| **Fair Value Measurements - Narrative (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended                                                                                                                 |                                                                                                                                 |
|--------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------|
||
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]** |                                                                                                                           |                                                                                                                            |   |
| Asset impairment charges                                                                         | $ 7us-gaap_AssetImpairmentCharges                                                                                              | $ 18us-gaap_AssetImpairmentCharges                                                                                              |   |
| Goodwill                                                                                         | 38us-gaap_Goodwill                                                                                                             |                                                                                                                            | 38us-gaap_Goodwill |
| Cash and Cash Equivalents, Maturity Term                                                         | 90 days                                                                                                                        |                                                                                                                            |   |
| Marketable Securities, Maturity Term                                                             | 90 days                                                                                                                        |                                                                                                                            |   |
| Brazilian Reporting Unit [Member]                                                                |                                                                                                                           |                                                                                                                            |   |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]** |                                                                                                                           |                                                                                                                            |   |
| Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)                           | 0us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill/ nav_ReportingUnitAxis= nav_BrazilianReportingUnitMember | 16us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill/ nav_ReportingUnitAxis= nav_BrazilianReportingUnitMember |   |
| North America Truck [Member]                                                                     |                                                                                                                           |                                                                                                                            |   |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]** |                                                                                                                           |                                                                                                                            |   |
| Asset impairment charges                                                                         | $ 7us-gaap_AssetImpairmentCharges/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember                          | $ 18us-gaap_AssetImpairmentCharges/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember                          |   |

| X                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Maximum maturity term for a cash and cash equivalent instrument
+ References
No definition available.
+ Details**Name:**nav_CashandCashEquivalentsMaturityTerm**Namespace Prefix:**nav_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Maximum maturity term for a marketable security instrument
+ References
No definition available.
+ Details**Name:**nav_MarketableSecuritiesMaturityTerm**Namespace Prefix:**nav_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228
+ Details**Name:**us-gaap_AssetImpairmentCharges**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266
+ Details**Name:**us-gaap_Goodwill**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16373-109275
+ Details**Name:**us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**nav_ReportingUnitAxis=nav_BrazilianReportingUnitMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementBusinessSegmentsAxis=nav_NorthAmericaTruckMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |