| **Commitments and Contingencies - Narrative (Details)**                                                           | 6 Months Ended                                                  | 1 Months Ended                                                                                                                                                                                                             | 3 Months Ended                                                                                                                                                                                                             | 1 Months Ended                                                                                                                                                                                                                     | 3 Months Ended                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                     | 3 Months Ended                                                                                                                         | 12 Months Ended                                                                                                               | 6 Months Ended                                                                                                              |                                                                                                                                       | 6 Months Ended                                                                                                                        |                                                                                                                                                     |                                                                                                                                                     |                                                                                                                                                                      | 6 Months Ended                                                                                                                                                              | 3 Months Ended                                                                                                                                                              |                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Loss Contingencies [Line Items]**                                                                               |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Operating Agreement Excess Loss Percentage                                                                        |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        | 10.00%nav_OperatingAgreementExcessLossPercentage/ us-gaap_TypeOfArrangementAxis= nav_GEOperatingAgreementMember                       |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Loss Sharing Agreement, Percentage                                                                                |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        | 9.50%nav_LossSharingAgreementPercentage/ us-gaap_TypeOfArrangementAxis= nav_GEOperatingAgreementMember                                |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Off Balance Sheet Finance Receivables                                                                             |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        | $ 1,600,000,000nav_OffBalanceSheetFinanceReceivables/ us-gaap_TypeOfArrangementAxis= nav_GEOperatingAgreementMember                   | $ 1,500,000,000nav_OffBalanceSheetFinanceReceivables/ us-gaap_TypeOfArrangementAxis= nav_GEOperatingAgreementMember                   |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Off Balance Sheet Finance Receivables Related Originations                                                        |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        | 2,300,000,000nav_OffBalanceSheetFinanceReceivablesRelatedOriginations1/ us-gaap_TypeOfArrangementAxis= nav_GEOperatingAgreementMember | 2,300,000,000nav_OffBalanceSheetFinanceReceivablesRelatedOriginations1/ us-gaap_TypeOfArrangementAxis= nav_GEOperatingAgreementMember |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Equipment leased to others                                                                                        |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                | 129,000,000nav_Equipmentleasedtoothers/ us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis= nav_GEOperatingAgreementMember |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Long-term Debt                                                                                                    |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 | 141,000,000us-gaap_LongTermDebt/ us-gaap_LongtermDebtTypeAxis= nav_FinancedLeaseObligationsMember/ us-gaap_StatementBusinessSegmentsAxis= nav_ManufacturingOperationsMember | 184,000,000us-gaap_LongTermDebt/ us-gaap_LongtermDebtTypeAxis= nav_FinancedLeaseObligationsMember/ us-gaap_StatementBusinessSegmentsAxis= nav_ManufacturingOperationsMember | 139,000,000us-gaap_LongTermDebt/ us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis= nav_GEOperatingAgreementMember/ us-gaap_LongtermDebtTypeAxis= nav_FinancedLeaseObligationsMember/ us-gaap_StatementBusinessSegmentsAxis= nav_ManufacturingOperationsMember |   |   |   |   |   |   |   |
| Historical losses on finance receivables, measured as percentage of average balance of related finance receivable |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  | 0.30%nav_HistoricLossesOnFinanceReceivablesMeasuredAsPercentageOfAverageBalanceOfRelatedFinanceReceivable/ us-gaap_RangeAxis= us-gaap_MinimumMember | 2.10%nav_HistoricLossesOnFinanceReceivablesMeasuredAsPercentageOfAverageBalanceOfRelatedFinanceReceivable/ us-gaap_RangeAxis= us-gaap_MaximumMember |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Available stand-by letters of credit and surety bonds                                                             | 88,000,000us-gaap_LettersOfCreditOutstandingAmount              |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Line of Credit Facility, Current Borrowing Capacity                                                               | 11,000,000us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity  |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Line of Credit Facility, Remaining Borrowing Capacity                                                             | 7,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Purchase commitments                                                                                              | 120,000,000us-gaap_PurchaseObligation                           |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Long Term Purchase Commitment Cancellation Fees                                                                   | 33,000,000nav_LongTermPurchaseCommitmentCancellationFees        |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Number of Contaminated