Summary of Significant Accounting Policies - Primary Components of Non-Ticket Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Product Information [Line Items]
Non-ticket revenue	$ 972,125	$ 786,608	$ 668,367
Baggage
Product Information [Line Items]
Non-ticket revenue	381,386	318,103	275,958
Passenger usage fee
Product Information [Line Items]
Non-ticket revenue	298,092	221,992	188,911
Advance seat selection
Product Information [Line Items]
Non-ticket revenue	97,786	76,270	59,241
Service charges for changes and cancellations
Product Information [Line Items]
Non-ticket revenue	43,756	38,388	32,546
Other
Product Information [Line Items]
Non-ticket revenue	$ 151,105	$ 131,855	$ 111,711