Segment Information - Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Revenues:
Service related, net	$ 432	$ 395	$ 1,095	$ 1,610
Net gain on mortgage loans held for sale	142	115	295	551
Total revenues	574	510	1,390	2,161
Total expenses	301	316	840	982
Other income (expenses)
Interest income	167	83	369	169
Interest expense	(146)	(104)	(378)	(321)
Other income, net	58	(20)	44	197
Total other income (expenses), net	79	(41)	35	45
Income before income tax expense	352	153	585	1,224
Depreciation and amortization for property and equipment and intangible assets	10	9	28	29
Total assets	13,427	12,815	13,427	12,815	$ 12,776
2023 Trust Collapse
Other income (expenses)
Payments to Acquire Retained Interest in Securitized Receivables	82
Proceeds from Sale, Loan, Held-for-Sale	67
UPB	207		207
Operating Segments | Servicing
Revenues:
Service related, net	392	353	988	1,468
Net gain on mortgage loans held for sale	72	(21)	75	(25)
Total revenues	464	332	1,063	1,443
Total expenses	172	147	484	412
Other income (expenses)
Interest income	157	71	343	125
Interest expense	(88)	(53)	(224)	(168)
Other income, net	0	0	0	0
Total other income (expenses), net	69	18	119	(43)
Income before income tax expense	361	203	698	988
Depreciation and amortization for property and equipment and intangible assets	4	6	9	16
Total assets	10,916	9,703	10,916	9,703
Operating Segments | Originations
Revenues:
Service related, net	18	20	45	86
Net gain on mortgage loans held for sale	70	136	220	576
Total revenues	88	156	265	662
Total expenses	58	111	173	410
Other income (expenses)
Interest income	10	12	26	44
Interest expense	(11)	(11)	(28)	(33)
Other income, net	0	0	0	0
Total other income (expenses), net	(1)	1	(2)	11
Income before income tax expense	29	46	90	263
Depreciation and amortization for property and equipment and intangible assets	2	5	6	14
Total assets	868	1,252	868	1,252
Corporate/Other
Revenues:
Service related, net	22	22	62	56
Net gain on mortgage loans held for sale	0	0	0	0
Total revenues	22	22	62	56
Total expenses	71	58	183	160
Other income (expenses)
Interest income	0	0	0	0
Interest expense	(47)	(40)	(126)	(120)
Other income, net	58	(20)	44	197
Total other income (expenses), net	11	(60)	(82)	77
Income before income tax expense	(38)	(96)	(203)	(27)
Depreciation and amortization for property and equipment and intangible assets	4	(2)	13	(1)
Total assets	$ 1,643	$ 1,860	$ 1,643	$ 1,860