Acquisitions, Divestitures and Goodwill (Rollforward of Goodwill by Segments) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Goodwill [Roll Forward]      
Beginning balance $ 14,871,000,000 $ 14,788,000,000  
Acquisitions and divestitures (3,000,000) 77,000,000 $ 51,000,000
Effect of foreign exchange rates and other (4,000,000) 6,000,000  
Ending Balance 14,864,000,000 14,871,000,000 14,788,000,000
Integrated Defense Systems      
Goodwill [Roll Forward]      
Beginning balance 1,706,000,000 1,702,000,000  
Acquisitions and divestitures 0 0  
Effect of foreign exchange rates and other (2,000,000) 4,000,000  
Ending Balance 1,704,000,000 1,706,000,000 1,702,000,000
Intelligence, Information and Services      
Goodwill [Roll Forward]      
Beginning balance 2,967,000,000 2,966,000,000  
Acquisitions and divestitures 0 0  
Effect of foreign exchange rates and other (2,000,000) 1,000,000  
Ending Balance 2,965,000,000 2,967,000,000 2,966,000,000
Missile Systems      
Goodwill [Roll Forward]      
Beginning balance 4,154,000,000 4,154,000,000  
Acquisitions and divestitures 0 0  
Effect of foreign exchange rates and other 0 0  
Ending Balance 4,154,000,000 4,154,000,000 4,154,000,000
Space and Airborne Systems      
Goodwill [Roll Forward]      
Beginning balance 4,106,000,000 4,106,000,000  
Acquisitions and divestitures (3,000,000) 0  
Effect of foreign exchange rates and other 0 0  
Ending Balance 4,103,000,000 4,106,000,000 4,106,000,000
Forcepoint      
Goodwill [Roll Forward]      
Beginning balance 1,938,000,000 1,860,000,000  
Acquisitions and divestitures 0 77,000,000  
Effect of foreign exchange rates and other 0 1,000,000  
Ending Balance 1,938,000,000 $ 1,938,000,000 $ 1,860,000,000
Estimated fair value in excess of book value $ 1,000,000,000