Indebtedness - Advance and Warehouse Facilities Summary (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Advance, warehouse and MSR facilities, net	$ 3,512,000,000	$ 2,885,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount	350,000,000
Outstanding	134,000,000	150,000,000
Collateral Pledged	169,000,000	189,000,000
Advance Facilities | Servicing | Loans payable | $300 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount	300,000,000
Outstanding	259,000,000	308,000,000
Collateral Pledged	354,000,000	410,000,000
Advance Facilities | Servicing | Loans payable | $250 advance facility
Debt Instrument [Line Items]
Capacity Amount	250,000,000
Outstanding	183,000,000	171,000,000
Collateral Pledged	210,000,000	209,000,000
Advance Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding	610,000,000	669,000,000
Collateral Pledged	798,000,000	853,000,000
Advance Facilities | Servicing | Notes payable to banks | $75 advance facility
Debt Instrument [Line Items]
Capacity Amount	75,000,000
Outstanding	34,000,000	40,000,000
Collateral Pledged	65,000,000	45,000,000
Warehouse Facilities | Originations
Debt Instrument [Line Items]
Outstanding	1,107,000,000	817,000,000
Warehouse Facilities | Originations | Notes payable to banks
Debt Instrument [Line Items]
Collateral Pledged	1,197,000,000	910,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1500 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	1,500,000,000
Outstanding	251,000,000	206,000,000
Collateral Pledged	252,000,000	272,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Outstanding	186,000,000	135,000,000
Collateral Pledged	239,000,000	133,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Outstanding	155,000,000	202,000,000
Collateral Pledged	161,000,000	209,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 Warehouse Facility(2)
Debt Instrument [Line Items]
Capacity Amount	250,000,000
Outstanding	47,000,000	14,000,000
Collateral Pledged	52,000,000	17,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	78,000,000	76,000,000
Collateral Pledged	84,000,000	80,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	101,000,000	31,000,000
Collateral Pledged	103,000,000	32,000,000
Warehouse Facilities | Originations | Notes payable to banks | $300 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	300,000,000
Outstanding	183,000,000	115,000,000
Collateral Pledged	188,000,000	117,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	200,000,000
Outstanding	59,000,000	18,000,000
Collateral Pledged	61,000,000	21,000,000
Warehouse Facilities | Originations | Notes payable to banks | $100 Warehouse Facility
Debt Instrument [Line Items]
Capacity Amount	100,000,000
Outstanding	29,000,000	19,000,000
Collateral Pledged	39,000,000	28,000,000
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 | $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	1,809,000,000	1,410,000,000
Collateral Pledged	6,147,000,000	5,499,000,000
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	260,000,000
Collateral Pledged	2,185,000,000	2,284,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,000 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,000,000,000
Outstanding	550,000,000	380,000,000
Collateral Pledged	1,235,000,000	927,000,000
MSR Facilities | Servicing | Notes payable to banks | $750 warehouse facility(2)
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Outstanding	320,000,000	380,000,000
Collateral Pledged	1,141,000,000	1,482,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	265,000,000	365,000,000
Collateral Pledged	713,000,000	732,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	199,000,000	0
Collateral Pledged	383,000,000	0
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	200,000,000	0
Collateral Pledged	424,000,000	0
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	66,000,000	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
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Advance, Warehouse and MSR Facilities
Debt Instrument [Line Items]
Outstanding	3,526,000,000	2,896,000,000
Collateral Pledged	8,142,000,000	7,262,000,000
Unamortized debt issuance costs	(14,000,000)	(11,000,000)
Advance, warehouse and MSR facilities, net	$ 3,512,000,000	$ 2,885,000,000