Indebtedness - Advance and Warehouse Facilities Summary (Details) - USD ($)	Oct. 01, 2022	Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Advance and warehouse facilities, net		$ 3,070,000,000	$ 4,997,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount		350,000,000
Debt outstanding, gross		150,000,000	160,000,000
Collateral Pledged		182,000,000	197,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount		350,000,000
Debt outstanding, gross		130,000,000	162,000,000
Collateral Pledged		154,000,000	190,000,000
Advance Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Debt outstanding, gross		532,000,000	614,000,000
Collateral Pledged		674,000,000	794,000,000
Advance Facilities | Servicing | Notes payable to banks | $75 advance facility
Debt Instrument [Line Items]
Capacity Amount		75,000,000
Debt outstanding, gross		46,000,000	58,000,000
Collateral Pledged		48,000,000	89,000,000
Warehouse Facilities | Originations | Notes payable to banks
Debt Instrument [Line Items]
Debt outstanding, gross		1,504,000,000	4,125,000,000
Collateral Pledged		1,676,000,000	4,327,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
Debt outstanding, gross		427,000,000	1,224,000,000
Collateral Pledged		531,000,000	1,341,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,500,000,000
Debt outstanding, gross		328,000,000	356,000,000
Collateral Pledged		341,000,000	345,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,000 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,000,000,000
Debt outstanding, gross		235,000,000	991,000,000
Collateral Pledged		244,000,000	1,024,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 warehouse facility(2)
Debt Instrument [Line Items]
Capacity Amount		750,000,000
Debt outstanding, gross		258,000,000	256,000,000
Collateral Pledged		274,000,000	270,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 warehouse facility(3)
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Debt outstanding, gross		144,000,000	409,000,000
Collateral Pledged		157,000,000	425,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Debt outstanding, gross		24,000,000	39,000,000
Collateral Pledged		30,000,000	39,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Debt outstanding, gross		12,000,000	38,000,000
Collateral Pledged		13,000,000	39,000,000
Warehouse Facilities | Originations | Notes payable to banks | $450 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		450,000,000
Debt outstanding, gross		0	87,000,000
Collateral Pledged		0	89,000,000
Warehouse Facilities | Originations | Notes payable to banks | $300 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		300,000,000
Debt outstanding, gross		55,000,000	419,000,000
Collateral Pledged		58,000,000	430,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		250,000,000
Debt outstanding, gross		0	5,000,000
Collateral Pledged		0	6,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		200,000,000
Debt outstanding, gross		5,000,000	188,000,000
Collateral Pledged		8,000,000	194,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		200,000,000
Debt outstanding, gross		13,000,000	46,000,000
Collateral Pledged		17,000,000	58,000,000
Warehouse Facilities | Originations | Notes payable to banks | $125 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		125,000,000
Debt outstanding, gross		3,000,000	67,000,000
Collateral Pledged		3,000,000	67,000,000
Warehouse Facilities | Originations | Notes payable to banks | $30 warehouse facility(4)
Debt Instrument [Line Items]
Capacity Amount		0
Debt outstanding, gross		0	0
Collateral Pledged		0	0
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]
Debt outstanding, gross		1,040,000,000	270,000,000
Collateral Pledged		5,154,000,000	2,814,000,000
MSR Facilities | Servicing | Notes payable to banks | $900 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount		900,000,000
Debt outstanding, gross		260,000,000	260,000,000
Collateral Pledged		2,028,000,000	1,107,000,000
MSR Facilities | Servicing | Notes payable to banks | $600 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		600,000,000
Debt outstanding, gross		325,000,000	0
Collateral Pledged		911,000,000	838,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 warehouse facility(3)
Debt Instrument [Line Items]
Capacity Amount		500,000,000
Debt outstanding, gross		180,000,000	0
Collateral Pledged		1,435,000,000	745,000,000
MSR Facilities | Servicing | Notes payable to banks | $400 warehouse facility(5)
Debt Instrument [Line Items]
Capacity Amount		400,000,000
Debt outstanding, gross		250,000,000	0
Collateral Pledged		705,000,000	0
MSR Facilities | Servicing | Notes payable to banks | $50 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		50,000,000
Debt outstanding, gross		25,000,000	10,000,000
Collateral Pledged		75,000,000	124,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount		1,200,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,200 warehouse facility | Subsequent Event
Debt Instrument [Line Items]
Capacity Amount	$ 1,400,000,000
Advance Financing, Internally Allocated | Servicing | Loans payable | $300 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount		300,000,000
Debt outstanding, gross		206,000,000	234,000,000
Collateral Pledged		290,000,000	318,000,000
Advance Financing, Internally Allocated | Servicing | Loans payable | $300 advance facility(1) | Subsequent Event
Debt Instrument [Line Items]
Capacity Amount	300,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $900 warehouse facility(1)
Debt Instrument [Line Items]
Capacity Amount		900,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $900 warehouse facility(1) | Subsequent Event
Debt Instrument [Line Items]
Capacity Amount	1,100,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $500 warehouse facility(3)
Debt Instrument [Line Items]
Capacity Amount		500,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $400 warehouse facility(5) | Subsequent Event
Debt Instrument [Line Items]
Capacity Amount	$ 500,000,000
Advance, Warehouse and MSR Facilities
Debt Instrument [Line Items]
Debt outstanding, gross		3,076,000,000	5,009,000,000
Collateral Pledged		7,504,000,000	7,935,000,000
Unamortized debt issuance costs		(6,000,000)	(12,000,000)
Advance and warehouse facilities, net		$ 3,070,000,000	$ 4,997,000,000