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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
Share data in Millions, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Indefinite-lived Intangible Assets [Line Items]        
Maturity period of investments description   Three months or less    
Minimum derivative financial instrument's term (months)   2 months    
Maximum derivative financial instrument's term (months)   24 months    
Allowances for excess and obsolete inventories   $ 370,000,000us-gaap_InventoryAdjustments $ 396,000,000us-gaap_InventoryAdjustments  
Depreciation expense related to property, plant and equipment   413,000,000us-gaap_Depreciation 381,000,000us-gaap_Depreciation 315,000,000us-gaap_Depreciation
Impairment of long-lived assets   0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse 0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse 0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Goodwill   8,539,000,000us-gaap_Goodwill 9,049,000,000us-gaap_Goodwill 7,172,000,000us-gaap_Goodwill
Indefinite-lived intangible assets   4,444,000,000us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill 5,055,000,000us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill  
Estimated useful lives of intangible assets, minimum   2 years    
Estimated useful lives of intangible assets, maximum   30 years    
Amortization expense   340,000,000nov_FiniteLivedIntangibleAssetsAmortizationExpenses    
Number of years as first period of amortization   5 years    
Intangible asset impairment   104,000,000us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill    
Net foreign currency transaction gains (losses)   20,000,000us-gaap_ForeignCurrencyTransactionGainLossRealized (24,000,000)us-gaap_ForeignCurrencyTransactionGainLossRealized (18,000,000)us-gaap_ForeignCurrencyTransactionGainLossRealized
Net investment in Venezuela   45,000,000nov_NetInvestments    
Devaluation charges 12,000,000nov_DevaluedAssetCharges      
Net allowances for doubtful accounts   125,000,000us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent 132,000,000us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent  
Compensation cost charged against income for share-based compensation arrangements   101,000,000us-gaap_AllocatedShareBasedCompensationExpense 92,000,000us-gaap_AllocatedShareBasedCompensationExpense 80,000,000us-gaap_AllocatedShareBasedCompensationExpense
Income tax benefit recognized for share-based compensation arrangements   35,000,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 28,000,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 24,000,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Anti-dilutive stock options outstanding   8us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount 7us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount 5us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Wellbore Technologies [Member]        
Indefinite-lived Intangible Assets [Line Items]        
Goodwill   4,357,000,000us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= nov_WellboreTechnologiesMember		 4,425,000,000us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= nov_WellboreTechnologiesMember		 3,769,000,000us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= nov_WellboreTechnologiesMember
Indefinite-lived Trade Names [Member]        
Indefinite-lived Intangible Assets [Line Items]        
Indefinite-lived intangible assets   540,000,000us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeNamesMember		    
Other Intangible Assets [Member] | Wellbore Technologies [Member]        
Indefinite-lived Intangible Assets [Line Items]        
Intangible asset impairment   $ 104,000,000us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_OtherIntangibleAssetsMember
/ us-gaap_StatementBusinessSegmentsAxis
= nov_WellboreTechnologiesMember