Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Federal excise and other passenger taxes and fees payable	$ 59,919	$ 42,064
Salaries and wages	48,810	54,578
Airport obligations	37,906	43,989
Aircraft maintenance	26,132	30,233
Aircraft and facility lease obligations	17,441	10,378
Interest payable	14,240	8,499
Fuel	9,845	14,828
Other	17,639	21,442
Other current liabilities	$ 231,932	$ 226,011