| **Postretirement benefits (Tables)**                  | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|-------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Compensation and Retirement Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Components of Net Periodic Benefit Expense (Income)   | Net postretirement benefits expense (income) included in our Consolidated Statements of Operations is comprised of the following:  Three Months Ended April 30, Six Months Ended April 30, PensionBenefits Health andLife InsuranceBenefits PensionBenefits Health andLife InsuranceBenefits 2012 2011 2012 2011 2012 2011 2012 2011(in millions)               Service cost for benefits earned during the period$4 $5 $2 $2 $8 $9 $4 $4Interest on obligation43 47 21 14 86 94 42 27Amortization of cumulative loss27 25 11 — 55 50 20 —Amortization of prior service benefit— — (1) (7) — — (2) (15)Settlements and curtailments— — — — — 2 — —Contractual termination benefits— — — — — 3 (3) —Premiums on pension insurance1 1 — — 1 1 — —Expected return on assets(48) (53) (9) (11) (96) (105) (18) (21)Net postretirement benefits expense (income)$27 $25 $24 $(2) $54 $54 $43 $(5) |

| X                                                                                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Components Of Postretirement Benefits Income Expense Included in Statement Of Operations [Table Text Block]
+ References
No definition available.
+ Details**Name:**nav_ComponentsOfPostretirementBenefitsIncomeExpenseIncludedInStatementOfOperationsTableTextBlock**Namespace Prefix:**nav_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CompensationAndRetirementDisclosureAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |