| **Goodwill and Other Intangible assets, Net Intangible Assets Not Subject to Amortization (Details) - USD ($) $ in Millions** | 3 Months Ended | 12 Months Ended |
|-------------------------------------------------------------------------------------------------------------------------------|----------------|-----------------|
||
| **Indefinite-lived Intangible Assets [Line Items]**                                                                           |           |            |   |   |   |
| Indefinite-Lived Intangible Assets (Excluding Goodwill)                                                                       |           |            | $ 19 | $ 34 |   |
| Franchise Rights [Member]                                                                                                     |           |            |   |   |   |
| **Indefinite-lived Intangible Assets [Line Items]**                                                                           |           |            |   |   |   |
| Indefinite-Lived Intangible Assets (Excluding Goodwill)                                                                       |           |            | 0 | 1 |   |
| Trademarks [Member]                                                                                                           |           |            |   |   |   |
| **Indefinite-lived Intangible Assets [Line Items]**                                                                           |           |            |   |   |   |
| Indefinite-Lived Intangible Assets (Excluding Goodwill)                                                                       |           |            | 19 | 33 |   |
| Brazilian Reporting Unit [Member]                                                                                             |           |            |   |   |   |
| **Indefinite-lived Intangible Assets [Line Items]**                                                                           |           |            |   |   |   |
| Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)                                                        | $ 3            | $ 7             | $ 7 | $ 7 | $ 0 |
| Indefinite-Lived Intangible Assets (Excluding Goodwill)                                                                       | $ 24           | $ 43            |   |   |   |

| 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
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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_IndefiniteLivedIntangibleAssetsByMajorClassLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275
+ Details**Name:**us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_FranchiseRightsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TrademarksMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**nav_ReportingUnitAxis=nav_BrazilianReportingUnitMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |