Acquisitions and Divestitures, Goodwill and Intangible Assets - Changes In Amount of Goodwill (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Apr. 01, 2018		Sep. 30, 2018		Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, beginning of period	[1]	$ 11,914		$ 11,955
Change in reporting unit composition	[2]			0
Acquisitions/divestitures	[3]	16		7,945
Other	[4]	25		(414)
Goodwill, end of period		11,955	[1]	19,486	[5]
Aerospace
Goodwill [Roll Forward]
Goodwill, beginning of period	[1]	2,638		2,678
Change in reporting unit composition	[2]			0
Acquisitions/divestitures	[3]	0		148
Other	[4]	40		(37)
Goodwill, end of period		2,678	[1]	2,789	[5]
Combat Systems
Goodwill [Roll Forward]
Goodwill, beginning of period	[1]	2,677		2,663
Change in reporting unit composition	[2]			0
Acquisitions/divestitures	[3]	0		0
Other	[4]	(14)		(21)
Goodwill, end of period		2,663	[1]	2,642	[5]
Information Systems and Technology
Goodwill [Roll Forward]
Goodwill, beginning of period	[1]	6,302		6,317
Change in reporting unit composition	[2]			(6,317)
Acquisitions/divestitures	[3]	16		0
Other	[4]	(1)		0
Goodwill, end of period		6,317	[1]	0	[5]
Accumulated impairment loss		1,900				$ 1,900
Information Technology
Goodwill [Roll Forward]
Goodwill, beginning of period	[1]	0		0
Change in reporting unit composition	[2]			2,076
Acquisitions/divestitures	[3]	0		7,796
Other	[4]	0		(347)
Goodwill, end of period		0	[1]	9,525	[5]
Accumulated impairment loss				526
Mission Systems
Goodwill [Roll Forward]
Goodwill, beginning of period	[1]	0		0
Change in reporting unit composition	[2]			4,241
Acquisitions/divestitures	[3]	0		1
Other	[4]	0		(9)
Goodwill, end of period		0	[1]	4,233	[5]
Accumulated impairment loss				1,300
Marine Systems
Goodwill [Roll Forward]
Goodwill, beginning of period	[1]	297		297
Change in reporting unit composition	[2]			0
Acquisitions/divestitures	[3]	0		0
Other	[4]	0		0
Goodwill, end of period		$ 297	[1]	$ 297	[5]

[1] Goodwill in the Information Systems and Technology reporting unit is net of $1.9 billion of accumulated impairment losses.

[2] Concurrent with the acquisition of CSRA, we reorganized our Information Systems and Technology operating segment into the Information Technology and Mission Systems segments. See Note A for further discussion of the segment reorganization. This reorganization similarly changed the composition of our reporting units. Accordingly, goodwill of the Information Systems and Technology reporting unit was reassigned to the Information Technology and Mission Systems reporting units using a relative fair value allocation approach as of the date of the reorganization.

[3] Includes adjustments during the purchase price allocation period. Activity in the first quarter of 2018 also includes an allocation of goodwill associated with the sale of the commercial health products business discussed above.

[4] Consists primarily of adjustments for foreign currency translation. Activity in the six-month period ended September 30, 2018, also includes an allocation of goodwill in our Information Technology reporting unit associated with the operations classified as held for sale on the unaudited Consolidated Balance Sheet on September 30, 2018.

[5] Goodwill in the Information Technology and Mission Systems reporting units is net of $526 and $1.3 billion of accumulated impairment losses, respectively.