Guarantor Financial Statement Information - Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jul. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 198
Restricted cash	332
Mortgage servicing rights	3,500
Advances and other receivables, net	1,174
Reverse mortgage interests, net	8,886
Mortgage loans held for sale at fair value	1,681
Mortgage loans held for investment, $122 and $0 at fair value, respectively	122
Property and equipment, net	102
Deferred tax asset	934
Other assets	799
Investment in subsidiaries	0
Total assets	17,728
Liabilities and Stockholders' Equity
Unsecured senior notes, net	2,457
Advance facilities	596
Warehouse facilities	2,888
Payables and accrued liabilities	1,342
MSR related liabilities - nonrecourse at fair value	1,123
Mortgage servicing liabilities	79
Other nonrecourse debt, net	7,165
Payables to affiliates	0
Total liabilities	15,650
Total stockholders' equity	2,078	$ 1,056
Total liabilities and stockholders' equity	17,728
Predecessor
Assets
Cash and cash equivalents		166	$ 215	$ 224
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, $122 and $0 at fair value, respectively			139
Property and equipment, net			121
Deferred tax asset			0
Other assets			679
Investment in subsidiaries			0
Total assets		17,026	18,036	18,004
Liabilities and Stockholders' Equity
Unsecured senior notes, net			1,874
Advance facilities			855
Warehouse facilities			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	$ 1,677	$ 1,683
Total liabilities and stockholders' equity			18,036
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, $122 and $0 at fair value, respectively	0
Property and equipment, net	0
Deferred tax asset	0
Other assets	(686)
Investment in subsidiaries	(3,502)
Total assets	(4,188)
Liabilities and Stockholders' Equity
Unsecured senior notes, net	0
Advance facilities	0
Warehouse facilities	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	(686)
Total liabilities	(686)
Total stockholders' equity	(3,502)
Total liabilities and stockholders' equity	(4,188)
Eliminations | Predecessor
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, $122 and $0 at fair value, respectively			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			0
Warehouse facilities			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)
Mr. Cooper | Reportable entities
Assets
Cash and cash equivalents	5
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, $122 and $0 at fair value, respectively	0
Property and equipment, net	0
Deferred tax asset	990
Other assets	1
Investment in subsidiaries	2,916
Total assets	3,912
Liabilities and Stockholders' Equity
Unsecured senior notes, net	1,658
Advance facilities	0
Warehouse facilities	0
Payables and accrued liabilities	32
MSR related liabilities - nonrecourse at fair value	0
Mortgage servicing liabilities	0
Other nonrecourse debt, net	0
Payables to affiliates	144
Total liabilities	1,834
Total stockholders' equity	2,078
Total liabilities and stockholders' equity	3,912
Mr. Cooper | Reportable entities | Predecessor
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, $122 and $0 at fair value, respectively			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			0
Warehouse facilities			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
Issuer | Reportable entities
Assets
Cash and cash equivalents	164
Restricted cash	168
Mortgage servicing rights	3,462
Advances and other receivables, net	1,174
Reverse mortgage interests, net	7,764
Mortgage loans held for sale at fair value	1,681
Mortgage loans held for investment, $122 and $0 at fair value, respectively	1
Property and equipment, net	85
Deferred tax asset	(49)
Other assets	671
Investment in subsidiaries	586
Total assets	15,707
Liabilities and Stockholders' Equity
Unsecured senior notes, net	799
Advance facilities	33
Warehouse facilities	2,888
Payables and accrued liabilities	1,244
MSR related liabilities - nonrecourse at fair value	1,103
Mortgage servicing liabilities	79
Other nonrecourse debt, net	6,103
Payables to affiliates	542
Total liabilities	12,791
Total stockholders' equity	2,916
Total liabilities and stockholders' equity	15,707
Issuer | Reportable entities | Predecessor
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, $122 and $0 at fair value, respectively			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			106
Warehouse facilities			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
Guarantor (Subsidiaries of Issuer) | Reportable entities
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, $122 and $0 at fair value, respectively	0
Property and equipment, net	0
Deferred tax asset	0
Other assets	197
Investment in subsidiaries	0
Total assets	198
Liabilities and Stockholders' Equity
Unsecured senior notes, net	0
Advance facilities	0
Warehouse facilities	0
Payables and accrued liabilities	2
MSR related liabilities - nonrecourse at fair value	0
Mortgage servicing liabilities	0
Other nonrecourse debt, net	0
Payables to affiliates	0
Total liabilities	2
Total stockholders' equity	196
Total liabilities and stockholders' equity	198
Guarantor (Subsidiaries of Issuer) | Reportable entities | Predecessor
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, $122 and $0 at fair value, respectively			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			0
Warehouse facilities			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
Non-Guarantor (Subsidiaries of Issuer) | Reportable entities
Assets
Cash and cash equivalents	28
Restricted cash	164
Mortgage servicing rights	38
Advances and other receivables, net	0
Reverse mortgage interests, net	1,122
Mortgage loans held for sale at fair value	0
Mortgage loans held for investment, $122 and $0 at fair value, respectively	121
Property and equipment, net	17
Deferred tax asset	(7)
Other assets	616
Investment in subsidiaries	0
Total assets	2,099
Liabilities and Stockholders' Equity
Unsecured senior notes, net	0
Advance facilities	563
Warehouse facilities	0
Payables and accrued liabilities	64
MSR related liabilities - nonrecourse at fair value	20
Mortgage servicing liabilities	0
Other nonrecourse debt, net	1,062
Payables to affiliates	0
Total liabilities	1,709
Total stockholders' equity	390
Total liabilities and stockholders' equity	$ 2,099
Non-Guarantor (Subsidiaries of Issuer) | Reportable entities | Predecessor
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, $122 and $0 at fair value, respectively			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			749
Warehouse facilities			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