Sites                                                                                      | 2nav_NumberOfContaminatedSites                                  |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Number of Contaminated Sites in Sao Paulo, Brazil                                                                 | 2nav_NumberOfContaminatedSitesInSaoPauloBrazil                  |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Accrual for environmental loss contingencies                                                                      | 22,000,000us-gaap_AccrualForEnvironmentalLossContingencies      |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Damages sought, value                                                                                             |                                                            | 3,000,000us-gaap_LossContingencyDamagesSoughtValue/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= nav_SaoPauloGroundwaterNoticeMember/ nav_LossContingencyByTypeOfPossibleLossAxis= nav_SanctionsMember | 1,000,000us-gaap_LossContingencyDamagesSoughtValue/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= nav_SaoPauloGroundwaterNoticeMember/ nav_LossContingencyByTypeOfPossibleLossAxis= nav_SanctionsMember |                                                                                                                                                                                                                               | 64,000,000us-gaap_LossContingencyDamagesSoughtValue/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= nav_InternationalChamberofCommerceMember/ nav_LossContingencyByTypeOfPossibleLossAxis= nav_PenaltiesandInterestMember | 128,000,000us-gaap_LossContingencyDamagesSoughtValue/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= nav_NavitrucksMember/ nav_LossContingencyByTypeOfPossibleLossAxis= nav_AllegedUnfulfilledPromisesandInjurytoReputationMember |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      | 50,000,000us-gaap_LossContingencyDamagesSoughtValue/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= us-gaap_DisputesMember/ us-gaap_LitigationStatusAxis= us-gaap_PendingLitigationMember | 1,000,000us-gaap_LossContingencyDamagesSoughtValue/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= nav_FatmaNoticeTrialMember/ us-gaap_LitigationStatusAxis= us-gaap_PendingLitigationMember/ nav_LossContingencyByTypeOfPossibleLossAxis= nav_PenaltiesMember | 2,000,000us-gaap_LossContingencyDamagesSoughtValue/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= nav_FatmaNoticeTrialMember/ us-gaap_LitigationStatusAxis= us-gaap_PendingLitigationMember/ nav_LossContingencyByTypeOfPossibleLossAxis= nav_PenaltiesMember |   |   |   |   |
| Loss Contingency, Number of Plaintiffs                                                                            |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       | 4us-gaap_LossContingencyNumberOfPlaintiffs/ nav_ContingencyDisclosureRelatedToLitigationByTrialOrRulingAxis= nav_InternationalChamberofCommerceMember/ nav_LossContingencyByTypeOfPossibleLossAxis= nav_PenaltiesandInterestMember |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Notice of Violation, number                                                                                       |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                | 7,600nav_NoticeOfViolationNumberOfEngines/ us-gaap_LossContingenciesByNatureOfContingencyAxis= us-gaap_DamagesFromProductDefectsMember |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Regulatory Penalty                                                                                                |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   | 2,500,000nav_RegulatoryPenalty/ us-gaap_LossContingenciesByNatureOfContingencyAxis= nav_CaliforniaAirResourcesBoardCarbMember | 300,000nav_RegulatoryPenalty/ us-gaap_LossContingenciesByNatureOfContingencyAxis= nav_CaliforniaAirResourcesBoardCarbMember |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |   |   |
| Gain Contingency, Unrecorded Amount                                                                               |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   | 24,000,000us-gaap_GainContingencyUnrecordedAmount/ us-gaap_LitigationCaseAxis= nav_IIAAVs.NavitrucksMember | 71,000,000us-gaap_GainContingencyUnrecordedAmount/ us-gaap_LitigationCaseAxis= nav_IIAAVs.NavitrucksMember |   |   |
| Loss Contingency, Estimate of Possible Loss                                                                       |                                                            |                                                                                                                                                                                                                       |                                                                                                                                                                                                                       |                                                                                                                                                                                                                               |                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                |                                                                                                                                   |                                                                                                                          |                                                                                                                        |                                                                                                                                  |                                                                                                                                  |                                                                                                                                                |                                                                                                                                                |                                                                                                                                                                 |                                                                                                                                                                        |                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                      |   |   |   |   |   | $ 61,000,000us-gaap_LossContingencyEstimateOfPossibleLoss/ us-gaap_LitigationCaseAxis= nav_NavitrucksVs.IIAAMember | 182,000,000us-gaap_LossContingencyEstimateOfPossibleLoss/ us-gaap_LitigationCaseAxis= nav_NavitrucksVs.IIAAMember |

| X                                                                                                                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Equipment leased to others
+ References
No definition available.
