| **Property and Equipment, Net Narrative (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended                                           |
|----------------------------------------------------------------------------------------------------|-----------------------------------------------------------|
||
| **Property, Plant and Equipment [Line Items]**                                                     |                                                      |   |   |
| Commitments For Capital Expenditures In Progress                                                   | $ 15nav_CommitmentsForCapitalExpendituresInProgress       | $ 11nav_CommitmentsForCapitalExpendituresInProgress | $ 48nav_CommitmentsForCapitalExpendituresInProgress |
| Capital Expenditures Incurred but Not yet Paid                                                     | 1us-gaap_CapitalExpendituresIncurredButNotYetPaid         | 2us-gaap_CapitalExpendituresIncurredButNotYetPaid | 29us-gaap_CapitalExpendituresIncurredButNotYetPaid |
| Operating Leases, Rent Expense                                                                     | 62us-gaap_LeaseAndRentalExpense                           | 74us-gaap_LeaseAndRentalExpense | 63us-gaap_LeaseAndRentalExpense |
| Operating Leases, Income Statement, Sublease Revenue                                               | $ 10us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue | $ 7us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue | $ 4us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue |
| Minimum [Member]                                                                                   |                                                      |   |   |
| **Property, Plant and Equipment [Line Items]**                                                     |                                                      |   |   |
| Lessee Leasing Arrangements, Operating Leases, Term of Contract                                    | 1 year                                                    |   |   |
| Maximum [Member]                                                                                   |                                                      |   |   |
| **Property, Plant and Equipment [Line Items]**                                                     |                                                      |   |   |
| Lessee Leasing Arrangements, Operating Leases, Term of Contract                                    | 20 years                                                  |   |   |

| X                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Commitments For Capital Expenditures In Progress
+ References
No definition available.
+ Details**Name:**nav_CommitmentsForCapitalExpendituresInProgress**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Future cash outflow to pay for purchases of fixed assets that have occurred.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.
+ References
No definition available.
+ Details**Name:**us-gaap_LeaseAndRentalExpense**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Term of the lessee's leasing arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
+ References
No definition available.
+ Details**Name:**us-gaap_LesseeLeasingArrangementsOperatingLeasesTermOfContract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of revenue recognized for the period under subleasing arrangements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 55 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6584307&loc=d3e41620-112719
+ Details**Name:**us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_PropertyPlantAndEquipmentLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
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