XML 68 R41.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Business Segments - Additional Information (Detail) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2012 | Sep. 30, 2011 | Sep. 30, 2012 | Sep. 30, 2011
Segment Reporting Information [Line Items] |  |  |  |
Revenue from shipyard customer | 9.00% | 13.00% | 10.00% | 12.00%

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