REVENUE - Passenger Revenue Breakout (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue
Total operating revenues	$ 27,483	$ 26,091	$ 23,814
Passenger
Disaggregation of Revenue
Total operating revenues	24,980	23,637	21,408
Passenger non-loyalty
Disaggregation of Revenue
Total operating revenues	20,467	19,073	17,645
Passenger loyalty - air transportation
Disaggregation of Revenue
Total operating revenues	3,484	3,639	3,028
Passenger ancillary sold separately
Disaggregation of Revenue
Total operating revenues	$ 1,029	$ 925	$ 735