Guarantor Financial Statement Information - Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jul. 31, 2018
Assets
Cash and cash equivalents	$ 371		$ 242	$ 198
Restricted cash	271		319
Mortgage servicing rights	3,346		3,676
Advances and other receivables, net	967		1,194
Reverse mortgage interests, net	6,662		7,934
Mortgage loans held for sale at fair value	4,267		1,631
Mortgage loans held for investment at fair value	0		119
Property and equipment, net	113		96
Deferred tax asset, net	1,032		967
Other assets	1,449		795
Investment in subsidiaries	0		0
Total assets	18,478		16,973	17,728
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	2,464		2,459
Advance facilities	513		595
Warehouse facilities	4,802		2,349
Payables and other liabilities	2,002		1,543
MSR related liabilities - nonrecourse at fair value	1,328		1,216
Mortgage servicing liabilities	69		71
Other nonrecourse debt, net	5,533		6,795
Payables to affiliates	0		0
Total liabilities	16,711		15,028
Total stockholders’ equity	1,767	$ 1,678	1,945	$ 2,078	$ 1,056
Total liabilities and stockholders’ equity	18,478		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
Property and equipment, net	0		0
Deferred tax asset, net	0		0
Other assets	(895)		(688)
Investment in subsidiaries	(3,294)		(3,421)
Total assets	(4,189)		(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	(895)		(688)
Total liabilities	(895)		(688)
Total stockholders’ equity	(3,294)		(3,421)
Total liabilities and stockholders’ equity	(4,189)		(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
Property and equipment, net	0		0
Deferred tax asset, net	984		973
Other assets	0		0
Investment in subsidiaries	2,612		2,820
Total assets	3,596		3,793
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	1,665		1,660
Advance facilities	0		0
Warehouse facilities	0		0
Payables and other liabilities	23		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	1,829		1,848
Total stockholders’ equity	1,767		1,945
Total liabilities and stockholders’ equity	3,596		3,793
Issuer | Reportable entities
Assets
Cash and cash equivalents	331		193
Restricted cash	155		186
Mortgage servicing rights	3,322		3,644
Advances and other receivables, net	966		1,194
Reverse mortgage interests, net	5,733		6,770
Mortgage loans held for sale at fair value	4,267		1,631
Mortgage loans held for investment at fair value			1
Property and equipment, net	94		84
Deferred tax asset, net	46		0
Other assets	1,317		660
Investment in subsidiaries	682		601
Total assets	16,913		14,964
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	799		799
Advance facilities	64		90
Warehouse facilities	4,802		2,349
Payables and other liabilities	1,905		1,413
MSR related liabilities - nonrecourse at fair value	1,313		1,197
Mortgage servicing liabilities	69		71
Other nonrecourse debt, net	4,596		5,676
Payables to affiliates	753		549
Total liabilities	14,301		12,144
Total stockholders’ equity	2,612		2,820
Total liabilities and stockholders’ equity	16,913		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
Property and equipment, net	0		0
Deferred tax asset, net	0		0
Other assets	213		202
Investment in subsidiaries	0		0
Total assets	214		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	212		202
Total liabilities and stockholders’ equity	214		203
Non-Guarantor (Subsidiaries of Issuer) | Reportable entities
Assets
Cash and cash equivalents	39		48
Restricted cash	116		133
Mortgage servicing rights	24		32
Advances and other receivables, net	1		0
Reverse mortgage interests, net	929		1,164
Mortgage loans held for sale at fair value	0		0
Mortgage loans held for investment at fair value			118
Property and equipment, net	19		12
Deferred tax asset, net	2		(6)
Other assets	814		621
Investment in subsidiaries	0		0
Total assets	1,944		2,122
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	0		0
Advance facilities	449		505
Warehouse facilities	0		0
Payables and other liabilities	72		80
MSR related liabilities - nonrecourse at fair value	15		19
Mortgage servicing liabilities	0		0
Other nonrecourse debt, net	937		1,119
Payables to affiliates	1		0
Total liabilities	1,474		1,723
Total stockholders’ equity	470		399
Total liabilities and stockholders’ equity	$ 1,944		$ 2,122