| **Investments in Non-Consolidated Affiliates Combined Results of Operations of Equity Method Investments (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended                                                                                   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------|
||
| **Investments in and Advances to Affiliates, Schedule of Investments [Abstract]**                                                                                   |                                                                                              |   |   |
| Equity Method Investment, Summarized Financial Information, Revenue                                                                                                 | $ 527us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue                          | $ 448us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue | $ 704us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue |
| Equity Method Investment, Summarized Financial Information, Cost of Sales, Expenses and Income Tax Expense                                                          | 500nav_EquityMethodInvestmentSummarizedFinancialInformationCostOfSalesExpensesAndIncomeTaxExpense | 412nav_EquityMethodInvestmentSummarizedFinancialInformationCostOfSalesExpensesAndIncomeTaxExpense | 726nav_EquityMethodInvestmentSummarizedFinancialInformationCostOfSalesExpensesAndIncomeTaxExpense |
| Equity Method Investment, Summarized Financial Information, Net Income (Loss)                                                                                       | $ 27us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss                     | $ 36us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss | $ (22)us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss |

| X                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Equity Method Investment, Summarized Financial Information, Cost of Sales, Expenses and Income Tax Expense
+ References
No definition available.
+ Details**Name:**nav_EquityMethodInvestmentSummarizedFinancialInformationCostOfSalesExpensesAndIncomeTaxExpense**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of net income (loss) reported by an equity method investment of the entity.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(g)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33912-111571Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph bb -Article 1Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph g -Subparagraph 1, 2 -Article 4Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph w -Article 1
+ Details**Name:**us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.
+ References
No definition available.
+ Details**Name:**us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_InvestmentsInAndAdvancesToAffiliatesScheduleOfInvestmentsAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |