Revenue (Impact of Adjustments in Contract Estimates) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue*	$ 37,925	$ 39,350	[1]	$ 36,193	[1]
Operating Earnings	$ 4,133	$ 4,570	[1]	$ 4,394	[1]
Diluted earnings per share	$ 11.00	$ 11.98	[1]	$ 11.18	[1]
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue*	$ 389	$ 342		$ 377
Operating Earnings	$ 283	$ 271		$ 345
Diluted earnings per share	$ 0.78	$ 0.74		$ 0.91

[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.