Special Charges (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) aircraft	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Purchase of property and equipment	$ 541,122	$ 548,800	$ 186,569
Special charges	$ 37,189	$ 673	$ 45
Airbus A319 | Aircraft
Property, Plant and Equipment [Line Items]
Number of previously leased aircraft purchased | aircraft	7
Purchase price	$ 147,700
Purchase of property and equipment	107,100
Value of noncash consideration	40,600
Fair value of assets acquired	95,700
Special charges	37,200
Airbus A319 | Aircraft | Supplemental Rent and Other [Member]
Property, Plant and Equipment [Line Items]
Value of noncash consideration	$ 14,800