Guarantor Financial Statement Information - Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 245		$ 242	$ 185
Restricted cash	304		319
Mortgage servicing rights	3,511		3,676
Advances and other receivables, net	1,000		1,194
Reverse mortgage interests, net	7,110		7,934
Mortgage loans held for sale at fair value	3,422		1,631
Mortgage loans held for investment at fair value	114		119
Property and equipment, net	115		96
Deferred tax asset, net	1,055		967
Other assets	1,529		795
Investment in subsidiaries	0		0
Total assets	18,405		16,973	17,190
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	2,462		2,459
Advance facilities	567		595
Warehouse facilities	4,045		2,349
Payables and other liabilities	2,116		1,543
MSR related liabilities - nonrecourse at fair value	1,472		1,216
Mortgage servicing liabilities	80		71
Other nonrecourse debt, net	5,985		6,795
Payables to affiliates	0		0
Total liabilities	16,727		15,028
Total stockholders' equity	1,678	$ 1,761	1,945	$ 1,941	$ 1,882	$ 1,722
Total liabilities and stockholders’ equity	18,405		16,973
Eliminations
Assets
Cash and cash equivalents	0		0
Restricted cash	0		0
Mortgage servicing rights	0		0
Advances and other receivables, net	0		0
Reverse mortgage interests, net	0		0
Mortgage loans held for sale at fair value	0		0
Mortgage loans held for investment at fair value	0		0
Property and equipment, net	0		0
Deferred tax asset, net	0		0
Other assets	(739)		(688)
Investment in subsidiaries	(3,169)		(3,421)
Total assets	(3,908)		(4,109)
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	0		0
Advance facilities	0		0
Warehouse facilities	0		0
Payables and other liabilities	0		0
MSR related liabilities - nonrecourse at fair value	0		0
Mortgage servicing liabilities	0		0
Other nonrecourse debt, net	0		0
Payables to affiliates	(739)		(688)
Total liabilities	(739)		(688)
Total stockholders' equity	(3,169)		(3,421)
Total liabilities and stockholders’ equity	(3,908)		(4,109)
Mr. Cooper | Reportable entities
Assets
Cash and cash equivalents	0		0
Restricted cash	0		0
Mortgage servicing rights	0		0
Advances and other receivables, net	0		0
Reverse mortgage interests, net	0		0
Mortgage loans held for sale at fair value	0		0
Mortgage loans held for investment at fair value	0		0
Property and equipment, net	0		0
Deferred tax asset, net	984		973
Other assets	0		0
Investment in subsidiaries	2,557		2,820
Total assets	3,541		3,793
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	1,663		1,660
Advance facilities	0		0
Warehouse facilities	0		0
Payables and other liabilities	59		49
MSR related liabilities - nonrecourse at fair value	0		0
Mortgage servicing liabilities	0		0
Other nonrecourse debt, net	0		0
Payables to affiliates	141		139
Total liabilities	1,863		1,848
Total stockholders' equity	1,678		1,945
Total liabilities and stockholders’ equity	3,541		3,793
Issuer | Reportable entities
Assets
Cash and cash equivalents	215		193
Restricted cash	204		186
Mortgage servicing rights	3,484		3,644
Advances and other receivables, net	1,000		1,194
Reverse mortgage interests, net	6,003		6,770
Mortgage loans held for sale at fair value	3,422		1,631
Mortgage loans held for investment at fair value	2		1
Property and equipment, net	99		84
Deferred tax asset, net	69		0
Other assets	1,399		660
Investment in subsidiaries	612		601
Total assets	16,509		14,964
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	799		799
Advance facilities	89		90
Warehouse facilities	4,045		2,349
Payables and other liabilities	1,999		1,413
MSR related liabilities - nonrecourse at fair value	1,456		1,197
Mortgage servicing liabilities	80		71
Other nonrecourse debt, net	4,890		5,676
Payables to affiliates	594		549
Total liabilities	13,952		12,144
Total stockholders' equity	2,557		2,820
Total liabilities and stockholders’ equity	16,509		14,964
Guarantor (Subsidiaries of Issuer) | Reportable entities
Assets
Cash and cash equivalents	1		1
Restricted cash	0		0
Mortgage servicing rights	0		0
Advances and other receivables, net	0		0
Reverse mortgage interests, net	0		0
Mortgage loans held for sale at fair value	0		0
Mortgage loans held for investment at fair value	0		0
Property and equipment, net	0		0
Deferred tax asset, net	0		0
Other assets	208		202
Investment in subsidiaries	0		0
Total assets	209		203
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	0		0
Advance facilities	0		0
Warehouse facilities	0		0
Payables and other liabilities	2		1
MSR related liabilities - nonrecourse at fair value	0		0
Mortgage servicing liabilities	0		0
Other nonrecourse debt, net	0		0
Payables to affiliates	0		0
Total liabilities	2		1
Total stockholders' equity	207		202
Total liabilities and stockholders’ equity	209		203
Non-Guarantor (Subsidiaries of Issuer) | Reportable entities
Assets
Cash and cash equivalents	29		48
Restricted cash	100		133
Mortgage servicing rights	27		32
Advances and other receivables, net	0		0
Reverse mortgage interests, net	1,107		1,164
Mortgage loans held for sale at fair value	0		0
Mortgage loans held for investment at fair value	112		118
Property and equipment, net	16		12
Deferred tax asset, net	2		(6)
Other assets	661		621
Investment in subsidiaries	0		0
Total assets	2,054		2,122
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	0		0
Advance facilities	478		505
Warehouse facilities	0		0
Payables and other liabilities	56		80
MSR related liabilities - nonrecourse at fair value	16		19
Mortgage servicing liabilities	0		0
Other nonrecourse debt, net	1,095		1,119
Payables to affiliates	4		0
Total liabilities	1,649		1,723
Total stockholders' equity	405		399
Total liabilities and stockholders’ equity	$ 2,054		$ 2,122