| **Restructuring and Impairments - Narrative (Details) (USD $)In Millions, unless otherwise specified**                                                 | 12 Months Ended                                                                                                                                                                                                                      | 3 Months Ended                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------|
||
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  | $ 42us-gaap_RestructuringCharges                                                                                                                                                                                                     | $ 25us-gaap_RestructuringCharges                                                                      | $ 107us-gaap_RestructuringCharges |   |   |   |   |   |   |   |   |
| Asset impairment charges                                                                                                                               | 183us-gaap_AssetImpairmentCharges                                                                                                                                                                                                    | 97us-gaap_AssetImpairmentCharges                                                                      | 16us-gaap_AssetImpairmentCharges |   |   |   |   |   |   |   |   |
| Employee Severance [Member]                                                                                                                            |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   | 8us-gaap_RestructuringCharges/ us-gaap_RestructuringCostAndReserveAxis= us-gaap_EmployeeSeveranceMember | 11us-gaap_RestructuringCharges/ us-gaap_RestructuringCostAndReserveAxis= us-gaap_EmployeeSeveranceMember |   |   |   |   |   |   |
| North America Truck [Member]                                                                                                                           |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Asset impairment charges                                                                                                                               | 19us-gaap_AssetImpairmentCharges/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Warrenville [Member] | North America Truck [Member] | Lease Vacancy [Member] [Domain]                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   | 16us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_WarrenvilleMember/ us-gaap_RestructuringCostAndReserveAxis= nav_LeaseVacancyMemberDomain/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |   |   |   |   |   |
| Warrenville [Member] | North America Truck [Member] | Lease Vacancy Fair Value [Member]                                                                |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   | 19us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_WarrenvilleMember/ us-gaap_RestructuringCostAndReserveAxis= nav_LeaseVacancyFairValueMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |   |   |   |   |   |
| Warrenville [Member] | North America Truck [Member] | Accrued Rent Expense, Reversal [Domain]                                                          |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   | 3us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_WarrenvilleMember/ us-gaap_RestructuringCostAndReserveAxis= nav_AccruedRentExpenseReversalDomain/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |   |   |   |   |   |
| Chatham [Member] | North America Truck [Member]                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   | 14us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_ChathamMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |   |   |   |   |
| Garland Assembly Plant [Member] | North America Truck [Member] | Garland plant closure [Member]                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   | 8us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_GarlandAssemblyPlantMember/ us-gaap_RestructuringCostAndReserveAxis= nav_GarlandPlantClosureMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember | 12us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_GarlandAssemblyPlantMember/ us-gaap_RestructuringCostAndReserveAxis= nav_GarlandPlantClosureMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |   |   |
| Huntsville Engine Plant [Member] | North America Truck [Member] | Employee Severance [Member]                                                          |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   | 1us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_HuntsvilleEnginePlantMember/ us-gaap_RestructuringCostAndReserveAxis= us-gaap_EmployeeSeveranceMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |   |
| Huntsville Engine Plant [Member] | North America Truck [Member] | Engine Plant Consolidation [Member]                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   | 2us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_HuntsvilleEnginePlantMember/ us-gaap_RestructuringCostAndReserveAxis= nav_EnginePlantConsolidationMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |   |
| Indianapolis and Waukesha Foundry [Member] | North America Truck [Member]                                                                              |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   | 13us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_IndianapolisandWaukeshaFoundryMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Asset impairment charges                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   | 7us-gaap_AssetImpairmentCharges/ dei_EntityByLocationAxis= nav_IndianapolisandWaukeshaFoundryMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Indianapolis and Waukesha Foundry [Member] | North America Truck [Member] | Employee Severance [Member]                                                |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   | 2us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_IndianapolisandWaukeshaFoundryMember/ us-gaap_RestructuringCostAndReserveAxis= us-gaap_EmployeeSeveranceMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Indianapolis and Waukesha Foundry [Member] | North America Truck [Member] | Pension And Other Postretirement Contractual Termination Benefits [Member] |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   | 11us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_IndianapolisandWaukeshaFoundryMember/ us-gaap_RestructuringCostAndReserveAxis= nav_PensionAndOtherPostretirementContractualTerminationBenefitsMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Indianapolis and Waukesha Foundry [Member] | North America Truck [Member] | Restructuring Inventory Adjustments [Member]                               |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring charges                                                                                                                                  |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   | 7us-gaap_RestructuringCharges/ dei_EntityByLocationAxis= nav_IndianapolisandWaukeshaFoundryMember/ us-gaap_RestructuringCostAndReserveAxis= nav_RestructuringInventoryAdjustmentsMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Minimum [Member] | Chatham [Member] | North America Truck [Member]                                                                                     |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring and Related Cost, Expected Cost                                                                                                          | 0us-gaap_RestructuringAndRelatedCostExpectedCost1/ dei_EntityByLocationAxis= nav_ChathamMember/ us-gaap_RangeAxis= us-gaap_MinimumMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember                         |                                                                                                  |   |   |   |   |   |   |   |   | 0us-gaap_RestructuringAndRelatedCostExpectedCost1/ dei_EntityByLocationAxis= nav_ChathamMember/ us-gaap_RangeAxis= us-gaap_MinimumMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Maximum [Member] | Chatham [Member] | North America Truck [Member]                                                                                     |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring and Related Cost, Expected Cost                                                                                                          | 60us-gaap_RestructuringAndRelatedCostExpectedCost1/ dei_EntityByLocationAxis= nav_ChathamMember/ us-gaap_RangeAxis= us-gaap_MaximumMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember                        |                                                                                                  |   |   |   |   |   |   |   |   | 60us-gaap_RestructuringAndRelatedCostExpectedCost1/ dei_EntityByLocationAxis= nav_ChathamMember/ us-gaap_RangeAxis= us-gaap_MaximumMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Maximum [Member] | Indianapolis and Waukesha Foundry [Member] | North America Truck [Member]                                                           |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Restructuring and Related Cost, Expected Cost                                                                                                          | 40us-gaap_RestructuringAndRelatedCostExpectedCost1/ dei_EntityByLocationAxis= nav_IndianapolisandWaukeshaFoundryMember/ us-gaap_RangeAxis= us-gaap_MaximumMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |                                                                                                  |   |   |   |   |   |   |   |   | 40us-gaap_RestructuringAndRelatedCostExpectedCost1/ dei_EntityByLocationAxis= nav_IndianapolisandWaukeshaFoundryMember/ us-gaap_RangeAxis= us-gaap_MaximumMember/ us-gaap_StatementBusinessSegmentsAxis= nav_NorthAmericaTruckMember |
| Discontinuation Engineering Program [Member]                                                                                                           |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Asset impairment charges                                                                                                                               |                                                                                                                                                                                                                                 | 19us-gaap_AssetImpairmentCharges/ nav_ImpairmentTypeAxis= nav_DiscontinuationEngineeringProgramMember |   |   |   |   |   |   |   |   |   |
| Discontinued Operations [Member]                                                                                                                       |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                                                        |                                                                                                                                                                                                                                 |                                                                                                  |   |   |   |   |   |   |   |   |   |
| Asset impairment charges                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                  | $ 38us-gaap_AssetImpairmentCharges/ nav_ImpairmentTypeAxis= us-gaap_SegmentDiscontinuedOperationsMember |   |   |   |   |   |   |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount expected to be recognized in earnings for the specified restructuring cost.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.
+ References
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