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, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements
Service related, net		$ 259	$ 159							$ 418
Net gain on mortgage loans held for sale		83	93							176
Total revenues		342	252							594
Expenses:
Salaries, wages benefits										337
General and administrative										370
Total expenses		275	432							707
Other income (expenses):
Interest income										256
Interest expense										(293)
Other income (expenses)										13
Gain (loss) from subsidiaries										0
Total other income (expenses), net		(26)	2							(24)
(Loss) income before income tax (benefit) expense		41	(178)							(137)
Less: Income tax (benefit) expense		(979)	(42)							(1,021)
Net income (loss)		1,020	(136)							884
Less: Net income (loss) attributable to non-controlling interests		0	0							0
Net income attributable to Successor/Predecessor		$ 1,020	$ (136)							884
Reportable legal entities | Mr. Cooper
Condensed Financial Statements
Service related, net										0
Net gain on mortgage loans held for sale										0
Total revenues										0
Expenses:
Salaries, wages benefits										1
General and administrative										0
Total expenses										1
Other income (expenses):
Interest income										0
Interest expense										(64)
Other income (expenses)										1
Gain (loss) from subsidiaries										(44)
Total other income (expenses), net										(107)
(Loss) income before income tax (benefit) expense										(108)
Less: Income tax (benefit) expense										(992)
Net income (loss)										884
Less: Net income (loss) attributable to non-controlling interests										0
Net income attributable to Successor/Predecessor										884
Reportable legal entities | Issuer
Condensed Financial Statements
Service related, net										233
Net gain on mortgage loans held for sale										175
Total revenues										408
Expenses:
Salaries, wages benefits										258
General and administrative										262
Total expenses										520
Other income (expenses):
Interest income										237
Interest expense										(211)
Other income (expenses)										11
Gain (loss) from subsidiaries										2
Total other income (expenses), net										39
(Loss) income before income tax (benefit) expense										(73)
Less: Income tax (benefit) expense										(29)
Net income (loss)										(44)
Less: Net income (loss) attributable to non-controlling interests										0
Net income attributable to Successor/Predecessor										(44)
Reportable legal entities | Guarantor (Subsidiaries of Issuer)
Condensed Financial Statements
Service related, net										9
Net gain on mortgage loans held for sale										0
Total revenues										9
Expenses:
Salaries, wages benefits										2
General and administrative										1
Total expenses										3
Other income (expenses):
Interest income										0
Interest expense										0
Other income (expenses)										0
Gain (loss) from subsidiaries										0
Total other income (expenses), net										0
(Loss) income before income tax (benefit) expense										6
Less: Income tax (benefit) expense										0
Net income (loss)										6
Less: Net income (loss) attributable to non-controlling interests										0
Net income attributable to Successor/Predecessor										6
Reportable legal entities | Non-Guarantor (Subsidiaries of Issuer)
Condensed Financial Statements
Service related, net										176
Net gain on mortgage loans held for sale										1
Total revenues										177
Expenses:
Salaries, wages benefits										76
General and administrative										107
Total expenses										183
Other income (expenses):
Interest income										19
Interest expense										(18)
Other income (expenses)										1
Gain (loss) from subsidiaries										0
Total other income (expenses), net										2
(Loss) income before income tax (benefit) expense										(4)
Less: Income tax (benefit) expense										0
Net income (loss)										(4)
Less: Net income (loss) attributable to non-controlling interests										0
Net income attributable to Successor/Predecessor										(4)
Eliminations
Condensed Financial Statements
Service related, net										0
Net gain on mortgage loans held for sale										0
Total revenues										0
Expenses:
Salaries, wages benefits										0
General and administrative										0
Total expenses										0
Other income (expenses):
Interest income										0
Interest expense										0
Other income (expenses)										0
Gain (loss) from subsidiaries										42
Total other income (expenses), net										42
(Loss) income before income tax (benefit) expense										42
Less: Income tax (benefit) expense										0
Net income (loss)										42
Less: Net income (loss) attributable to non-controlling interests										0
Net income attributable to Successor/Predecessor										$ 42
Predecessor
Condensed Financial Statements
Service related, net	$ 120			$ 317	$ 464	$ 295	$ 252	$ 213	$ 283		$ 901	$ 1,043	$ 1,122
Net gain on mortgage loans held for sale	44			127	124	142	154	167	144		295	607	793
Total revenues	164			444	588	437	406	380	427		1,196	1,650	1,915
Expenses:
Salaries, wages benefits											426	742	813
General and administrative											519	733	831
Total expenses	242			339	364	366	368	369	372		945	1,475	1,644
