Revenue Recognition - Operating Revenues by Principal Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 883	$ 906	$ 2,698	$ 2,420
Domestic
Disaggregation of Revenue [Line Items]
Total operating revenues	818	832	2,476	2,197
Latin America
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 65	$ 74	$ 222	$ 223