Indebtedness - Advance and Warehouse Facilities Summary (Details) - USD ($)	Jun. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Advance, warehouse and MSR facilities, net	$ 4,925,000,000	$ 4,302,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount	350,000,000
Outstanding	125,000,000	132,000,000
Collateral Pledged	159,000,000	169,000,000
Advance Facilities | Servicing | Loans payable | $300 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount	300,000,000
Outstanding	217,000,000	273,000,000
Collateral Pledged	217,000,000	364,000,000
Advance Facilities | Servicing | Loans payable | $300 advance facility(2)
Debt Instrument [Line Items]
Capacity Amount	300,000,000
Outstanding	251,000,000	250,000,000
Collateral Pledged	283,000,000	326,000,000
Advance Facilities | Servicing | Loans payable | $50 advance facility(3)
Debt Instrument [Line Items]
Capacity Amount	50,000,000
Outstanding	27,000,000	27,000,000
Collateral Pledged	43,000,000	49,000,000
Advance Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding	620,000,000	682,000,000
Collateral Pledged	702,000,000	908,000,000
Advance Facilities | Servicing | Notes payable to banks | $50 advance facility(3)
Debt Instrument [Line Items]
Capacity Amount	50,000,000
Warehouse Facilities | Originations | Notes payable to banks
Debt Instrument [Line Items]
Outstanding	1,369,000,000	822,000,000
Collateral Pledged	1,479,000,000	915,000,000
Warehouse Facilities | Originations | Notes payable to banks | $300 advance facility(2)
Debt Instrument [Line Items]
Capacity Amount	300,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,500,000,000
Outstanding	160,000,000	107,000,000
Collateral Pledged	160,000,000	104,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Outstanding	169,000,000	137,000,000
Collateral Pledged	209,000,000	176,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Outstanding	329,000,000	155,000,000
Collateral Pledged	351,000,000	166,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	118,000,000	72,000,000
Collateral Pledged	122,000,000	78,000,000
Warehouse Facilities | Originations | Notes payable to banks | $350 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	350,000,000
Outstanding	198,000,000	73,000,000
Collateral Pledged	202,000,000	75,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 warehouse facility(4)
Debt Instrument [Line Items]
Capacity Amount	250,000,000
Outstanding	220,000,000	158,000,000
Collateral Pledged	250,000,000	177,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	200,000,000
Outstanding	70,000,000	82,000,000
Collateral Pledged	73,000,000	84,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	200,000,000
Outstanding	0	12,000,000
Collateral Pledged	0	21,000,000
Warehouse Facilities | Originations | Notes payable to banks | $100 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	100,000,000
Outstanding	78,000,000	25,000,000
Collateral Pledged	85,000,000	33,000,000
Warehouse Facilities | Originations | Notes payable to banks | $100 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	100,000,000
Outstanding	0	0
Collateral Pledged	0	0
Warehouse Facilities | Originations | Notes payable to banks | $100 warehouse facility (3)
Debt Instrument [Line Items]
Capacity Amount	100,000,000
Outstanding	27,000,000	1,000,000
Collateral Pledged	27,000,000	1,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,000,000
Outstanding	0	0
Collateral Pledged	0	0
Warehouse Facilities | Originations | Notes payable to banks | $1,750 warehouse facility(5)
Debt Instrument [Line Items]
Capacity Amount	1,750,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,200,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 Advance Facility
Debt Instrument [Line Items]
Capacity Amount	250,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1500 million MSR facility
Debt Instrument [Line Items]
Capacity Amount	1,500,000,000
MSR Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding	2,950,000,000	2,814,000,000
Collateral Pledged	9,423,000,000	6,958,000,000
MSR Facilities | Servicing | Notes payable to banks | $1750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,750,000,000
MSR Facilities | Servicing | Notes payable to banks | $950 million MSR facility
Debt Instrument [Line Items]
Capacity Amount	950,000,000
Outstanding	680,000,000	300,000,000
Collateral Pledged	1,634,000,000	2,164,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,750 warehouse facility(5)
Debt Instrument [Line Items]
Capacity Amount	1,750,000,000
Outstanding	900,000,000	980,000,000
Collateral Pledged	2,562,000,000	1,455,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,450 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount	1,450,000,000
Outstanding	250,000,000	545,000,000
Collateral Pledged	2,371,000,000	1,306,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	345,000,000	405,000,000
Collateral Pledged	751,000,000	655,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	250,000,000	305,000,000
Collateral Pledged	787,000,000	634,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	250,000,000	250,000,000
Collateral Pledged	760,000,000	677,000,000
MSR Facilities | Servicing | Notes payable to banks | $50 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	50,000,000
Outstanding	25,000,000	29,000,000
Collateral Pledged	72,000,000	67,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	250,000,000	0
Collateral Pledged	486,000,000	0
Advance Financing, Internally Allocated | Servicing | Loans payable | $300 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount	300,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $950 million MSR facility
Debt Instrument [Line Items]
Capacity Amount	950,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $1,450 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount	1,450,000,000
Advance, Warehouse and MSR Facilities
Debt Instrument [Line Items]
Outstanding	4,939,000,000	4,318,000,000
Collateral Pledged	11,604,000,000	8,781,000,000
Unamortized debt issuance costs	(14,000,000)	(16,000,000)
Advance, warehouse and MSR facilities, net	$ 4,925,000,000	$ 4,302,000,000