Fair Value Measurements and Derivative Instruments - Schedule of Fuel Price Risk (Details) - Fuel Swap Agreements $ in Millions |
Mar. 31, 2024
USD ($)
T
|
Dec. 31, 2023
USD ($)
T
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|---|---|---|
| Derivative Instruments | ||
| Estimated unrealized net gain (loss) associated with cash flow hedges pertaining to fuel swap agreements expected to be reclassified to earnings from accumulated other comprehensive income loss | $ | $ 39 | $ (21) |
| 2024 | ||
| Derivative Instruments | ||
| Fuel Swap Agreements (metric tons) | 789,801 | 1,054,501 |
| Percentage of projected requirements | 62.00% | 61.00% |
| 2025 | ||
| Derivative Instruments | ||
| Fuel Swap Agreements (metric tons) | 773,700 | 685,400 |
| Percentage of projected requirements | 45.00% | 39.00% |
| 2026 | ||
| Derivative Instruments | ||
| Fuel Swap Agreements (metric tons) | 252,700 | 44,200 |
| Percentage of projected requirements | 15.00% | 3.00% |