Commitments and Contingencies Commitments and Contingencies (Schedule of 737 Max Liability) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
737 MAX customer concessions and other considerations liability	$ 3,400
B-737
Commitments And Contingencies [Line Items]
737 MAX customer concessions and other considerations liability	3,443	$ 5,981	$ 5,537	$ 7,389
Payments made to customers	(2,040)	(1,695)
Concessions and other in-kind consideration to customers	(53)	(83)
Accrual for 737 MAX customer concessions and other considerations liability	$ (1)	$ (370)