Document and Entity Information Document - shares
9 Months Ended
Sep. 30, 2018
Oct. 19, 2018
Document and Entity Information [Abstract]    
Entity Registrant Name NORTHROP GRUMMAN CORP /DE/  
Entity Central Index Key 0001133421  
Document Type 10-Q  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Period End Date Sep. 30, 2018  
Document Fiscal Period Focus Q3  
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 Common Stock, Shares Outstanding   173,619,710