Concentrations of Risk - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2013 PrivateSectorCompany PrivateSectorInstitution Clients
Risks And Uncertainties [Abstract]
Net interest margin earned on FFELP Loans portfolio	$ 1,500,000,000
Maintenance fees earned on FFELP Loans	38,000,000
Number of guarantors as clients	15
Total collection revenue from guarantor clients	$ 303,000,000
Number of private sector institutions servicing DSLP	4
Number of private sector companies collecting defaulted direct loans	22

Represents total collection revenue from the company's guarantor clients.

No definition available.

Name:	navi_CollectionRevenueFromGuarantorClients
Namespace Prefix:	navi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the total maintenance fees on FFELP Loans earned during the period.

No definition available.

Name:	navi_MaintenanceFeesEarnedOnFfelpLoans
Namespace Prefix:	navi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Net interest margin on FFELP portfolio.

No definition available.

Name:	navi_NetInterestMarginFfelpPortfolio
Namespace Prefix:	navi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the number of guarantors that the company has as clients.

No definition available.

Name:	navi_NumberOfGuarantorsAsClients
Namespace Prefix:	navi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Number of private sector companies collecting defaulted direct loans.

No definition available.

Name:	navi_NumberOfPrivateSectorCompaniesCollectingDefaultedDirectLoans
Namespace Prefix:	navi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Represents the number of private sector institutions providing servicing for the federal government's Direct Student Loan Program.

No definition available.

Name:	navi_NumberOfPrivateSectorInstitutionsProvidingServicing
Namespace Prefix:	navi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Name:	us-gaap_RisksAndUncertaintiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Period Type:	duration