v3.24.0.1
Long-term Debt, Short-term Borrowings and Finance Lease Obligations - Fixed Rate Notes (Details)
12 Months Ended
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
aircraft
Aug. 31, 2020
USD ($)
aircraft
Dec. 31, 2019
USD ($)
aircraft
Nov. 30, 2019
USD ($)
aircraft
Dec. 31, 2018
USD ($)
aircraft
Mar. 30, 2014
USD ($)
aircraft
Apr. 30, 2013
USD ($)
Fixed rate specialty bonds, due through 2036                
Debt Instrument [Line Items]                
Debt instrument, face amount               $ 42,000,000
Debt instrument, net amount               43,000,000
Debt instrument, unamortized premium               $ 1,000,000
Secured debt $ 43,000,000 $ 43,000,000            
Fixed rate enhanced equipment notes, 2020-1A and B | Long-term Debt                
Debt Instrument [Line Items]                
Debt instrument, face amount     $ 808,000,000   $ 772,000,000      
2019-1 Series B, due through 2027                
Debt Instrument [Line Items]                
Secured debt 71,000,000 83,000,000            
2019-1 Series B, due through 2027 | Long-term Debt                
Debt Instrument [Line Items]                
Debt instrument, face amount     $ 115,000,000          
Debt instrument, interest rate, stated percentage     8.00%          
2019-1 Series B, due through 2027 | Long-term Debt | Airbus A321                
Debt Instrument [Line Items]                
Number of aircraft, secured debt transactions | aircraft     24   25      
2020-1 Series A, due through 2032                
Debt Instrument [Line Items]                
Secured debt 511,000,000 552,000,000            
2020-1 Series A, due through 2032 | Long-term Debt                
Debt Instrument [Line Items]                
Debt instrument, face amount     $ 636,000,000   $ 589,000,000      
Debt instrument, interest rate, stated percentage     4.00%   2.75%      
2020-1 Series B, due through 2028                
Debt Instrument [Line Items]                
Secured debt 118,000,000 136,000,000            
2020-1 Series B, due through 2028 | Long-term Debt                
Debt Instrument [Line Items]                
Debt instrument, face amount     $ 172,000,000   $ 183,000,000      
Debt instrument, interest rate, stated percentage     7.75%   2.95%      
Fixed rate enhanced equipment notes, due through 2023                
Debt Instrument [Line Items]                
Secured debt 0 61,000,000            
Fixed rate enhanced equipment notes, due through 2023 | Secured Debt                
Debt Instrument [Line Items]                
Debt instrument, face amount             $ 226,000,000  
Number of aircraft, secured debt transactions | aircraft             8  
Repayments of debt 61,000,000              
Fixed rate enhanced equipment notes, due through 2023 | Secured Debt | A-320-200                
Debt Instrument [Line Items]                
Number of new aircraft held as security | aircraft             14  
Fixed rate equipment notes, due through 2028                
Debt Instrument [Line Items]                
Debt instrument, face amount   11,000,000   $ 219,000,000   $ 567,000,000    
Secured debt $ 323,000,000 $ 448,000,000            
Fixed rate equipment notes, due through 2028 | Secured Debt | A-320                
Debt Instrument [Line Items]                
Number of new aircraft held as security | aircraft       10   14    
Fixed rate equipment notes, due through 2028 | Secured Debt | A-321                
Debt Instrument [Line Items]                
Number of new aircraft held as security | aircraft       2   10    
Fixed rate equipment notes, due through 2028 | Secured Debt | E190                
Debt Instrument [Line Items]                
Number of aircraft, secured debt transactions | aircraft   5