Revenue (Revenue by Contract Type) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Revenue, Major Customer [Line Items]
Revenue*	$ 37,925	$ 39,350	[1]	$ 36,193	[1]
Aerospace
Revenue, Major Customer [Line Items]
Revenue*	8,075	9,801		8,455
Marine Systems
Revenue, Major Customer [Line Items]
Revenue*	9,979	9,183		8,502
Combat Systems
Revenue, Major Customer [Line Items]
Revenue*	7,223	7,007		6,241
Technologies
Revenue, Major Customer [Line Items]
Revenue*	12,648	13,359		12,995
Fixed-price
Revenue, Major Customer [Line Items]
Revenue*	26,279	27,673		24,606
Fixed-price | Aerospace
Revenue, Major Customer [Line Items]
Revenue*	7,402	8,949		7,600
Fixed-price | Marine Systems
Revenue, Major Customer [Line Items]
Revenue*	6,924	6,331		5,493
Fixed-price | Combat Systems
Revenue, Major Customer [Line Items]
Revenue*	6,159	6,049		5,406
Fixed-price | Technologies
Revenue, Major Customer [Line Items]
Revenue*	5,794	6,344		6,107
Cost-reimbursement
Revenue, Major Customer [Line Items]
Revenue*	9,342	8,996		9,087
Cost-reimbursement | Aerospace
Revenue, Major Customer [Line Items]
Revenue*	0	0		0
Cost-reimbursement | Marine Systems
Revenue, Major Customer [Line Items]
Revenue*	3,045	2,839		3,004
Cost-reimbursement | Combat Systems
Revenue, Major Customer [Line Items]
Revenue*	997	894		800
Cost-reimbursement | Technologies
Revenue, Major Customer [Line Items]
Revenue*	5,300	5,263		5,283
Time-and-materials
Revenue, Major Customer [Line Items]
Revenue*	2,304	2,681		2,500
Time-and-materials | Aerospace
Revenue, Major Customer [Line Items]
Revenue*	673	852		855
Time-and-materials | Marine Systems
Revenue, Major Customer [Line Items]
Revenue*	10	13		5
Time-and-materials | Combat Systems
Revenue, Major Customer [Line Items]
Revenue*	67	64		35
Time-and-materials | Technologies
Revenue, Major Customer [Line Items]
Revenue*	$ 1,554	$ 1,752		$ 1,605

[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.