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Summary of Significant Accounting Policies - Identified Intangible Assets Identified by Segment (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Intangible Asset Excluding Goodwill [Line Items]
Beginning Balance	$ 5,055us-gaap_IntangibleAssetsNetExcludingGoodwill	$ 4,743us-gaap_IntangibleAssetsNetExcludingGoodwill
Additions to intangible assets	59nov_IntangibleAssetsAcquiredDuringPeriod	696nov_IntangibleAssetsAcquiredDuringPeriod
Disposal of intangible assets	(117)us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssets
Asset impairment	(104)us-gaap_AssetImpairmentCharges
Amortization	(366)us-gaap_AmortizationOfIntangibleAssets	(363)us-gaap_AmortizationOfIntangibleAssets
Currency translation adjustments and other	(83)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments	(21)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments
Ending Balance	4,444us-gaap_IntangibleAssetsNetExcludingGoodwill	5,055us-gaap_IntangibleAssetsNetExcludingGoodwill
Discontinued Operations [Member]
Intangible Asset Excluding Goodwill [Line Items]
Beginning Balance	68us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentDiscontinuedOperationsMember	74us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentDiscontinuedOperationsMember
Disposal of intangible assets	(67)us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentDiscontinuedOperationsMember
Amortization	(1)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentDiscontinuedOperationsMember	(6)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentDiscontinuedOperationsMember
Ending Balance		68us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentDiscontinuedOperationsMember
Rig Systems [Member]
Intangible Asset Excluding Goodwill [Line Items]
Beginning Balance	232us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember	62us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember
Additions to intangible assets		190nov_IntangibleAssetsAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember
Amortization	(22)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember	(21)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember
Currency translation adjustments and other	(2)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember	1nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember
Ending Balance	208us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember	232us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigSystemsMember
Rig Aftermarket [Member]
Intangible Asset Excluding Goodwill [Line Items]
Beginning Balance	142us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember	89us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember
Additions to intangible assets		59nov_IntangibleAssetsAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember
Amortization	(6)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember	(6)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember
Currency translation adjustments and other	(3)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember
Ending Balance	133us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember	142us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_RigAfterMarketMember
Wellbore Technologies [Member]
Intangible Asset Excluding Goodwill [Line Items]
Beginning Balance	2,999us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember	2,942us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember
Additions to intangible assets	5nov_IntangibleAssetsAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember	286nov_IntangibleAssetsAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember
Asset impairment	(104)us-gaap_AssetImpairmentCharges / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember
Amortization	(218)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember	(217)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember
Currency translation adjustments and other	(16)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember	(12)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember
Ending Balance	2,666us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember	2,999us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_WellboreTechnologiesMember
Completion & Production Solutions [Member]
Intangible Asset Excluding Goodwill [Line Items]
Beginning Balance	1,614us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember	1,576us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember
Additions to intangible assets	54nov_IntangibleAssetsAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember	161nov_IntangibleAssetsAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember
Disposal of intangible assets	(50)us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember
Amortization	(119)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember	(113)us-gaap_AmortizationOfIntangibleAssets / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember
Currency translation adjustments and other	(62)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember	(10)nov_IntangibleAssetsTranslationAndPurchaseAccountingAdjustments / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember
Ending Balance	$ 1,437us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember	$ 1,614us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_StatementBusinessSegmentsAxis = nov_CompletionAndProductionSolutionsMember

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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