FAIR VALUE MEASUREMENTS - Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Fair Value | ||
| Cash equivalents | $ 3,010 | $ 2,868 |
| Restricted cash equivalents | 108 | 191 |
| Long-term investments and related | 3,572 | 3,644 |
| Fuel hedge contracts | 29 | 1 |
| Level 1 | ||
| Fair Value | ||
| Cash equivalents | 3,010 | 2,868 |
| Restricted cash equivalents | 108 | 191 |
| Long-term investments and related | 3,238 | 3,366 |
| Fuel hedge contracts | 0 | 0 |
| Level 2 | ||
| Fair Value | ||
| Cash equivalents | 0 | 0 |
| Restricted cash equivalents | 0 | 0 |
| Long-term investments and related | 306 | 217 |
| Fuel hedge contracts | 29 | 1 |
| Level 3 | ||
| Fair Value | ||
| Cash equivalents | 0 | 0 |
| Restricted cash equivalents | 0 | 0 |
| Long-term investments and related | 28 | 61 |
| Fuel hedge contracts | $ 0 | $ 0 |
| X | ||||||||||
- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition The aggregate value of all restricted investments. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|