Commitments and Contingencies (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($) aircraft	Sep. 30, 2015 USD ($) aircraft	Dec. 31, 2014 USD ($)
Supply Commitment [Line Items]
Long-term debt amount	$ 25,000	$ 25,000
Debt Instrument, Term		4 years
Interest rate (as a percent)	3.30%	3.30%
Future minimum rental payments required under operating leases
October through December 2015	$ 93,236	$ 93,236
2016	267,353	267,353
2017	191,506	191,506
2018	153,042	153,042
2019	120,072	120,072
Thereafter	472,800	472,800
Total future lease obligations	$ 1,298,009	$ 1,298,009
E 175
Supply Commitment [Line Items]
Number of aircrafts committed to purchase | aircraft		49
Number of aircraft delivered | aircraft	5	23
Debt issued to purchase of aircraft	$ 113,700	$ 521,200
Debt Instrument, Term		12 years
E 175 | Minimum
Supply Commitment [Line Items]
Interest rate (as a percent)	3.40%	3.40%
E 175 | Maximum
Supply Commitment [Line Items]
Interest rate (as a percent)	4.00%	4.00%
EMB 120
Future minimum rental payments required under operating leases
Total future lease obligations	$ 1,500	$ 1,500	$ 3,800