Indebtedness - Advance and Warehouse Facilities Summary (Details) - USD ($)	Mar. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Advance, warehouse and MSR facilities, net	$ 6,313,000,000	$ 6,495,000,000
Advance Facilities | Servicing | Loans payable | $350 Advance Facility Due October 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	350,000,000
Outstanding	108,000,000	119,000,000
Collateral Pledged	136,000,000	151,000,000
Advance Facilities | Servicing | Loans payable | $500 Advance Facility Due August 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	318,000,000	423,000,000
Collateral Pledged	358,000,000	475,000,000
Advance Facilities | Servicing | Loans payable | $50 Advance facility due July 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	50,000,000
Outstanding	22,000,000	22,000,000
Collateral Pledged	26,000,000	40,000,000
Advance Facilities | Servicing | Loans payable | $500 Advance Facility Due July 2026
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	257,000,000	285,000,000
Collateral Pledged	366,000,000	394,000,000
Advance Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding	705,000,000	849,000,000
Collateral Pledged	886,000,000	1,060,000,000
Advance Facilities | Servicing | Notes payable to banks | $50 Advance facility due July 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	50,000,000
Warehouse Facilities | Originations | Notes payable to banks
Debt Instrument [Line Items]
Outstanding	2,324,000,000	2,016,000,000
Collateral Pledged	2,505,000,000	2,168,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1500 Warehouse Facility Due June 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	1,500,000,000
Outstanding	90,000,000	68,000,000
Collateral Pledged	90,000,000	71,000,000
Warehouse Facilities | Originations | Notes payable to banks | $750 Warehouse Facility due March 2027 [Member]
Debt Instrument [Line Items]
Capacity Amount	750,000,000
Outstanding	195,000,000	112,000,000
Collateral Pledged	230,000,000	140,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1000 Warehouse Facility Due October 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	1,000,000,000	750,000,000
Outstanding	388,000,000	489,000,000
Collateral Pledged	417,000,000	530,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 Million WH Facility Due June 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	56,000,000	90,000,000
Collateral Pledged	72,000,000	99,000,000
Warehouse Facilities | Originations | Notes payable to banks | $600 Million Warehouse Facility Due August 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	600,000,000
Outstanding	404,000,000	368,000,000
Collateral Pledged	413,000,000	381,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1200 Warehouse Facility Due September 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	1,200,000,000
Outstanding	283,000,000	131,000,000
Collateral Pledged	323,000,000	148,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 Million Warehouse Facility Due December 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	200,000,000
Outstanding	159,000,000	112,000,000
Collateral Pledged	181,000,000	123,000,000
Warehouse Facilities | Originations | Notes payable to banks | $200 Warehouse Facility due April 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	200,000,000
Outstanding	0	0
Collateral Pledged	0	0
Warehouse Facilities | Originations | Notes payable to banks | $100 million WH facility due April 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	100,000,000
Outstanding	36,000,000	56,000,000
Collateral Pledged	41,000,000	62,000,000
Warehouse Facilities | Originations | Notes payable to banks | $100 million warehouse facility due April 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	100,000,000
Outstanding	0	0
Collateral Pledged	0	0
Warehouse Facilities | Originations | Notes payable to banks | $200 Warehouse Facility due July 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	200,000,000
Outstanding	145,000,000	105,000,000
Collateral Pledged	145,000,000	105,000,000
Warehouse Facilities | Originations | Notes payable to banks | $1 Warehouse Facility due December 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	1,000,000
Outstanding	0	0
Collateral Pledged	0	0
Warehouse Facilities | Originations | Notes payable to banks | $1,200 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	1,200,000,000
Warehouse Facilities | Originations | Notes payable to banks | $500 Million WH Facility Due November 2025
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	413,000,000	247,000,000
Collateral Pledged	427,000,000	256,000,000
Warehouse Facilities | Originations | Notes payable to banks | $250 Million WH Facility Due November 2025
Debt Instrument [Line Items]
Capacity Amount	250,000,000
Outstanding	155,000,000	238,000,000
Collateral Pledged	166,000,000	253,000,000
MSR Facilities | Servicing | Notes payable to banks
Debt Instrument [Line Items]
Outstanding	3,300,000,000	3,650,000,000
Collateral Pledged	10,452,000,000	10,788,000,000
MSR Facilities | Servicing | Notes payable to banks | $1750 warehouse facility
Debt Instrument [Line Items]
Capacity Amount	2,000,000,000
MSR Facilities | Servicing | Notes payable to banks | $950 million MSR facility
Debt Instrument [Line Items]
Capacity Amount	950,000,000
Outstanding	345,000,000	550,000,000
Collateral Pledged	1,414,000,000	1,711,000,000
MSR Facilities | Servicing | Notes payable to banks | $1750 million MSR facility due April 2026Member [Member]
Debt Instrument [Line Items]
Capacity Amount	1,750,000,000
Outstanding	900,000,000	950,000,000
Collateral Pledged	2,753,000,000	2,669,000,000
MSR Facilities | Servicing | Notes payable to banks | $950 MSR WH Facility Due July 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	950,000,000	750,000,000
Outstanding	550,000,000	670,000,000
Collateral Pledged	1,017,000,000	1,066,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 MSR Facility Due April 2027 [Member]
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	250,000,000	250,000,000
Collateral Pledged	752,000,000	781,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 MSR Facility Due June 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	150,000,000	150,000,000
Collateral Pledged	736,000,000	726,000,000
MSR Facilities | Servicing | Notes payable to banks | $50 Warehouse Facility Due November 2025 [Member]
Debt Instrument [Line Items]
Capacity Amount	50,000,000
Outstanding	25,000,000	25,000,000
Collateral Pledged	85,000,000	80,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 MSR WH Facility Due June 2026 [Member]
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	250,000,000	250,000,000
Collateral Pledged	496,000,000	519,000,000
MSR Facilities | Servicing | Notes payable to banks | $1500 million MSR facility due July 2026
Debt Instrument [Line Items]
Capacity Amount	1,500,000,000
Outstanding	475,000,000	475,000,000
Collateral Pledged	2,583,000,000	2,607,000,000
MSR Facilities | Servicing | Notes payable to banks | $500 MSR WH Mizuho Facility Due July 2026
Debt Instrument [Line Items]
Capacity Amount	500,000,000
Outstanding	355,000,000	330,000,000
Collateral Pledged	616,000,000	629,000,000
Advance Financing, Internally Allocated | Servicing | Loans payable | $500 Advance Facility Due July 2026
Debt Instrument [Line Items]
Capacity Amount	500,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $950 million MSR facility
Debt Instrument [Line Items]
Capacity Amount	950,000,000
MSR Financing, Internally Allocated | Servicing | Notes payable to banks | $1500 million MSR facility due July 2026
Debt Instrument [Line Items]
Capacity Amount	1,500,000,000
Advance, Warehouse and MSR Facilities
Debt Instrument [Line Items]
Outstanding	6,329,000,000	6,515,000,000
Collateral Pledged	13,843,000,000	14,016,000,000
Unamortized debt issuance costs	(16,000,000)	(20,000,000)
Advance, warehouse and MSR facilities, net	$ 6,313,000,000	$ 6,495,000,000