Revenue Recognition - Passenger Revenue (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Operating revenue	$ 4,150	$ 8,592
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	2,748	7,569
Ticket
Disaggregation of Revenue [Line Items]
Operating revenue	2,277	6,511
Loyalty travel awards
Disaggregation of Revenue [Line Items]
Operating revenue	241	543
Travel-related services
Disaggregation of Revenue [Line Items]
Operating revenue	$ 230	$ 515

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details