Acquisitions and Divestitures, Goodwill, and Intangible Assets (Changes In Goodwill) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Apr. 01, 2018		Dec. 31, 2018		Dec. 31, 2019		Mar. 31, 2019	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, beginning of period		$ 11,914		$ 11,955		$ 19,594
Acquisitions/divestitures		16	[1]	7,821	[1]	101
Other		25	[2]	(182)	[2]	(18)
Change in reporting unit composition				0
Goodwill, end of period		11,955		19,594		19,677
Aerospace
Goodwill [Roll Forward]
Goodwill, beginning of period		2,638		2,678	[3]	2,813	[3]
Acquisitions/divestitures	[1]	0		183		3
Other	[2]	40		(48)		15
Change in reporting unit composition	[4]			0
Goodwill, end of period		2,678	[3]	2,813	[3]	2,831	[5]
Combat Systems
Goodwill [Roll Forward]
Goodwill, beginning of period		2,677		2,663	[3]	2,633	[3]
Acquisitions/divestitures	[1]	0		30		15
Other	[2]	(14)		(60)		33
Change in reporting unit composition	[4]			0
Goodwill, end of period		2,663	[3]	2,633	[3]	2,681	[5]
Information Systems and Technology
Goodwill [Roll Forward]
Goodwill, beginning of period	[3]	6,302		6,317		0
Acquisitions/divestitures	[1]	16		0		0
Other	[2]	(1)		0		0
Change in reporting unit composition	[4]			(6,317)
Goodwill, end of period		6,317	[3]	0	[3]	0	[5]
Accumulated impairment loss				1,900				$ 1,900	$ 1,900
Information Technology
Goodwill [Roll Forward]
Goodwill, beginning of period	[3]	0		0		9,622
Acquisitions/divestitures	[1]	0		7,601		77
Other	[2]	0		(55)		1
Change in reporting unit composition	[4]			2,076
Goodwill, end of period		0	[3]	9,622	[3]	9,700	[5]
Accumulated impairment loss						536
Mission Systems
Goodwill [Roll Forward]
Goodwill, beginning of period		0		0	[3]	4,229	[3]
Acquisitions/divestitures	[1]	0		7		6
Other	[2]	0		(19)		(67)
Change in reporting unit composition	[4]			4,241
Goodwill, end of period		0	[3]	4,229	[3]	4,168	[5]
Accumulated impairment loss						1,300
Marine Systems
Goodwill [Roll Forward]
Goodwill, beginning of period		297		297	[3]	297	[3]
Acquisitions/divestitures	[1]	0		0		0
Other	[2]	0		0		0
Change in reporting unit composition	[4]			0
Goodwill, end of period		$ 297	[3]	$ 297	[3]	$ 297	[5]

[1] Includes adjustments during the purchase price allocation period. Activity in the first quarter of 2018 and the nine-month period ended December 31, 2018, also includes an allocation of goodwill associated with the sale of the commercial health products business and an allocation of goodwill associated with the sale of a public-facing contact-center business, respectively, as discussed above.

[2] Consists primarily of adjustments for foreign currency translation. Activity in the nine-month period ended December 31, 2018, also includes an allocation of goodwill in our Information Technology reporting unit associated with certain operations classified as held for sale on the Consolidated Balance Sheet on December 31, 2018. Activity in 2019 also includes an allocation of goodwill in our Mission Systems reporting unit associated with a non-core operation classified as held for sale on the Consolidated Balance Sheet on December 31, 2019.

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

[4] Concurrent with the acquisition of CSRA, we reorganized our Information Systems and Technology operating segment, in accordance with the nature of the segment’s products and services, into the Information Technology and Mission Systems segments. 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

[5] Goodwill in the Information Technology and Mission Systems reporting units is net of $536 and $1.3 billion of accumulated impairment losses, respectively.