Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Federal excise and other passenger taxes and fees payable	$ 38,141	$ 42,628
Salaries and wages	32,501	34,209
Airport obligations	30,024	21,726
Aircraft and facility lease obligations	22,196	10,089
Aircraft maintenance	21,506	16,127
Fuel	9,403	9,508
Federal and state income tax payable	0	3,286
Other	22,488	15,348
Other current liabilities	176,259	$ 152,921
Effect of change in tax method	$ 35,100