Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Disaggregation of Revenue [Line Items]      
Total operating revenues $ 461,279 $ 771,081  
Refunds issued 31,900 43,700  
Air traffic liability $ 509,172   $ 401,966
Minimum      
Disaggregation of Revenue [Line Items]      
Credit shell term expiration 60 days    
Maximum      
Disaggregation of Revenue [Line Items]      
Credit shell term expiration 12 months    
DOT—Domestic      
Disaggregation of Revenue [Line Items]      
Total operating revenues $ 408,693 697,828  
DOT—Latin America      
Disaggregation of Revenue [Line Items]      
Total operating revenues 52,586 73,253  
Passenger      
Disaggregation of Revenue [Line Items]      
Total operating revenues 450,335 753,550  
Fare      
Disaggregation of Revenue [Line Items]      
Total operating revenues 174,287 321,447  
Non-fare      
Disaggregation of Revenue [Line Items]      
Total operating revenues 276,048 432,103  
Other      
Disaggregation of Revenue [Line Items]      
Total operating revenues $ 10,944 $ 17,531