Accrued Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Payables and Accruals [Abstract]
Aircraft maintenance	$ 34,881	$ 22,319
Federal excise and other passenger taxes and fees payable	27,507	23,401
Salaries and wages	20,933	21,057
Airport expenses	15,919	16,024
Income tax payable	10,437	0
Aircraft and facility rent	8,074	8,020
Tax receivable agreement	7,987	7,987
Fuel	7,277	11,219
Other	16,918	11,287
Accrued liabilities	$ 149,933	$ 121,314