v3.24.0.1
Long-term Debt, Short-term Borrowings and Finance Lease Obligations - Finance Lease Obligations And The Related Weighted Average Interest Rate (Details) - USD ($)
Dec. 31, 2023
Dec. 31, 2022
Debt Instrument [Line Items]    
Present value of future minimum lease payment $ 0 $ 2,000,000
Finance leases 0.00% 6.09%
Total debt and capital lease obligations $ 4,740,000,000 $ 3,676,000,000
Less: Debt acquisition cost (24,000,000) (29,000,000)
Less: Current maturities (307,000,000) (554,000,000)
Long-term debt and finance lease obligations 4,409,000,000 3,093,000,000
Fixed rate specialty bonds, due through 2036    
Debt Instrument [Line Items]    
Secured debt $ 43,000,000 $ 43,000,000
Weighted average interest rate 5.00% 4.90%
2019-1 Series AA, due through 2032    
Debt Instrument [Line Items]    
Secured debt $ 481,000,000 $ 510,000,000
Weighted average interest rate 2.80% 2.80%
2019-1 Series A, due through 2028    
Debt Instrument [Line Items]    
Secured debt $ 150,000,000 $ 159,000,000
Weighted average interest rate 3.00% 3.00%
2019-1 Series B, due through 2027    
Debt Instrument [Line Items]    
Secured debt $ 71,000,000 $ 83,000,000
Weighted average interest rate 8.10% 8.10%
2020-1 Series A, due through 2032    
Debt Instrument [Line Items]    
Secured debt $ 511,000,000 $ 552,000,000
Weighted average interest rate 4.10% 4.10%
2020-1 Series B, due through 2028    
Debt Instrument [Line Items]    
Secured debt $ 118,000,000 $ 136,000,000
Weighted average interest rate 7.80% 7.80%
Fixed rate enhanced equipment notes, due through 2023    
Debt Instrument [Line Items]    
Secured debt $ 0 $ 61,000,000
Weighted average interest rate 0.00% 4.40%
Fixed rate equipment notes, due through 2028    
Debt Instrument [Line Items]    
Secured debt $ 323,000,000 $ 448,000,000
Weighted average interest rate 4.30% 4.20%
Floating rate equipment notes, due through 2030    
Debt Instrument [Line Items]    
Secured debt $ 109,000,000 $ 56,000,000
Weighted average interest rate 7.40% 6.90%
Aircraft sale-leaseback transactions, due through 2035    
Debt Instrument [Line Items]    
Secured debt $ 1,649,000,000 $ 341,000,000
Weighted average interest rate 7.00% 7.30%
Unsecured CARES Act Payroll Support Program loan, due through 2030    
Debt Instrument [Line Items]    
Weighted average interest rate 2.00% 2.00%
Unsecured debt $ 259,000,000 $ 259,000,000
Unsecured Consolidated Appropriations Act Payroll Support Program Extension loan, due through 2031    
Debt Instrument [Line Items]    
Weighted average interest rate 2.00% 2.00%
Unsecured debt $ 144,000,000 $ 144,000,000
Unsecured American Rescue Plan Act of 2021 Payroll Support loan, due through 2031    
Debt Instrument [Line Items]    
Weighted average interest rate 2.00% 2.00%
Unsecured debt $ 132,000,000 $ 132,000,000
0.50% convertible senior notes, due through 2026    
Debt Instrument [Line Items]    
Weighted average interest rate 0.50% 0.50%
Debt instrument, interest rate, stated percentage 0.50%  
Long-term debt $ 750,000,000 $ 750,000,000