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Acquisitions - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	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

X

- Definition

Business Acquisition Cash Per Share Paid To Shareholders

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

X

- Definition

Business Acquisition Purchase Price Allocation Intangible Assets

+ References

No definition available.

+ Details

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Namespace Prefix:	nov_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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X

- Details

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

X

- 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

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X

- 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.

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