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Accumulated Other Comprehensive Loss - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2021
Statement Of Income And Comprehensive Income [Abstract] |  |
Changes in fair value of open derivatives | $ (4) | $ (7)
Cumulative changes in the fair value of derivatives | $ (2) | $ (5)

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- Definition Change in fair value of derivative. + References No definition available. + Details
Name: | nov_ChangeInFairValueOfDerivative
Namespace Prefix: | nov_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Other comprehensive income (loss), cumulative change in net gain (loss) from cash flow hedges, tax. + References No definition available. + Details
Name: | nov_OtherComprehensiveIncomeLossCumulativeChangeInNetGainLossFromCashFlowHedgesTax
Namespace Prefix: | nov_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration