Guarantor Financial Statement Information - Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 242
Restricted cash	319
Mortgage servicing rights	3,676
Advances and other receivables, net	1,194
Reverse mortgage interests, net	7,934
Mortgage loans held for sale at fair value	1,631
Mortgage loans held for investment, net	119
Property and equipment, net	96
Deferred tax asset, net	967
Other assets	795
Investment in subsidiaries	0
Total assets	16,973
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	2,459
Advance facilities, net	595
Warehouse facilities, net	2,349
Payables and accrued liabilities	1,543
MSR related liabilities - nonrecourse at fair value	1,216
Mortgage servicing liabilities	71
Other nonrecourse debt, net	6,795
Payables to affiliates	0
Total liabilities	15,028
Total stockholders’ equity	1,945	$ 1,056
Total liabilities and stockholders’ equity	16,973
Reportable legal entities | Mr. Cooper
Assets
Cash and cash equivalents	0
Restricted cash	0
Mortgage servicing rights	0
Advances and other receivables, net	0
Reverse mortgage interests, net	0
Mortgage loans held for sale at fair value	0
Mortgage loans held for investment, net	0
Property and equipment, net	0
Deferred tax asset, net	973
Other assets	0
Investment in subsidiaries	2,820
Total assets	3,793
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	1,660
Advance facilities, net	0
Warehouse facilities, net	0
Payables and accrued liabilities	49
MSR related liabilities - nonrecourse at fair value	0
Mortgage servicing liabilities	0
Other nonrecourse debt, net	0
Payables to affiliates	139
Total liabilities	1,848
Total stockholders’ equity	1,945
Total liabilities and stockholders’ equity	3,793
Reportable legal entities | Issuer
Assets
Cash and cash equivalents	193
Restricted cash	186
Mortgage servicing rights	3,644
Advances and other receivables, net	1,194
Reverse mortgage interests, net	6,770
Mortgage loans held for sale at fair value	1,631
Mortgage loans held for investment, net	1
Property and equipment, net	84
Deferred tax asset, net	0
Other assets	660
Investment in subsidiaries	601
Total assets	14,964
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	799
Advance facilities, net	90
Warehouse facilities, net	2,349
Payables and accrued liabilities	1,413
MSR related liabilities - nonrecourse at fair value	1,197
Mortgage servicing liabilities	71
Other nonrecourse debt, net	5,676
Payables to affiliates	549
Total liabilities	12,144
Total stockholders’ equity	2,820
Total liabilities and stockholders’ equity	14,964
Reportable legal entities | Guarantor (Subsidiaries of Issuer)
Assets
Cash and cash equivalents	1
Restricted cash	0
Mortgage servicing rights	0
Advances and other receivables, net	0
Reverse mortgage interests, net	0
Mortgage loans held for sale at fair value	0
Mortgage loans held for investment, net	0
Property and equipment, net	0
Deferred tax asset, net	0
Other assets	202
Investment in subsidiaries	0
Total assets	203
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	0
Advance facilities, net	0
Warehouse facilities, net	0
Payables and accrued liabilities	1
MSR related liabilities - nonrecourse at fair value	0
Mortgage servicing liabilities	0
Other nonrecourse debt, net	0
Payables to affiliates	0
Total liabilities	1
Total stockholders’ equity	202
Total liabilities and stockholders’ equity	203
Reportable legal entities | Non-Guarantor (Subsidiaries of Issuer)
Assets
Cash and cash equivalents	48
Restricted cash	133
Mortgage servicing rights	32
Advances and other receivables, net	0
Reverse mortgage interests, net	1,164
Mortgage loans held for sale at fair value	0
Mortgage loans held for investment, net	118
Property and equipment, net	12
Deferred tax asset, net	(6)
Other assets	621
Investment in subsidiaries	0
Total assets	2,122
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	0
Advance facilities, net	505
Warehouse facilities, net	0
Payables and accrued liabilities	80
MSR related liabilities - nonrecourse at fair value	19
Mortgage servicing liabilities	0
Other nonrecourse debt, net	1,119
Payables to affiliates	0
Total liabilities	1,723
Total stockholders’ equity	399
Total liabilities and stockholders’ equity	2,122
Eliminations
Assets
Cash and cash equivalents	0
Restricted cash	0
Mortgage servicing rights	0
Advances and other receivables, net	0
Reverse mortgage interests, net	0
Mortgage loans held for sale at fair value	0
Mortgage loans held for investment, net	0
Property and equipment, net	0
Deferred tax asset, net	0
Other assets	(688)
Investment in subsidiaries	(3,421)
Total assets	(4,109)
Liabilities and Stockholders’ Equity
Unsecured senior notes, net	0
Advance facilities, net	0
Warehouse facilities, net	0
Payables and accrued liabilities
MSR related liabilities - nonrecourse at fair value	0
Mortgage servicing liabilities	0
Other nonrecourse debt, net	0
Payables to affiliates	(688)
Total liabilities	(688)
Total stockholders’ equity	(3,421)
Total liabilities and stockholders’ equity	$ (4,109)
Predecessor
Assets
Cash and cash equivalents		166	$ 215	$ 489
Restricted cash			360
Mortgage servicing rights			2,941
