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Acquisitions - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified | 3 Months Ended
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Mar. 31, 2013
All Other Acquisitions [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Share holder received in cash per share | $ 60.00
Aggregate purchase price of acquisitions | $ 2,375
Intangible assets | 967
Weighted average life | 19 years
Customer Relationships [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Intangible assets | 815
Weighted average life | 20 years
Trademarks [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Intangible assets | 58
Weighted average life | 15 years
Other intangible Assets [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Intangible assets | $ 94
Weighted average life | 15 years

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- Definition Business Acquisition Cash Per Share Paid To Shareholders + References No definition available. + Details
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Namespace Prefix: | nov_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

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- Definition Business Acquisition Purchase Price Allocation Intangible Assets + References No definition available. + Details
Name: | nov_BusinessAcquisitionPurchasePriceAllocationIntangibleAssets
Namespace Prefix: | nov_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
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- Definition Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16265-109275 + Details
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- Definition The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 141 -Paragraph 51 -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant