Document and Company Information (USD $)
In Billions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2009
Feb. 16, 2010
Jun. 30, 2009
Document and Company Information [Abstract]      
Entity Registrant Name NATIONAL OILWELL VARCO INC    
Entity Central Index Key 0001021860    
Document Type 10-K    
Document Period End Date Dec. 31, 2009    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 13.7
Entity Common Stock, Shares Outstanding   418,452,756