XML 53 R42.htm IDEA: XBRL DOCUMENT v3.10.0.1
Revenue - Air Traffic Liability Rollforward (Details) - USD ($)
$ in Millions
 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Air Traffic Liability Roll Forward    
ATL, beginning balance $ 4,565 $ 4,221
Current Period Sales 16,200 15,696
Revenue amounts in beginning balance [1] (3,098) (2,780)
Revenue from Current Period Sales [1] (12,084) (12,114)
ATL, ending balance $ 5,583 $ 5,023
[1] (a) Does not include certain ancillary revenues that are purchased on the day of travel, which do not flow through Air traffic liability.