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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)

X

- 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

X

- 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

X

- References

No definition available.

+ Details

Name:	us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration