Accrued Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Payables and Accruals [Abstract]
Federal excise and other passenger taxes and fees payable	$ 36,006	$ 26,979
Salaries and wages	28,640	26,174
Aircraft maintenance	23,322	36,165
Airport expenses	17,322	17,109
Fuel	11,037	13,819
Federal and state income tax payable	9,091	794
Aircraft and facility rent	8,605	7,993
Other	12,601	16,229
Other current liabilities	$ 146,624	$ 145,262