| **Financial Instruments and Commodity Contracts - Derivative Financial Instruments (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended                                                                                                                                                                                          | 6 Months Ended                                                                                                                                                                                            |
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| **Derivative [Line Items]**                                                                                                                   |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                                             | $ (4)us-gaap_DerivativeGainLossOnDerivativeNet                                                                                                                                                          | $ 2us-gaap_DerivativeGainLossOnDerivativeNet                                                                                                                                                              | $ 9us-gaap_DerivativeGainLossOnDerivativeNet | $ 2us-gaap_DerivativeGainLossOnDerivativeNet |
| Interest Rate Cap [Member] | Interest Expense [Member]                                                                                        |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| **Derivative [Line Items]**                                                                                                                   |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                                             | 0us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_InterestExpenseMember                     | (2)us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_InterestExpenseMember                     | 0us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_InterestExpenseMember | (1)us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_InterestExpenseMember |
| Cross currency swaps | Other Income Expense Net [Member]                                                                                      |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| **Derivative [Line Items]**                                                                                                                   |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                                             | 1us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CrossCurrencyInterestRateContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember | (1)us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CrossCurrencyInterestRateContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember | 3us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CrossCurrencyInterestRateContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember | 1us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CrossCurrencyInterestRateContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember |
| Foreign Exchange Contract [Member] | Other Income Expense Net [Member]                                                                        |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| **Derivative [Line Items]**                                                                                                                   |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                                             | 0us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember           | 1us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember             | 1us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember | 0us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_IncomeStatementLocationAxis= nav_OtherIncomeExpenseNetMember |
| Commodity Contract [Member] | Cost of Sales [Member]                                                                                          |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| **Derivative [Line Items]**                                                                                                                   |                                                                                                                                                                                                    |                                                                                                                                                                                                      |   |   |
| Derivative Instruments,Derivative, Gain (Loss) on Derivative, Net                                                                             | $ 5us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CommodityContractMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_CostOfSalesMember                     | $ 0us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CommodityContractMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_CostOfSalesMember                       | $ (5)us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CommodityContractMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_CostOfSalesMember | $ 0us-gaap_DerivativeGainLossOnDerivativeNet/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_CommodityContractMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_CostOfSalesMember |

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| - 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
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