Summary of Significant Accounting Policies - Marketable Securities and Long-Term Restricted Investments and Spare Parts and Supplies (Details) - USD ($) $ in Thousands |
Jun. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Summary of Significant Accounting Policies [Line Items] | ||
| Inventory allowance | $ 17,116 | $ 17,120 |
| Spare parts and supplies carrying value | 0 | 0 |
| Air Wisconsin | ||
| Summary of Significant Accounting Policies [Line Items] | ||
| Fair value of marketable securities and long-term restricted investments | $ 98,154 | $ 100,815 |