+ Details**Name:**nav_Equipmentleasedtoothers**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                             |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Historic Losses On Finance Receivables Measured As Percentage Of Average Balance Of Related Finance Receivable
+ References
No definition available.
+ Details**Name:**nav_HistoricLossesOnFinanceReceivablesMeasuredAsPercentageOfAverageBalanceOfRelatedFinanceReceivable**Namespace Prefix:**nav_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Long Term Purchase Commitment Cancellation Fees
+ References
No definition available.
+ Details**Name:**nav_LongTermPurchaseCommitmentCancellationFees**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Loss Sharing Agreement, Percentage
+ References
No definition available.
+ Details**Name:**nav_LossSharingAgreementPercentage**Namespace Prefix:**nav_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Notice of Violation, number of engines
+ References
No definition available.
+ Details**Name:**nav_NoticeOfViolationNumberOfEngines**Namespace Prefix:**nav_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of Contaminated Sites
+ References
No definition available.
+ Details**Name:**nav_NumberOfContaminatedSites**Namespace Prefix:**nav_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of Contaminated Sites in Sao Paulo, Brazil
+ References
No definition available.
+ Details**Name:**nav_NumberOfContaminatedSitesInSaoPauloBrazil**Namespace Prefix:**nav_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Off Balance Sheet Finance Receivables1
+ References
No definition available.
+ Details**Name:**nav_OffBalanceSheetFinanceReceivables**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Off Balance Sheet Finance Receivables Related Originations1
+ References
No definition available.
+ Details**Name:**nav_OffBalanceSheetFinanceReceivablesRelatedOriginations1**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Operating Agreement Excess Loss Percentage
+ References
No definition available.
+ Details**Name:**nav_OperatingAgreementExcessLossPercentage**Namespace Prefix:**nav_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Regulatory Penalty
+ References
No definition available.
+ Details**Name:**nav_RegulatoryPenalty**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Total costs accrued as of the balance sheet date for environmental loss contingencies.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346
+ Details**Name:**us-gaap_AccrualForEnvironmentalLossContingencies**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355
+ Details**Name:**us-gaap_GainContingencyUnrecordedAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.
+ References
No definition available.
+ Details**Name:**us-gaap_LettersOfCreditOutstandingAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5
+ Details**Name:**us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5
+ Details**Name:**us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910
+ Details**Name:**us-gaap_LongTermDebt**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LossContingenciesLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The value (monetary amount) of the award the plaintiff seeks in the legal matter.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349
+ Details**Name:**us-gaap_LossContingencyDamagesSoughtValue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349
+ Details**Name:**us-gaap_LossContingencyEstimateOfPossibleLoss**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of plaintiffs that have filed claims pertaining to a loss contingency.
+ References
No definition available.
+ Details**Name:**us-gaap_LossContingencyNumberOfPlaintiffs**Namespace Prefix:**us-gaap_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.
+ References
No definition available.
+ Details**Name:**us-gaap_PurchaseObligation**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |