[Line Items] for Reverse Mortgage Interest [Table]

No definition available.

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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized

No definition available.

Name:	nsm_ReverseMortgageInterestUnpaidPrincipalBalanceUnsecuritized
Namespace Prefix:	nsm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Funded Draws Not Yet Securitized

No definition available.

Name:	nsm_ReverseMortgageInterestUnpaidPrincipalBalanceUnsecuritizedFundedDrawsNotYetSecuritized
Namespace Prefix:	nsm_
Data Type:	xbrli:monetaryItemType
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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Home Equity Conversion Mortgage Receivables

No definition available.

Name:	nsm_ReverseMortgageInterestUnpaidPrincipalBalanceUnsecuritizedHomeEquityConversionMortgageReceivables
Namespace Prefix:	nsm_
Data Type:	xbrli:monetaryItemType
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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Purchase Discount

No definition available.

Name:	nsm_ReverseMortgageInterestUnpaidPrincipalBalanceUnsecuritizedPurchaseDiscount
Namespace Prefix:	nsm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Real Estate Owned Related Receivables

No definition available.

Name:	nsm_ReverseMortgageInterestUnpaidPrincipalBalanceUnsecuritizedRealEstateOwnedRelatedReceivables
Namespace Prefix:	nsm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Repurchase of Home Equity Conversion Mortgages

No definition available.

Name:	nsm_ReverseMortgageInterestUnpaidPrincipalBalanceUnsecuritizedRepurchaseofHomeEquityConversionMortgages
Namespace Prefix:	nsm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	us-gaap_StatementScenarioAxis=us-gaap_PredecessorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Reverse Mortgage Interests, Net - Unsecurtized Interests (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2017
Reverse Mortgage Interest [Line Items]
Repurchased HECM loans (exceed 98% MCA)	$ 949
HECM related receivables	300
Funded borrower draws not yet securitized	76
REO-related receivables	16
Purchase discount	(122)	$ (173)
Total unsecuritized interests	$ 1,219
Predecessor
Reverse Mortgage Interest [Line Items]
Repurchased HECM loans (exceed 98% MCA)			$ 1,751
HECM related receivables			311
Funded borrower draws not yet securitized			82
REO-related receivables			25
Purchase discount			(89)
Total unsecuritized interests			$ 2,080