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Business Segments - Additional Information (Detail) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2013 | Jun. 30, 2013
Segment Reporting [Abstract] |  |
Revenue from shipyard customer | 10.00% | 10.00%

X
- Definition Revenue from shipyard customer. + References No definition available. + Details
Name: | nov_RevenueFromCustomer
Namespace Prefix: | nov_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SegmentReportingAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration