Guarantor Financial Statement Information - Consolidating Statements of Operations (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended							5 Months Ended	7 Months Ended	12 Months Ended
	Jul. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Condensed Financial Statements
Service related, net	$ 120	$ 259	$ 430	$ 258	$ 137	$ 84	$ 159	$ 317	$ 464	$ 418	$ 901	$ 909	$ 1,043
Net gain on mortgage loans held for sale	44	83	310	360	262	166	93	127	124	176	295	1,098	607
Total revenues	164	342	740	618	399	250	252	444	588	594	1,196	2,007	1,650
Expenses:
Salaries, wages benefits										337	426	957	742
General and administrative										370	519	894	733
Total expenses	242	275	438	478	492	443	432	339	364	707	945	1,851	1,475
Other income (expenses), net:
Interest income										256	333	605	597
Interest expense										(293)	(388)	(779)	(731)
Other income, net										13	6	15	3
Gain (loss) from subsidiaries										0	0	0	0
Total other income (expenses), net	(5)	(26)	(62)	(33)	(24)	(40)	2	(26)	(18)	(24)	(49)	(159)	(131)
(Loss) income before income tax expense	(83)	41	240	107	(117)	(233)	(178)	79	206	(137)	202	(3)	44
Less: Income tax (benefit) expense	(19)	(979)	(221)	24	(29)	(47)	(42)	21	46	(1,021)	48	(273)	13
Net income (loss)	(64)	1,020	461	83	(88)	(186)	(136)	58	160	884	154	270	31
Less: Net (loss) income attributable to non-controlling interests	0	0	(2)	(1)	(1)	0	0	0	0	0	0	(4)	1
Net income attributable to Successor/Predecessor	$ (64)	$ 1,020	$ 463	$ 84	$ (87)	$ (186)	$ (136)	$ 58	$ 160	884	154	274	30
Reportable legal entities | Mr. Cooper
Condensed Financial Statements
Service related, net										0	0	0	0
Net gain on mortgage loans held for sale										0	0	0	0
Total revenues										0	0	0	0
Expenses:
Salaries, wages benefits										1	0	0	0
General and administrative										0	27	0	0
Total expenses										1	27	0	0
Other income (expenses), net:
Interest income										0	0	0	0
Interest expense										(64)	0	(153)	0
Other income, net										1	0	0	0
Gain (loss) from subsidiaries										(44)	181	142	30
Total other income (expenses), net										(107)	181	(11)	30
(Loss) income before income tax expense										(108)	154	(11)	30
Less: Income tax (benefit) expense										(992)	0	(285)	0
Net income (loss)										884	154	274	30
Less: Net (loss) income attributable to non-controlling interests										0	0	0	0
Net income attributable to Successor/Predecessor										884	154	274	30
Reportable legal entities | Issuer
Condensed Financial Statements
Service related, net										233	732	451	717
Net gain on mortgage loans held for sale										175	295	1,087	606
Total revenues										408	1,027	1,538	1,323
Expenses:
Salaries, wages benefits										258	359	794	605
General and administrative										262	427	651	590
Total expenses										520	786	1,445	1,195
Other income (expenses), net:
Interest income										237	299	525	544
Interest expense										(211)	(364)	(566)	(675)
Other income, net										11	(3)	1	(6)
Gain (loss) from subsidiaries										2	56	98	53
Total other income (expenses), net										39	(12)	58	(84)
(Loss) income before income tax expense										(73)	229	151	44
Less: Income tax (benefit) expense										(29)	48	13	13
Net income (loss)										(44)	181	138	31
Less: Net (loss) income attributable to non-controlling interests										0	0	(4)	1
Net income attributable to Successor/Predecessor										(44)	181	142	30
Reportable legal entities | Guarantor (Subsidiaries of Issuer)
Condensed Financial Statements
Service related, net										9	16	22	28
Net gain on mortgage loans held for sale										0	0	0	0
Total revenues										9	16	22	28
Expenses:
Salaries, wages benefits										2	3	5	5
General and administrative										1	1	2	11
Total expenses										3	4	7	16
Other income (expenses), net:
Interest income										0	0	0	0
Interest expense										0	0	0	0
Other income, net										0	0	(15)	0
Gain (loss) from subsidiaries										0	0	0	0
Total other income (expenses), net										0	0	(15)	0
(Loss) income before income tax expense										6	12	0	12
Less: Income tax (benefit) expense										0	0	0	0
Net income (loss)										6	12	0	12
Less: Net (loss) income attributable to non-controlling interests										0	0	0	0
Net income attributable to Successor/Predecessor										6	12	0	12
Reportable legal entities | Non-Guarantor (Subsidiaries of Issuer)
Condensed Financial Statements
Service related, net										176	153	436	298
Net gain on mortgage loans held for sale										1	0	11	1
Total revenues										177	153	447	299
Expenses:
Salaries, wages benefits										76	64	158	132
General and administrative										107	64	241	132
Total expenses										183	128	399	264
Other income (expenses), net:
Interest income										19	34	80	53
Interest expense										(18)	(24)	(60)	(56)
Other income, net										1	9	29	9
Gain (loss) from subsidiaries										0	0	0	0
Total other income (expenses), net										2	19	49	6
(Loss) income before income tax expense										(4)	44	97	41
Less: Income tax (benefit) expense										0	0	(1)	0
Net income (loss)										(4)	44	98	41
Less: Net (loss) income attributable to non-controlling interests										0	0	0	0
Net income attributable to Successor/Predecessor										(4)	44	98	41
Eliminations
Condensed Financial Statements
Service related, net										0	0	0	0
Net gain on mortgage loans held for sale										0	0	0	0
Total revenues										0	0	0	0
Expenses:
Salaries, wages benefits										0	0	0	0
General and administrative										0	0	0	0
Total expenses										0	0	0	0
Other income (expenses), net:
Interest income										0	0	0	0
Interest expense										0	0	0	0
Other income, net										0	0	0	0
Gain (loss) from subsidiaries										42	(237)	(240)	(83)
Total other income (expenses), net										42	(237)	(240)	(83)
(Loss) income before income tax expense										42	(237)	(240)	(83)
Less: Income tax (benefit) expense										0	0	0	0
Net income (loss)										42	(237)	(240)	(83)
Less: Net (loss) income attributable to non-controlling interests										0	0	0	0
Net income attributable to Successor/Predecessor										$ 42	$ (237)	$ (240)	$ (83)