Segment Information - Financial Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenues:
Service related, net	$ 588	$ (53)
Net gain on mortgage loans held for sale	679	331
Total revenues	1,267	278
Total expenses	469	444
Other income (expenses)
Interest income	89	118
Interest expense	(159)	(192)
Other income, net	0	1
Total other expenses, net	(70)	(73)
Income (loss) before income tax expense (benefit)	728	(239)
Depreciation and amortization for property and equipment and intangible assets	16	19
Total assets	24,713	17,613	$ 24,165
Operating Segments | Servicing
Revenues:
Service related, net	449	(180)
Net gain on mortgage loans held for sale	127	34
Total revenues	576	(146)
Total expenses	125	149
Other income (expenses)
Interest income	66	83
Interest expense	(104)	(113)
Other income, net		0
Total other expenses, net	(38)	(30)
Income (loss) before income tax expense (benefit)	413	(325)
Depreciation and amortization for property and equipment and intangible assets	5	3
Total assets	16,696	10,619
Operating Segments | Originations
Revenues:
Service related, net	43	20
Net gain on mortgage loans held for sale	552	297
Total revenues	595	317
Total expenses	231	166
Other income (expenses)
Interest income	23	34
Interest expense	(25)	(27)
Other income, net		0
Total other expenses, net	(2)	7
Income (loss) before income tax expense (benefit)	362	158
Depreciation and amortization for property and equipment and intangible assets	4	3
Total assets	5,559	4,459
Operating Segments | Xome
Revenues:
Service related, net	96	106
Net gain on mortgage loans held for sale	0	0
Total revenues	96	106
Total expenses	87	96
Other income (expenses)
Interest income	0	0
Interest expense	0	0
Other income, net		1
Total other expenses, net	0	1
Income (loss) before income tax expense (benefit)	9	11
Depreciation and amortization for property and equipment and intangible assets	3	3
Total assets	120	135
Corporate/Other
Revenues:
Service related, net	0	1
Net gain on mortgage loans held for sale	0	0
Total revenues	0	1
Total expenses	26	33
Other income (expenses)
Interest income	0	1
Interest expense	(30)	(52)
Other income, net		0
Total other expenses, net	(30)	(51)
Income (loss) before income tax expense (benefit)	(56)	(83)
Depreciation and amortization for property and equipment and intangible assets	4	10
Total assets	$ 2,338	$ 2,400