Revenue (Revenue by Major Products and Services) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Revenue from External Customer [Line Items]
Revenue*	$ 37,925	$ 39,350	[1]	$ 36,193	[1]
Aerospace
Revenue from External Customer [Line Items]
Revenue*	8,075	9,801		8,455
Aerospace | Aircraft manufacturing and completions
Revenue from External Customer [Line Items]
Revenue*	6,115	7,541		6,262
Aerospace | Aircraft services
Revenue from External Customer [Line Items]
Revenue*	1,960	2,260		2,193
Marine Systems
Revenue from External Customer [Line Items]
Revenue*	9,979	9,183		8,502
Marine Systems | Nuclear-powered submarines
Revenue from External Customer [Line Items]
Revenue*	6,938	6,254		5,712
Marine Systems | Surface ships
Revenue from External Customer [Line Items]
Revenue*	2,055	1,912		1,872
Marine Systems | Repair and other services
Revenue from External Customer [Line Items]
Revenue*	986	1,017		918
Combat Systems
Revenue from External Customer [Line Items]
Revenue*	7,223	7,007		6,241
Combat Systems | Military vehicles
Revenue from External Customer [Line Items]
Revenue*	4,687	4,620		4,027
Combat Systems | Weapons systems, armament and munitions
Revenue from External Customer [Line Items]
Revenue*	1,991	1,906		1,798
Combat Systems | Engineering and other services
Revenue from External Customer [Line Items]
Revenue*	545	481		416
Technologies
Revenue from External Customer [Line Items]
Revenue*	12,648	13,359		12,995
Technologies | Information technology services
Revenue from External Customer [Line Items]
Revenue*	7,892	8,422		8,269
Technologies | C4ISR solutions
Revenue from External Customer [Line Items]
Revenue*	$ 4,756	$ 4,937		$ 4,726

[1] *Prior-period information has been restated for the retrospective application of a change in accounting principle related to the amortization of actuarial gains and losses for our qualified U.S. government pension plans, which we adopted in the fourth quarter of 2020. For further discussion of this change in accounting principle, see Note T to the Consolidated Financial Statements.