Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Salaries and wages	$ 89,611	$ 89,163
Federal excise and other passenger taxes and fees payable	16,580	65,312
Airport obligations	73,309	80,134
Aircraft maintenance	32,005	38,099
Aircraft and facility lease obligations	20,042	20,656
Fuel	10,020	28,510
Interest payable	18,061	16,941
Other	36,979	34,706
Other current liabilities	$ 296,607	$ 373,521