REVENUE - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Residual travel funds (as a percent)	1600.00%	2800.00%	200.00%
Remaining customer travel funds	$ 1,300
Loyalty points, redemption period (in years)	2 years
Total operating revenues	$ 15,790	$ 9,048	$ 22,428
Chase Bank USA Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total operating revenues	$ 1,400	$ 1,100	$ 1,300