Name:	nov_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFinanceAndOperatingLeaseLiabilities
Namespace Prefix:	nov_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Business combination recognized identifiable assets acquired and liabilities assumed finance and other liabilities.

No definition available.

Name:	nov_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFinanceAndOtherLiabilities
Namespace Prefix:	nov_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Business combination, recognized identifiable assets acquired and liabilities assumed, intangible assets, including goodwill.

No definition available.

Name:	nov_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsIncludingGoodwill
Namespace Prefix:	nov_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Business combination, recognized identifiable assets acquired and liabilities assumed, working capital.

No definition available.

Name:	nov_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedWorkingCapital
Namespace Prefix:	nov_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Business combination recognized identifiable gain.

No definition available.

Name:	nov_BusinessCombinationRecognizedIdentifiableGain
Namespace Prefix:	nov_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-5

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

The amount of property, plant, and equipment recognized as of the acquisition date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-37

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The number of businesses acquired by the entity during the period.

No definition available.

Name:	us-gaap_NumberOfBusinessesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The cash outflow associated with the purchase of noncontrolling interest during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-13

Name:	us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.