Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Salaries and wages	$ 54,578	$ 34,123
Airport obligations	43,989	30,849
Federal excise and other passenger taxes and fees payable	42,064	38,254
Aircraft maintenance	30,233	21,688
Fuel	14,828	7,084
Aircraft and facility lease obligations	10,378	24,014
Interest payable	8,499	12,355
Other	21,442	14,362
Other current liabilities	$ 226,011	$ 182,729