Other income (expenses):
Interest income											333	597	425
Interest expense											(388)	(731)	(665)
Other income (expenses)											6	3	(2)
Gain (loss) from subsidiaries											0	0	0
Total other income (expenses), net	(5)			(26)	(18)	(13)	(26)	(40)	(52)		(49)	(131)	(242)
(Loss) income before income tax (benefit) expense	(83)			79	206	58	12	(29)	3		202	44	29
Less: Income tax (benefit) expense	(19)			21	46	17	5	(10)	1		48	13	13
Net income (loss)	(64)			58	160	41	7	(19)	2		154	31	16
Less: Net income (loss) attributable to non-controlling interests	0			0	0	0	0	1	0		0	1	(3)
Net income attributable to Successor/Predecessor	$ (64)			$ 58	$ 160	$ 41	$ 7	$ (20)	$ 2		154	30	19
Predecessor | Reportable legal entities | Mr. Cooper
Condensed Financial Statements
Service related, net											0	0	0
Net gain on mortgage loans held for sale											0	0	0
Total revenues											0	0	0
Expenses:
Salaries, wages benefits											0	0	0
General and administrative											27	0	0
Total expenses											27	0	0
Other income (expenses):
Interest income											0	0	0
Interest expense											0	0	0
Other income (expenses)											0	0	0
Gain (loss) from subsidiaries											181	30	19
Total other income (expenses), net											181	30	19
(Loss) income before income tax (benefit) expense											154	30	19
Less: Income tax (benefit) expense											0	0	0
Net income (loss)											154	30	19
Less: Net income (loss) attributable to non-controlling interests											0	0	0
Net income attributable to Successor/Predecessor											154	30	19
Predecessor | Reportable legal entities | Issuer
Condensed Financial Statements
Service related, net											732	717	658
Net gain on mortgage loans held for sale											295	606	764
Total revenues											1,027	1,323	1,422
Expenses:
Salaries, wages benefits											359	605	601
General and administrative											427	590	617
Total expenses											786	1,195	1,218
Other income (expenses):
Interest income											299	544	375
Interest expense											(364)	(675)	(592)
Other income (expenses)											(3)	(6)	(2)
Gain (loss) from subsidiaries											56	53	44
Total other income (expenses), net											(12)	(84)	(175)
(Loss) income before income tax (benefit) expense											229	44	29
Less: Income tax (benefit) expense											48	13	13
Net income (loss)											181	31	16
Less: Net income (loss) attributable to non-controlling interests											0	1	(3)
Net income attributable to Successor/Predecessor											181	30	19
Predecessor | Reportable legal entities | Guarantor (Subsidiaries of Issuer)
Condensed Financial Statements
Service related, net											16	28	33
Net gain on mortgage loans held for sale											0	0	0
Total revenues											16	28	33
Expenses:
Salaries, wages benefits											3	5	5
General and administrative											1	11	8
Total expenses											4	16	13
Other income (expenses):
Interest income											0	0	0
Interest expense											0	0	0
Other income (expenses)											0	0	0
Gain (loss) from subsidiaries											0	0	0
Total other income (expenses), net											0	0	0
(Loss) income before income tax (benefit) expense											12	12	20
Less: Income tax (benefit) expense											0	0	0
Net income (loss)											12	12	20
Less: Net income (loss) attributable to non-controlling interests											0	0	0
Net income attributable to Successor/Predecessor											12	12	20
Predecessor | Reportable legal entities | Non-Guarantor (Subsidiaries of Issuer)
Condensed Financial Statements
Service related, net											153	298	431
Net gain on mortgage loans held for sale											0	1	29
Total revenues											153	299	460
Expenses:
Salaries, wages benefits											64	132	207
General and administrative											64	132	206
Total expenses											128	264	413
Other income (expenses):
Interest income											34	53	50
Interest expense											(24)	(56)	(73)
Other income (expenses)											9	9	0
Gain (loss) from subsidiaries											0	0	0
Total other income (expenses), net											19	6	(23)
(Loss) income before income tax (benefit) expense											44	41	24
Less: Income tax (benefit) expense											0	0	0
Net income (loss)											44	41	24
Less: Net income (loss) attributable to non-controlling interests											0	0	0
Net income attributable to Successor/Predecessor											44	41	24
Predecessor | Eliminations
Condensed Financial Statements
Service related, net											0	0	0
Net gain on mortgage loans held for sale											0	0	0
Total revenues											0	0	0
Expenses:
Salaries, wages benefits											0	0	0
General and administrative											0	0	0
Total expenses											0	0	0
Other income (expenses):
Interest income											0	0	0
Interest expense											0	0	0
Other income (expenses)											0	0	0
Gain (loss) from subsidiaries											(237)	(83)	(63)
Total other income (expenses), net											(237)	(83)	(63)
(Loss) income before income tax (benefit) expense											(237)	(83)	(63)
Less: Income tax (benefit) expense											0	0	0
Net income (loss)											(237)	(83)	(63)
Less: Net income (loss) attributable to non-controlling interests											0	0	0
Net income attributable to Successor/Predecessor											$ (237)	$ (83)	$ (63)