Segment Information - Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2023
Revenues:
Service related, net	$ 1,440	$ 1,865	$ 1,067
Net gain on mortgage loans held for sale	354	599	2,251
Total revenues	1,794	2,464	3,318
Total expenses	1,172	1,274	1,662
Other Nonoperating Income (Expense) [Abstract]
Interest income	528	261	231
Interest expense	(537)	(424)	(478)
Other income (expenses), net	41	187	528
Total other income (expenses), net	32	24	281
Income from continuing operations before income tax expense	654	1,214	1,937
Depreciation and amortization for property and equipment and intangible assets from continuing operations	38	37	57
Total assets	14,196	12,776	14,204
2023 Trust Collapse
Other Nonoperating Income (Expense) [Abstract]
Payments to Acquire Retained Interest in Securitized Receivables	82
Principal amount outstanding on mortgage servicing rights				$ 207
Proceeds from Sale, Loan, Held-for-Sale	67
Operating Segments | Servicing
Revenues:
Service related, net	1,295	1,691	705
Net gain on mortgage loans held for sale	84	(33)	568
Total revenues	1,379	1,658	1,273
Total expenses	664	559	502
Other Nonoperating Income (Expense) [Abstract]
Interest income	491	208	129
Interest expense	(324)	(221)	(262)
Other income (expenses), net	0	0	0
Total other income (expenses), net	167	(13)	(133)
Income from continuing operations before income tax expense	882	1,086	638
Depreciation and amortization for property and equipment and intangible assets from continuing operations	12	18	32
Total assets	11,740	10,152	8,733
Operating Segments | Originations
Revenues:
Service related, net	61	98	176
Net gain on mortgage loans held for sale	271	632	1,683
Total revenues	332	730	1,859
Total expenses	232	491	849
Other Nonoperating Income (Expense) [Abstract]
Interest income	36	53	102
Interest expense	(37)	(43)	(88)
Other income (expenses), net	0	0	0
Total other income (expenses), net	(1)	10	14
Income from continuing operations before income tax expense	99	249	1,024
Depreciation and amortization for property and equipment and intangible assets from continuing operations	8	16	24
Total assets	782	749	3,143
Corporate/ Other
Revenues:
Service related, net	84	76	186
Net gain on mortgage loans held for sale	(1)	0	0
Total revenues	83	76	186
Total expenses	276	224	311
Other Nonoperating Income (Expense) [Abstract]
Interest income	1	0	0
Interest expense	(176)	(160)	(128)
Other income (expenses), net	41	187	528
Total other income (expenses), net	(134)	27	400
Income from continuing operations before income tax expense	(327)	(121)	275
Depreciation and amortization for property and equipment and intangible assets from continuing operations	18	3	1
Total assets	$ 1,674	$ 1,875	$ 2,328