| **Consolidated Statements of Stockholders’ Deficit Consolidated Statements of Stockholders' Deficit (Parenthetical) - USD ($) $ in Millions** | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Statement of Stockholders' Equity [Abstract]**                                                                                                    |            |   |
| Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Tax                                                                | $ 16            | $ 0 |
| Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Repurchase, Tax                                                    | $ 3             |   |

| X                                                                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Repurchase, Tax
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Tax
+ References
No definition available.
+ Details**Name:**nav_AdjustmentstoAdditionalPaidinCapitalEquityComponentofConvertibleDebtTax**Namespace Prefix:**nav_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - References
No definition available.
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