| **Segment Reporting - Summary of Segment Long Lived Assets and Revenue (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended                                                                          | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------|-----------------|
||
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           | $ 3,008us-gaap_Revenues                                                                 |                 | $ 2,844us-gaap_Revenues | $ 2,746us-gaap_Revenues | $ 2,208us-gaap_Revenues | $ 2,751us-gaap_Revenues |  | $ 2,861us-gaap_Revenues | $ 2,526us-gaap_Revenues | $ 2,637us-gaap_Revenues | $ 10,806us-gaap_Revenues |  | $ 10,775us-gaap_Revenues |  | $ 12,695us-gaap_Revenues |
| UNITED STATES                                                                                                                     |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 7,760us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_US |  | 7,122us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_US |  | 8,822us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_US |
| Long-Lived Assets                                                                                                                 | 1,277us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_US            | [1]             |   |   |   | 1,467us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_US | [1] |   |   |   | 1,277us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_US | [1] | 1,467us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_US | [1] |   |
| CANADA                                                                                                                            |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 749us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_CA |  | 791us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_CA |  | 949us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_CA |
| Long-Lived Assets                                                                                                                 | 26us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_CA               | [1]             |   |   |   | 26us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_CA | [1] |   |   |   | 26us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_CA | [1] | 26us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_CA | [1] |   |
| MEXICO                                                                                                                            |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 657us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_MX |  | 694us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_MX |  | 728us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_MX |
| Long-Lived Assets                                                                                                                 | 190us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_MX              | [1]             |   |   |   | 157us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_MX | [1] |   |   |   | 190us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_MX | [1] | 157us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_MX | [1] |   |
| BRAZIL                                                                                                                            |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 833us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_BR |  | 1,121us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_BR |  | 1,066us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= country_BR |
| Long-Lived Assets                                                                                                                 | 182us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_BR              | [1]             |   |   |   | 376us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_BR | [1] |   |   |   | 182us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_BR | [1] | 376us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= country_BR | [1] |   |
| Other Countries [Member]                                                                                                          |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 807us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= nav_OtherCountriesMember |  | 1,047us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= nav_OtherCountriesMember |  | 1,130us-gaap_Revenues/ us-gaap_StatementGeographicalAxis= nav_OtherCountriesMember |
| Long-Lived Assets                                                                                                                 | 15us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= nav_OtherCountriesMember | [1]             |   |   |   | 37us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= nav_OtherCountriesMember | [1] |   |   |   | 15us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= nav_OtherCountriesMember | [1] | 37us-gaap_NoncurrentAssets/ us-gaap_StatementGeographicalAxis= nav_OtherCountriesMember | [1] |   |
| Truck [Member]                                                                                                                    |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 7,137us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_TruckMember |  | 6,738us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_TruckMember |  | 8,705us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_TruckMember |
| Parts [Member]                                                                                                                    |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 2,424us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_PartsMember |  | 2,906us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_PartsMember |  | 2,886us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_PartsMember |
| Engine [Member]                                                                                                                   |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | 1,092us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_EngineMember |  | 973us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_EngineMember |  | 936us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_EngineMember |
| Financial Services Operations [Member]                                                                                            |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| **Revenues from External Customers and Long-Lived Assets [Line Items]**                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   |   |  |   |  |   |
| Sales and revenues, net                                                                                                           |                                                                                    |                 |   |   |   |   |  |   |   |   | $ 153us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_FinancialServicesOperationsMember |  | $ 158us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_FinancialServicesOperationsMember |  | $ 168us-gaap_Revenues/ us-gaap_ProductOrServiceAxis= nav_FinancialServicesOperationsMember |
|                                                                                                                                   |
| [1]Long-lived assets consist of Property and equipment, net, Goodwill, and Intangible assets, net.                                |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 41 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599
+ Details**Name:**us-gaap_NoncurrentAssets**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 5
+ Details**Name:**us-gaap_Revenues**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_ProductOrServiceAxis=nav_EngineMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_ProductOrServiceAxis=nav_FinancialServicesOperationsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_ProductOrServiceAxis=nav_PartsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_ProductOrServiceAxis=nav_TruckMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=country_BR**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=country_CA**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=country_MX**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=country_US**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=nav_OtherCountriesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |