1,283,193,000
Amortized Cost Basis of Collateral	1,283,193,000
Carrying Value of Collateral	1,283,193,000
Agency RMBS | Secured Financing Agreements
Debt Instrument [Line Items]
Outstanding Face Amount	8,224,352,000
Carrying Value	$ 8,224,352,000	8,386,538,000
Weighted Average Funding Cost	2.75%
Weighted Average Life (Years)	0 years
Agency RMBS | Secured Financing Agreements | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	9 years 10 months 24 days
Outstanding Face of Collateral	$ 8,598,313,000
Amortized Cost Basis of Collateral	8,582,299,000
Carrying Value of Collateral	8,482,906,000
Non-Agency RMBS | Secured Financing Agreements
Debt Instrument [Line Items]
Outstanding Face Amount	612,109,000
Carrying Value	$ 612,109,000	656,874,000
Weighted Average Funding Cost	5.11%
Weighted Average Life (Years)	10 months 24 days
Non-Agency RMBS | Secured Financing Agreements | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	5 years 1 month 6 days
Outstanding Face of Collateral	$ 14,626,707,000
Amortized Cost Basis of Collateral	930,056,000
Carrying Value of Collateral	926,339,000
SFR properties
Debt Instrument [Line Items]
Carrying Value	813,915,000	357,922,000
SFR properties | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	863,029,000
Carrying Value	$ 813,915,000	199,407,000
Weighted Average Funding Cost	3.60%
Weighted Average Life (Years)	4 years 2 months 12 days
SFR properties | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Amortized Cost Basis of Collateral	$ 941,715,000
Carrying Value of Collateral	941,715,000
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)	2 years 10 months 24 days
Excess MSRs | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	5 years 10 months 24 days
Outstanding Face of Collateral	$ 70,067,350,000
Amortized Cost Basis of Collateral	263,278,000
Carrying Value of Collateral	315,966,000
MSRs | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	4,574,995,000
Carrying Value	$ 4,566,704,000	4,234,771,000
Weighted Average Funding Cost	4.91%
Weighted Average Life (Years)	2 years 4 months 24 days
MSRs | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	7 years 1 month 6 days
Outstanding Face of Collateral	$ 536,226,491,000
Amortized Cost Basis of Collateral	6,764,622,000
Carrying Value of Collateral	8,839,634,000
Servicer Advance Investments | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	318,590,000
Carrying Value	$ 317,752,000	355,722,000
Weighted Average Funding Cost	1.23%
Weighted Average Life (Years)	3 months 18 days
Servicer Advance Investments | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	7 years 9 months 18 days
Outstanding Face of Collateral	$ 334,818,000
Amortized Cost Basis of Collateral	358,225,000
Carrying Value of Collateral	$ 371,418,000
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	$ 2,127,691,000
Carrying Value	$ 2,123,593,000	2,355,969,000
Weighted Average Funding Cost	3.16%
Weighted Average Life (Years)	1 year
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	$ 2,525,729,000
Amortized Cost Basis of Collateral	2,522,246,000
Carrying Value of Collateral	2,522,246,000
Residential Mortgage Loans | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	771,748,000
Carrying Value	$ 771,285,000	802,526,000
Weighted Average Funding Cost	2.17%
Weighted Average Life (Years)	2 years 1 month 6 days
Residential Mortgage Loans | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	28 years 2 months 12 days
Outstanding Face of Collateral	$ 789,890,000
Amortized Cost Basis of Collateral	799,997,000
Carrying Value of Collateral	799,997,000
Consumer Loans
Debt Instrument [Line Items]
Carrying Value	320,001,000	458,580,000
Consumer Loans | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	355,211,000
Carrying Value	$ 320,001,000	458,580,000
Weighted Average Funding Cost	2.07%
Weighted Average Life (Years)	3 years 3 months 18 days
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	$ 353,127,000
Amortized Cost Basis of Collateral	365,989,000
Carrying Value of Collateral	393,567,000
Mortgage Loans Receivable
Debt Instrument [Line Items]
Carrying Value	1,589,330,000	1,252,660,000
Mortgage Loans Receivable | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	524,062,000
Carrying Value	$ 511,917,000	$ 0
Weighted Average Funding Cost	5.17%
Weighted Average Life (Years)	4 years 1 month 6 days
Mortgage Loans Receivable | Secured Notes and Bonds Payable | Collateral
Debt Instrument [Line Items]
Weighted Average Life (Years)	7 months 6 days
Outstanding Face of Collateral	$ 576,851,000
Amortized Cost Basis of Collateral	576,851,000
Carrying Value of Collateral	576,851,000
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%
2.5% To 3.5% Agency MSR Secured Note And Bond Payable | Secured Notes and Bonds Payable
Debt Instrument [Line Items]
Outstanding Face Amount	$ 2,700,000,000
2.5% To 3.5% 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%
2.5% To 3.5% 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	$ 1,900,000,000
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	$ 21,800,000
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	$ 302,200,000
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