Accrued Liabilities (Details) - USD ($) $ in Thousands |
Mar. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Payables and Accruals [Abstract] | ||
| Salaries, wages and benefits | $ 119,842 | $ 112,838 |
| Federal excise and other passenger taxes and fees payable | 102,661 | 36,884 |
| Airport obligations | 71,933 | 68,677 |
| Aircraft and facility lease obligations | 59,575 | 67,374 |
| Interest payable | 33,301 | 37,202 |
| Aircraft maintenance | 30,857 | 27,466 |
| Fuel | 21,493 | 11,704 |
| Other | 34,164 | 31,469 |
| Other current liabilities | $ 473,826 | $ 393,614 |