Investments - Equity Method Investments (Details) - USD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Grupo Aeromexico    
Equity Method Investments    
Ownership interest (percent) 51.00% 51.00%
Carrying value $ 833 $ 897
Voting interest limit per bylaws (percent) 49.00%  
Virgin Atlantic Limited    
Equity Method Investments    
Ownership interest (percent) 49.00% 49.00%
Carrying value $ 375 $ 383
AirCo    
Equity Method Investments    
Ownership interest (percent) 49.00% 49.00%
Carrying value $ 142 $ 109