Indebtedness - Advance and Warehouse Facilities Summary (Details) - USD ($)	Apr. 01, 2023	Mar. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Advance and warehouse facilities, net		$ 2,934,000,000	$ 2,885,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount		350,000,000
Outstanding		140,000,000	150,000,000
Collateral Pledged		179,000,000	189,000,000
Advance Facilities | Servicing | Loans payable | $300 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount		300,000,000
Outstanding		298,000,000	308,000,000
Collateral Pledged		406,000,000	410,000,000
Advance Facilities | Servicing | Loans payable | $250 advance facility
Debt Instrument [Line Items]
Capacity Amount		250,000,000
Outstanding		161,000,000	171,000,000
Collateral Pledged		192,000,000	209,000,000
Advance Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding		642,000,000	669,000,000
Collateral Pledged		842,000,000	853,000,000
Advance Facilities | Servicing | Notes payable to banks | $75 advance facility
Debt Instrument [Line Items]
Capacity Amount		75,000,000
Outstanding		43,000,000	40,000,000
Collateral Pledged		65,000,000	45,000,000
Warehouse Facilities | Originations | Notes payable to banks
Debt Instrument [Line Items]
Outstanding		865,000,000	817,000,000
Collateral Pledged		948,000,000	910,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,500 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
Outstanding		189,000,000	206,000,000
Collateral Pledged		247,000,000	272,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,500 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
Outstanding		145,000,000	135,000,000
Collateral Pledged		144,000,000	133,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		750,000,000
Outstanding		135,000,000	202,000,000
Collateral Pledged		140,000,000	209,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 Warehouse Facility(2)
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Outstanding		9,000,000	14,000,000
Collateral Pledged		11,000,000	17,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Outstanding		64,000,000	76,000,000
Collateral Pledged		67,000,000	80,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Outstanding		76,000,000	31,000,000
Collateral Pledged		78,000,000	32,000,000
Warehouse Facilities | Originations | Notes payable to banks | $450 Warehouse Facility(3)
Debt Instrument [Line Items]
Capacity Amount		450,000,000
Outstanding		0	0
Collateral Pledged		0	0
Warehouse Facilities | Originations | Notes payable to banks | $450 Warehouse Facility(3) | Subsequent Event
Debt Instrument [Line Items]
Capacity Amount	$ 100,000,000
Warehouse Facilities | Originations | Notes payable to banks | $300 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		300,000,000
Outstanding		161,000,000	115,000,000
Collateral Pledged		165,000,000	117,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 Warehouse Facility(4)
Debt Instrument [Line Items]
Capacity Amount		250,000,000
Outstanding		0	0
Collateral Pledged		0	0
Warehouse Facilities | Originations | Notes payable to banks | $200 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		200,000,000
Outstanding		18,000,000	19,000,000
Collateral Pledged		27,000,000	28,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		200,000,000
Outstanding		50,000,000	18,000,000
Collateral Pledged		51,000,000	21,000,000
Warehouse Facilities | Originations | Notes payable to banks | $75 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount		75,000,000
Outstanding		18,000,000	1,000,000
Collateral Pledged		18,000,000	1,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,000 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,000,000,000
MSR Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding		1,440,000,000	1,410,000,000
Collateral Pledged		5,137,000,000	5,499,000,000
MSR Facilities | Servicing | Notes payable to banks | Subsequent Event
Debt Instrument [Line Items]
Capacity Amount	$ 1,150,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,450 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount		1,450,000,000
Outstanding		300,000,000	260,000,000
Collateral Pledged		2,162,000,000	2,284,000,000
MSR Facilities | Servicing | Notes payable to banks | $600 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		600,000,000
Outstanding		400,000,000	380,000,000
Collateral Pledged		977,000,000	927,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility(2)
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Outstanding		390,000,000	380,000,000
Collateral Pledged		1,153,000,000	1,482,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Outstanding		325,000,000	365,000,000
Collateral Pledged		774,000,000	732,000,000
MSR Facilities | Servicing | Notes payable to banks | $50 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		50,000,000
Outstanding		25,000,000	25,000,000
Collateral Pledged		71,000,000	74,000,000
MSR Facilities | Servicing | Notes payable to banks | $1750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,750,000,000
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 | $1,450 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount		1,450,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $500 warehouse facility(2)
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Advance, Warehouse and MSR Facilities
Debt Instrument [Line Items]
Outstanding		2,947,000,000	2,896,000,000
Collateral Pledged		6,927,000,000	7,262,000,000
Unamortized debt issuance costs		(13,000,000)	(11,000,000)
Advance and warehouse facilities, net		$ 2,934,000,000	$ 2,885,000,000