Indebtedness - Advance and Warehouse Facilities Summary (Details) - USD ($)	Apr. 01, 2024	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Advance, warehouse and MSR facilities, net		$ 4,087,000,000	$ 4,302,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount		350,000,000
Outstanding		122,000,000	132,000,000
Collateral Pledged		158,000,000	169,000,000
Advance Facilities | Servicing | Loans payable | $250 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount		250,000,000
Outstanding		230,000,000	273,000,000
Collateral Pledged		313,000,000	364,000,000
Advance Facilities | Servicing | Loans payable | $300 advance facility
Debt Instrument [Line Items]
Capacity Amount		300,000,000
Outstanding		271,000,000	250,000,000
Collateral Pledged		305,000,000	326,000,000
Advance Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding		650,000,000	682,000,000
Collateral Pledged		825,000,000	908,000,000
Advance Facilities | Servicing | Notes payable to banks | $50 advance facility(2)
Debt Instrument [Line Items]
Capacity Amount		50,000,000
Outstanding		27,000,000	27,000,000
Collateral Pledged		49,000,000	49,000,000
Warehouse Facilities | Originations
Debt Instrument [Line Items]
Outstanding		958,000,000	822,000,000
Warehouse Facilities | Originations | Notes payable to banks
Debt Instrument [Line Items]
Collateral Pledged		1,065,000,000	915,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
Outstanding		141,000,000	107,000,000
Collateral Pledged		141,000,000	104,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		750,000,000
Outstanding		138,000,000	137,000,000
Collateral Pledged		175,000,000	176,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		750,000,000
Outstanding		172,000,000	155,000,000
Collateral Pledged		190,000,000	166,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Outstanding		54,000,000	72,000,000
Collateral Pledged		58,000,000	78,000,000
Warehouse Facilities | Originations | Notes payable to banks | $350 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		350,000,000
Outstanding		138,000,000	73,000,000
Collateral Pledged		141,000,000	75,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 warehouse facility(3)
Debt Instrument [Line Items]
Capacity Amount		250,000,000
Outstanding		177,000,000	158,000,000
Collateral Pledged		203,000,000	177,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		200,000,000
Outstanding		10,000,000	82,000,000
Collateral Pledged		10,000,000	84,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		200,000,000
Outstanding		11,000,000	12,000,000
Collateral Pledged		21,000,000	21,000,000
Warehouse Facilities | Originations | Notes payable to banks | $100 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		100,000,000
Outstanding		52,000,000	25,000,000
Collateral Pledged		61,000,000	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 (2)
Debt Instrument [Line Items]
Capacity Amount		100,000,000
Outstanding		65,000,000	1,000,000
Collateral Pledged		65,000,000	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 | $1,000 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,200,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1500 million MSR facility due April 2026Member | Subsequent Event
Debt Instrument [Line Items]
Capacity Amount	$ 1,750,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1000 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		1,000,000,000
MSR Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding		2,495,000,000	2,814,000,000
Collateral Pledged		8,871,000,000	6,958,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,500 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
Outstanding		250,000,000	300,000,000
Collateral Pledged		2,334,000,000	2,164,000,000
MSR Facilities | Servicing | Notes payable to banks | $950 warehouse facility(3)
Debt Instrument [Line Items]
Capacity Amount		950,000,000
Outstanding		585,000,000	545,000,000
Collateral Pledged		1,633,000,000	1,306,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Outstanding		335,000,000	405,000,000
Collateral Pledged		724,000,000	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		788,000,000	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		753,000,000	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		68,000,000	67,000,000
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 | $1500 million MSR facility due April 2026Member
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
Outstanding		800,000,000	980,000,000
Collateral Pledged		2,571,000,000	1,455,000,000
Advance Financing, Internally Allocated | Servicing | Loans payable | $250 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount		250,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $1,500 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $950 warehouse facility(3)
Debt Instrument [Line Items]
Capacity Amount		950,000,000
Advance, Warehouse and MSR Facilities
Debt Instrument [Line Items]
Outstanding		4,103,000,000	4,318,000,000
Collateral Pledged		10,761,000,000	8,781,000,000
Unamortized debt issuance costs		(16,000,000)	(16,000,000)
Advance, warehouse and MSR facilities, net		$ 4,087,000,000	$ 4,302,000,000