Indebtedness - Advance and Warehouse Facilities Summary (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Advance and warehouse facilities, net	$ 3,407,000,000	$ 4,997,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount	350,000,000
Debt outstanding, gross	156,000,000	160,000,000
Collateral Pledged	186,000,000	197,000,000
Advance Facilities | Servicing | Loans payable | $350 advance facility
Debt Instrument [Line Items]
Capacity Amount	350,000,000
Debt outstanding, gross	145,000,000	162,000,000
Collateral Pledged	172,000,000	190,000,000
Advance Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Debt outstanding, gross	523,000,000	614,000,000
Collateral Pledged	671,000,000	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	49,000,000	58,000,000
Collateral Pledged	70,000,000	89,000,000
Warehouse Facilities | Originations | Notes payable to banks
Debt Instrument [Line Items]
Debt outstanding, gross	1,939,000,000	4,125,000,000
Collateral Pledged	2,111,000,000	4,327,000,000
Warehouse Facilities | Originations | Notes payable to banks | $4,000 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	4,000,000,000
Debt outstanding, gross	661,000,000	1,224,000,000
Collateral Pledged	771,000,000	1,341,000,000
Warehouse Facilities | Originations | Notes payable to banks | $2,500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	2,500,000,000
Debt outstanding, gross	532,000,000	991,000,000
Collateral Pledged	550,000,000	1,024,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1,500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,500,000,000
Debt outstanding, gross	180,000,000	356,000,000
Collateral Pledged	180,000,000	345,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Debt outstanding, gross	241,000,000	256,000,000
Collateral Pledged	253,000,000	270,000,000
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 | $600 warehouse facility(2)
Debt Instrument [Line Items]
Capacity Amount	600,000,000
Debt outstanding, gross	91,000,000	409,000,000
Collateral Pledged	101,000,000	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	9,000,000	188,000,000
Collateral Pledged	10,000,000	194,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Debt outstanding, gross	117,000,000	419,000,000
Collateral Pledged	120,000,000	430,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Debt outstanding, gross	57,000,000	39,000,000
Collateral Pledged	68,000,000	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	31,000,000	38,000,000
Collateral Pledged	32,000,000	39,000,000
Warehouse Facilities | Originations | Notes payable to banks | $325 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	325,000,000
Debt outstanding, gross	1,000,000	67,000,000
Collateral Pledged	1,000,000	67,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 warehouse facility(3)
Debt Instrument [Line Items]
Capacity Amount	250,000,000	600
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	19,000,000	46,000,000
Collateral Pledged	25,000,000	58,000,000
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	950,000,000	270,000,000
Collateral Pledged	5,054,000,000	2,814,000,000
MSR Facilities | Servicing | Notes payable to banks | $800 warehouse facility(1)(5)
Debt Instrument [Line Items]
Capacity Amount	800,000,000	260,000,000
Debt outstanding, gross	260,000,000	260,000,000
Collateral Pledged	2,008,000,000	1,107,000,000
MSR Facilities | Servicing | Notes payable to banks | $600 warehouse facility(6)
Debt Instrument [Line Items]
Capacity Amount	600,000,000	400,000,000
Debt outstanding, gross	400,000,000	0
Collateral Pledged	883,000,000	838,000,000
MSR Facilities | Servicing | Notes payable to banks | $400 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	400,000,000
Debt outstanding, gross	200,000,000	0
Collateral Pledged	710,000,000	0
MSR Facilities | Servicing | Notes payable to banks | $400 warehouse facility(2)
Debt Instrument [Line Items]
Capacity Amount	400,000,000
Debt outstanding, gross	65,000,000	0
Collateral Pledged	1,376,000,000	745,000,000
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	77,000,000	124,000,000
MSR Facilities | Servicing | Notes payable to banks | $1,200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,200,000,000	1,200,000,000
Advance Financing, Internally Allocated | Servicing | Loans payable | $400 advance facility(1)
Debt Instrument [Line Items]
Capacity Amount	400,000,000	940,000,000
Debt outstanding, gross	173,000,000	234,000,000
Collateral Pledged	243,000,000	318,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $800 warehouse facility(1)(5)
Debt Instrument [Line Items]
Capacity Amount	800,000,000	260,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $400 warehouse facility(2)
Debt Instrument [Line Items]
Capacity Amount	400,000,000
Advance, Warehouse and MSR Facilities
Debt Instrument [Line Items]
Debt outstanding, gross	3,412,000,000	5,009,000,000
Collateral Pledged	7,836,000,000	7,935,000,000
Unamortized debt issuance costs	(5,000,000)	(12,000,000)
Advance and warehouse facilities, net	$ 3,407,000,000	$ 4,997,000,000