v3.24.0.1
Long-term Debt, Short-term Borrowings and Finance Lease Obligations - Net of Debt Acquisition Costs (Details) - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Debt Instrument [Line Items]    
Present value of future minimum lease payment $ 0 $ 2
Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 4,716 3,645
Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 4,691 2,848
Fixed rate specialty bonds, due through 2036 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 42 42
Fixed rate specialty bonds, due through 2036 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 43 43
2019-1 Series AA, due through 2032 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 476 504
2019-1 Series AA, due through 2032 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 474 345
2019-1 Series A, due through 2028 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 149 157
2019-1 Series A, due through 2028 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 150 124
2019-1 Series B, due through 2027 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 70 82
2019-1 Series B, due through 2027 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 86 87
2020-1 Series A, due through 2032 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 506 546
2020-1 Series A, due through 2032 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 597 457
2020-1 Series B, due through 2028 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 117 135
2020-1 Series B, due through 2028 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 150 142
Fixed rate enhanced equipment notes, due through 2023 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 0 61
Fixed rate enhanced equipment notes, due through 2023 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 0 60
Fixed rate equipment notes, due through 2028 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 322 447
Fixed rate equipment notes, due through 2028 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 305 422
Floating rate equipment notes, due through 2030 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 109 56
Floating rate equipment notes, due through 2030 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 113 49
Unsecured CARES Act Payroll Support Program loan, due through 2030 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 259 259
Unsecured CARES Act Payroll Support Program loan, due through 2030 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 184 126
Aircraft sale-leaseback transactions, due through 2035 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 1,648 341
Aircraft sale-leaseback transactions, due through 2035 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 1,738 329
Unsecured Consolidated Appropriations Act Payroll Support Program Extension loan, due through 2031 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 144 144
Unsecured Consolidated Appropriations Act Payroll Support Program Extension loan, due through 2031 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 101 68
Unsecured American Rescue Plan Act of 2021 Payroll Support loan, due through 2031 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt 132 132
Unsecured American Rescue Plan Act of 2021 Payroll Support loan, due through 2031 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value 93 62
0.50% convertible senior notes, due through 2026    
Debt Instrument [Line Items]    
Long-term debt $ 750 750
Debt instrument, interest rate, stated percentage 0.50%  
0.50% convertible senior notes, due through 2026 | Carrying Value    
Debt Instrument [Line Items]    
Long-term debt $ 742 739
0.50% convertible senior notes, due through 2026 | Estimated Fair Value    
Debt Instrument [Line Items]    
Long-term debt, fair value $ 657 $ 534