Line of Credit Facility, Accordion Feature, Higher Borrowing Capacity Option

No definition available.

Name:	nav_LineofCreditFacilityAccordionFeatureHigherBorrowingCapacityOption
Namespace Prefix:	nav_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(b))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.9-06)
-URI http://asc.fasb.org/extlink&oid=6882215&loc=d3e537971-122884

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentPeriodicPaymentPrincipal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13476-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=nav_VfnFacilityMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nav_BankFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=nav_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
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Data Type:	na
Balance Type:
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- Details

Name:	nav_InstallmentPaymentsBySetAxis=nav_InstallmentPaymentsSetTwoMember
Namespace Prefix:
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Balance Type:
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Debt - Narrative (Details) - USD ($)	1 Months Ended		3 Months Ended	9 Months Ended
Debt - Narrative (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2011	Jul. 31, 2016	Jul. 31, 2016	May 31, 2016	Apr. 30, 2016	Feb. 29, 2016
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 100,000,000
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			$ 50,000,000	$ 80,000,000
Financial Services Operations [Member] \| VFN Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 375,000,000	$ 500,000,000
Revolving Credit Facility [Member] \| Financial Services Operations [Member] \| Bank Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 500,000,000			$ 400,000,000
Line of Credit Facility, Fair Value of Amount Outstanding			300,000,000	300,000,000
Line of Credit Facility, Accordion Feature, Higher Borrowing Capacity Option					$ 700,000,000
Term Loan [Member] \| Financial Services Operations [Member] \| Bank Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding			$ 221,000,000	$ 221,000,000
Scenario, Forecast [Member] \| Revolving Credit Facility [Member] \| Financial Services Operations [Member] \| Bank Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 275,000,000
Scenario, Forecast [Member] \| Term Loan [Member] \| Financial Services Operations [Member] \| Bank Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	82,000,000
Installment Payments Set Two [Member] \| Term Loan [Member] \| Financial Services Operations [Member] \| Bank Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal		$ 9,000,000
Installment Payments Set Two [Member] \| Scenario, Forecast [Member] \| Term Loan [Member] \| Financial Services Operations [Member] \| Bank Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 2,000,000