Goodwill and Other Purchased Intangible Assets Goodwill Rollforward (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill (Table Amounts)
Beginning balance	$ 18,708	$ 18,672
Acquisition of Orbital ATK		37
Reclassification to assets of disposal group held for sale	(1,195)
Other	5	(1)
Ending balance	17,518	18,708
Aeronautics Systems
Goodwill (Table Amounts)
Beginning balance	3,467	3,467
Acquisition of Orbital ATK		0
Reclassification to assets of disposal group held for sale	0
Other	0	0
Ending balance	3,467	3,467
Defense Systems
Goodwill (Table Amounts)
Beginning balance	4,376	4,377
Acquisition of Orbital ATK		0
Reclassification to assets of disposal group held for sale	(966)
Other	5	(1)
Ending balance	3,415	4,376
Mission Systems
Goodwill (Table Amounts)
Beginning balance	6,062	6,062
Acquisition of Orbital ATK		0
Reclassification to assets of disposal group held for sale	(181)
Other	0	0
Ending balance	5,881	6,062
Space Systems
Goodwill (Table Amounts)
Beginning balance	4,803	4,766
Acquisition of Orbital ATK		37
Reclassification to assets of disposal group held for sale	(48)
Other	0	0
Ending balance	$ 4,755	$ 4,803