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Commitments and Contingencies - Additional Information (Detail) (Robbins and Myers [Member], USD $) |  | 3 Months Ended
--- | --- | ---
Feb. 20, 2013 Maximum [Member] | Sep. 30, 2014 DOJ [Member] | Sep. 30, 2014 BIS [Member]
Commitment And Contingencies [Line Items] |  |  |
Litigation settlement expense |  | $ 1,033,000 | $ 600,000
Alleged violations involved in goods 2005 and 2006 | $ 75,000 |  |

X
- Definition Alleged violations involved in goods + References No definition available. + Details
Name: | nov_AllegedViolationsInvolvedInGoods
Namespace Prefix: | nov_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | nov_CommitmentAndContingenciesLineItems
Namespace Prefix: | nov_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees. + References No definition available. + Details
Name: | us-gaap_LitigationSettlementExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration