| **Financial Instruments and Commodity Contracts - Derivative Financial Instruments (Details) - USD ($) $ in Millions** | 12 Months Ended |
|------------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Derivative [Line Items]**                                                                                            |            |   |   |
| Exposure to Credit Risk                                                                                                | $ 1             | $ 1 |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                      | 6               | 4 | $ (2) |
| Interest Rate Cap [Member] | Interest Expense [Member]                                                                 |            |   |   |
| **Derivative [Line Items]**                                                                                            |            |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                      | 1               | (1) | 0 |
| Cross currency swaps | Other Income Expense Net [Member]                                                               |            |   |   |
| **Derivative [Line Items]**                                                                                            |            |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                      | 2               | 3 | 0 |
| Foreign Exchange Contract [Member] | Other Income Expense Net [Member]                                                 |            |   |   |
| **Derivative [Line Items]**                                                                                            |            |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                      | (9)             | (1) | (4) |
| Commodity Contract [Member] | Cost of Sales [Member]                                                                   |            |   |   |
| **Derivative [Line Items]**                                                                                            |            |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                      | $ (12)          | $ (1) | $ (2) |

| X                                                                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Exposure to Credit Risk
+ References
No definition available.
+ Details**Name:**nav_ExposureToCreditRisk**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959
+ Details**Name:**us-gaap_DerivativeGainLossOnDerivativeNet**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| 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_DerivativeLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateCapMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_IncomeStatementLocationAxis=us-gaap_InterestExpenseMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CrossCurrencyInterestRateContractMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_IncomeStatementLocationAxis=nav_OtherIncomeExpenseNetMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_IncomeStatementLocationAxis=us-gaap_CostOfSalesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |