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v3.25.1

Financing Activities - Narrative (Details) |  |  |  |  | 1 Months Ended | 3 Months Ended | 4 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 17, 2025 USD ($) | Mar. 31, 2025 USD ($) program | Feb. 19, 2025 $ / shares | May 01, 2020 USD ($) $ / shares | Apr. 30, 2025 $ / shares shares | Feb. 28, 2025 USD ($) shares | Jan. 31, 2025 shares | Mar. 31, 2025 USD ($) program aircraft | Dec. 31, 2024 USD ($) aircraft | Mar. 31, 2024 USD ($) | Apr. 30, 2025 shares | Jan. 31, 2025 $ / shares shares | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payroll support programs | program |  | 3 |  |  |  |  |  | 3 |  |  |  |  |  |
Proceeds from sale-leaseback transactions |  |  |  |  |  |  |  | $ 24,000,000 |  | $ 0 |  |  |  |
Gain on sale-leaseback transactions |  |  |  |  |  |  |  | 3,000,000 |  | 0 |  |  |  |
Repurchase of common stock |  |  |  |  |  |  |  | $ 750,000,000 |  | 0 |  |  |  |
First Quarter 2025 ASR Program |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common stock |  |  |  |  |  | $ 750,000,000 |  |  |  |  |  |  |  |
Shares acquired in repurchase (in shares) | shares |  |  |  |  |  | 19,867,550 |  |  |  |  |  |  |  |
Percentage of total shares acquired on initial delivery |  |  |  |  |  | 0.80 |  |  |  |  |  |  |  |
Initial price paid per share for shares repurchased (in dollars per share) | $ / shares |  |  | $ 30.20 |  |  |  |  |  |  |  |  |  |  |
Fourth Quarter 2024 ASR Program |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares acquired in repurchase (in shares) | shares |  |  |  |  |  |  | 1,010,663 |  |  |  |  | 7,806,450 |  |
Shares repurchased, average purchase price per share (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 32.02 |  |
Subsequent Event | First Quarter 2025 ASR Program |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares acquired in repurchase (in shares) | shares |  |  |  |  | 4,242,267 |  |  |  |  |  | 24,109,817 |  |  |
Shares repurchased, average purchase price per share (in dollars per share) | $ / shares |  |  |  |  | $ 31.11 |  |  |  |  |  |  |  |  |
Air Transportation Equipment | Boeing 737 800 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft sale agreements | aircraft |  |  |  |  |  |  |  |  | 36 |  |  |  |  |
Number of aircrafts sold | aircraft |  |  |  |  |  |  |  | 1 |  |  |  |  |  |
Proceeds from sale-leaseback transactions |  |  |  |  |  |  |  | $ 24,000,000 |  |  |  |  |  |
Sale leaseback transaction, lease term (in years) |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |
Gain on sale-leaseback transactions |  |  |  |  |  |  |  | $ 3,000,000 |  |  |  |  |  |
Convertible Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  | $ 1,600,000,000 |  | $ 2,300,000,000 |  |  |  | $ 1,600,000,000 | $ 1,600,000,000 |  |  |  |  |
Conversion ratio |  | 0.0275005 |  | 0.0259909 |  |  |  |  |  |  |  |  |  |
Initial conversion price (in USD per share) | $ / shares |  |  |  | $ 38.48 |  |  |  |  |  |  |  |  |  |
Principal amount of debt repurchased |  |  |  |  |  |  |  |  |  |  |  |  | $ 689,000,000 | $ 689,000,000
Term (in years) |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |
Convertible Debt | 1.25% Convertible Notes (a) |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amounts outstanding |  | $ 1,611,000,000 |  |  |  |  |  | $ 1,611,000,000 |  |  |  |  |  |
Convertible Debt | 1.25% Convertible Notes (a) | Level 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate |  | 1.25% |  | 1.25% |  |  |  | 1.25% |  |  |  |  |  |
Notes Due 2027 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Effective interest rate |  | 1.90% |  |  |  |  |  | 1.90% |  |  |  |  |  |
Line of Credit |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowing capacity |  | $ 1,000,000,000 |  |  |  |  |  | $ 1,000,000,000 |  |  |  |  |  |
Amounts outstanding |  | 0 |  |  |  |  |  | 0 |  | $ 0 |  |  |  |
Unsecured Debt | 1.000% Payroll Support Program Loan due 2030 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amounts outstanding |  | 976,000,000 |  |  |  |  |  | 976,000,000 |  |  |  |  |  |
Unsecured Debt | 1.000% Payroll Support Program Loan due 2030 | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Early repayments of loan | $ 976,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Unsecured Debt | 1.000% Payroll Support Program Loan due 2031 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amounts outstanding |  | 566,000,000 |  |  |  |  |  | 566,000,000 |  |  |  |  |  |
Unsecured Debt | 1.000% Payroll Support Program Loan Due 2031 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amounts outstanding |  | $ 526,000,000 |  |  |  |  |  | $ 526,000,000 |  |  |  |  |  |

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