Summary of Significant Accounting Policies - Primary Components of Non-Ticket Revenue (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	$ 535,596	$ 381,536	$ 243,296
Baggage
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	217,536	168,290	91,393
Passenger usage fee
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	149,577	71,757	47,367
Advance seat selection
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	48,956	42,112	32,512
Change fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	27,762	25,927	23,120
Other
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	$ 91,765	$ 73,450	$ 48,904