Summary of Significant Accounting Policies - Primary Components of Non-Ticket Revenue (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	$ 668,367	$ 535,596	$ 381,536
Baggage
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	275,958	217,536	168,290
Passenger usage fee
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	188,911	149,577	71,757
Advance seat selection
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	59,241	48,956	42,112
Change fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	32,546	27,762	25,927
Other
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-ticket revenue	$ 111,711	$ 91,765	$ 73,450