Changes in Contract Estimates at Completion (Schedule of Change in Accounting Estimate) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Change in Accounting Estimate [Line Items]
Operating profit (loss)	$ 1,343	$ 142	$ 434	$ (3,760)	$ 1,295	$ 3,638	$ (2,031)	$ (1,889)
Income (loss) from continuing operations attributable to common shareowners	$ 1,400		$ 151			$ 3,212	$ (3,255)
Diluted earnings (loss) per share from continuing operations attributable to common shareholders (1)	$ 0.93		$ 0.10			$ 2.13	$ (2.48)
Contracts Accounted for under Percentage of Completion [Member]
Change in Accounting Estimate [Line Items]
Operating profit (loss)	$ 25		$ (462)			$ 64	$ (592)
Income (loss) from continuing operations attributable to common shareowners	$ 20		$ (365)			$ 51	$ (468)
Diluted earnings (loss) per share from continuing operations attributable to common shareholders (1)	$ 0.01		$ (0.24)			$ 0.03	$ (0.36)