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Summary of Significant Accounting Policies - Identified Intangible Assets by Major Classification (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Intangible Assets Net Excluding Goodwill [Line Items]
Gross	$ 6,559nov_IntangibleAssetsGross	$ 6,804nov_IntangibleAssetsGross
Accumulated Amortization	(2,115)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization	(1,749)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Net Book Value	4,444us-gaap_IntangibleAssetsNetExcludingGoodwill	5,055us-gaap_IntangibleAssetsNetExcludingGoodwill	4,743us-gaap_IntangibleAssetsNetExcludingGoodwill
Indefinite-lived Trade Names [Member]
Intangible Assets Net Excluding Goodwill [Line Items]
Gross	536nov_IntangibleAssetsGross / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TradeNamesMember	643nov_IntangibleAssetsGross / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TradeNamesMember
Net Book Value	536us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TradeNamesMember	643us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TradeNamesMember
Customer relationships [Member]
Intangible Assets Net Excluding Goodwill [Line Items]
Gross	4,094nov_IntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember	4,093nov_IntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Accumulated Amortization	(1,379)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember	(1,147)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Net Book Value	2,715us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember	2,946us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Trademarks [Member]
Intangible Assets Net Excluding Goodwill [Line Items]
Gross	871nov_IntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember	893nov_IntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember
Accumulated Amortization	(226)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember	(195)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember
Net Book Value	645us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember	698us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember
Other [Member]
Intangible Assets Net Excluding Goodwill [Line Items]
Gross	1,058nov_IntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = nov_OtherFiniteLivedIntangibleAssetsMember	1,175nov_IntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = nov_OtherFiniteLivedIntangibleAssetsMember
Accumulated Amortization	(510)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = nov_OtherFiniteLivedIntangibleAssetsMember	(407)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = nov_OtherFiniteLivedIntangibleAssetsMember
Net Book Value	$ 548us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = nov_OtherFiniteLivedIntangibleAssetsMember	$ 768us-gaap_IntangibleAssetsNetExcludingGoodwill / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = nov_OtherFiniteLivedIntangibleAssetsMember

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Intangible Assets Gross.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

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-Section 50

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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