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