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Employee Benefit Plans - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Employees
Dec. 31, 2013
Dec. 31, 2012
Compensation Related Costs Disclosure [Line Items]      
Expenses for defined-contribution plans $ 115us-gaap_DefinedContributionPlanCostRecognized $ 96us-gaap_DefinedContributionPlanCostRecognized $ 82us-gaap_DefinedContributionPlanCostRecognized
Number of U.S retirees and spouses participate in defined benefit health care plans 1,081nov_DefinedBenefitPlanNumberOfUnitedStatesRetireesAndSpousesParticipateInDefinedBenefitHealthCarePlans    
Net periodic benefit cost 7us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost 10us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost 10us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Defined benefit plan, expected future benefit payments in year five 41us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive    
Expected years of defined benefit plans 5 years    
Expected future benefit amounts to pay, total $ 420nov_DefinedBenefitPlanEstimatedFutureEmployerContributions    
Robbins and Myers [Member]      
Compensation Related Costs Disclosure [Line Items]      
Number of defined benefit pension plans acquired 4nov_NumberOfDefinedBenefitPensionPlans
/ us-gaap_BusinessAcquisitionAxis
= nov_RobbinsAndMyersMember		    
Number of U.S. employees participate in defined benefit health care plans 230nov_DefinedBenefitPlanNumberOfEmployeesParticipateInDefinedBenefitHealthCarePlans
/ us-gaap_BusinessAcquisitionAxis
= nov_RobbinsAndMyersMember		    
Number of retirees and dependents covered in defined benefit health care plans 400nov_DefinedBenefitPlanNumberOfUnitedStatesRetiredEmployeesAndDependentsCoveredInDefinedBenefitHealthCarePlans
/ us-gaap_BusinessAcquisitionAxis
= nov_RobbinsAndMyersMember		    
Robbins and Myers [Member] | Pension Benefits [Member]      
Compensation Related Costs Disclosure [Line Items]      
Number of defined benefit pension plans acquired 2nov_NumberOfDefinedBenefitPensionPlans
/ us-gaap_BusinessAcquisitionAxis
= nov_RobbinsAndMyersMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		    
Robbins and Myers [Member] | Contributory Pension Benefits [Member]      
Compensation Related Costs Disclosure [Line Items]      
Number of defined benefit pension plans acquired 1nov_NumberOfDefinedBenefitPensionPlans
/ us-gaap_BusinessAcquisitionAxis
= nov_RobbinsAndMyersMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= nov_ContributoryPensionBenefitsMember