Advances and other receivables, net			1,706
Reverse mortgage interests, net			9,984
Mortgage loans held for sale at fair value			1,891
Mortgage loans held for investment, net			139
Property and equipment, net			121
Deferred tax asset, net			0
Other assets			679
Investment in subsidiaries			0
Total assets		17,026	18,036	19,593
Liabilities and Stockholders’ Equity
Unsecured senior notes, net			1,874
Advance facilities, net			855
Warehouse facilities, net			3,285
Payables and accrued liabilities			1,239
MSR related liabilities - nonrecourse at fair value			1,006
Mortgage servicing liabilities			41
Other nonrecourse debt, net			8,014
Payables to affiliates			0
Total liabilities			16,314
Total stockholders’ equity		$ 1,883	1,722	$ 1,683	$ 1,767
Total liabilities and stockholders’ equity			18,036
Predecessor | Reportable legal entities | Mr. Cooper
Assets
Cash and cash equivalents			0
Restricted cash			0
Mortgage servicing rights			0
Advances and other receivables, net			0
Reverse mortgage interests, net			0
Mortgage loans held for sale at fair value			0
Mortgage loans held for investment, net			0
Property and equipment, net			0
Other assets			0
Investment in subsidiaries			1,846
Total assets			1,846
Liabilities and Stockholders’ Equity
Unsecured senior notes, net			0
Advance facilities, net			0
Warehouse facilities, net			0
Payables and accrued liabilities			0
MSR related liabilities - nonrecourse at fair value			0
Mortgage servicing liabilities			0
Other nonrecourse debt, net			0
Payables to affiliates			124
Total liabilities			124
Total stockholders’ equity			1,722
Total liabilities and stockholders’ equity			1,846
Predecessor | Reportable legal entities | Issuer
Assets
Cash and cash equivalents			195
Restricted cash			228
Mortgage servicing rights			2,910
Advances and other receivables, net			1,706
Reverse mortgage interests, net			9,110
Mortgage loans held for sale at fair value			1,891
Mortgage loans held for investment, net			1
Property and equipment, net			102
Other assets			585
Investment in subsidiaries			522
Total assets			17,250
Liabilities and Stockholders’ Equity
Unsecured senior notes, net			1,874
Advance facilities, net			106
Warehouse facilities, net			3,285
Payables and accrued liabilities			1,202
MSR related liabilities - nonrecourse at fair value			987
Mortgage servicing liabilities			41
Other nonrecourse debt, net			7,167
Payables to affiliates			742
Total liabilities			15,404
Total stockholders’ equity			1,846
Total liabilities and stockholders’ equity			17,250
Predecessor | Reportable legal entities | Guarantor (Subsidiaries of Issuer)
Assets
Cash and cash equivalents			1
Restricted cash			0
Mortgage servicing rights			0
Advances and other receivables, net			0
Reverse mortgage interests, net			0
Mortgage loans held for sale at fair value			0
Mortgage loans held for investment, net			0
Property and equipment, net			0
Other assets			182
Investment in subsidiaries			0
Total assets			183
Liabilities and Stockholders’ Equity
Unsecured senior notes, net			0
Advance facilities, net			0
Warehouse facilities, net			0
Payables and accrued liabilities			1
MSR related liabilities - nonrecourse at fair value			0
Mortgage servicing liabilities			0
Other nonrecourse debt, net			0
Payables to affiliates			0
Total liabilities			1
Total stockholders’ equity			182
Total liabilities and stockholders’ equity			183
Predecessor | Reportable legal entities | Non-Guarantor (Subsidiaries of Issuer)
Assets
Cash and cash equivalents			19
Restricted cash			132
Mortgage servicing rights			31
Advances and other receivables, net			0
Reverse mortgage interests, net			874
Mortgage loans held for sale at fair value			0
Mortgage loans held for investment, net			138
Property and equipment, net			19
Other assets			779
Investment in subsidiaries			0
Total assets			1,992
Liabilities and Stockholders’ Equity
Unsecured senior notes, net			0
Advance facilities, net			749
Warehouse facilities, net			0
Payables and accrued liabilities			36
MSR related liabilities - nonrecourse at fair value			19
Mortgage servicing liabilities			0
Other nonrecourse debt, net			847
Payables to affiliates			1
Total liabilities			1,652
Total stockholders’ equity			340
Total liabilities and stockholders’ equity			1,992
Predecessor | Eliminations
Assets
Cash and cash equivalents			0
Restricted cash			0
Mortgage servicing rights			0
Advances and other receivables, net			0
Reverse mortgage interests, net			0
Mortgage loans held for sale at fair value			0
Mortgage loans held for investment, net			0
Property and equipment, net			0
Other assets			(867)
Investment in subsidiaries			(2,368)
Total assets			(3,235)
Liabilities and Stockholders’ Equity
Unsecured senior notes, net			0
Advance facilities, net			0
Warehouse facilities, net			0
Payables and accrued liabilities			0
MSR related liabilities - nonrecourse at fair value			0
Mortgage servicing liabilities			0
Other nonrecourse debt, net			0
Payables to affiliates			(867)
Total liabilities			(867)
Total stockholders’ equity			(2,368)
Total liabilities and stockholders’ equity			$ (3,235)