Document And Entity Information (USD $)
9 Months Ended
Sep. 30, 2011
Dec. 31, 2010
Entity Registrant NameORBITAL SCIENCES CORP /DE/ 
Entity Central Index Key0000820736 
Current Fiscal Year End Date--12-31 
Entity Well-known Seasoned IssuerYes 
Entity Voluntary FilersNo 
Entity Current Reporting StatusYes 
Entity Filer CategoryLarge Accelerated Filer 
Entity Public Float $ 900,496,000
Entity Common Stock, Shares Outstanding58,747,734 
Document Fiscal Year Focus2011 
Document Fiscal Period FocusQ3 
Document Type10-Q 
Amendment Flagfalse 
Document Period End DateSep. 30, 2011