Investments - Narrative (Details)
1 Months Ended 3 Months Ended 12 Months Ended
Jan. 31, 2020
USD ($)
$ / shares
Dec. 31, 2019
USD ($)
numberOfAircraft
Dec. 31, 2019
USD ($)
numberOfAircraft
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]            
Net gain on equity investments     $ 119,000,000 $ 38,000,000 $ 0  
GOL            
Schedule of Equity Method Investments [Line Items]            
Ownership stake in equity securities sold during period (percent)   9.00%        
Proceeds from sale of ownership stake in equity securities   $ 278,000,000        
Term loan facility | Financial Guarantee            
Schedule of Equity Method Investments [Line Items]            
Guarantee borrowings on third party debt     $ 300,000,000      
Guarantee borrowings on third party debt, term (in years)     5 years      
LATAM            
Schedule of Equity Method Investments [Line Items]            
Planned investment to support establishment of strategic alliance   $ 350,000,000 $ 350,000,000      
Payments to support establishment of strategic alliance     $ 200,000,000      
LATAM | A350-900            
Schedule of Equity Method Investments [Line Items]            
Number of aircraft agreed to acquire | numberOfAircraft   4 4      
Number of aircraft commitments planned to be assumed | numberOfAircraft   10 10      
LATAM            
Schedule of Equity Method Investments [Line Items]            
Planned investment in strategic alliance (percent)           20.00%
LATAM | Subsequent event            
Schedule of Equity Method Investments [Line Items]            
Ownership interest (percent) 20.00%          
Equity investment purchase price per share (usd per share) | $ / shares $ 16          
Payment to acquire equity investment $ 1,900,000,000          
Wheels Up | Subsequent event            
Schedule of Equity Method Investments [Line Items]            
Ownership interest (percent) 27.00%