Commitments and Contingencies - Future Minimum Lease Payments Under Noncancelable Operating Leases (Details) $ in Thousands	Sep. 30, 2015 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
remainder of 2015	$ 62,036
Future Minimum Payments Due, 2016	238,132
Future Minimum Payments Due, 2017	226,430
Future Minimum Payments Due, 2018	205,750
Future Minimum Payments Due, 2019	177,060
Future Minimum Payments Due, 2020 and thereafter	723,285
Total minimum lease payments	1,632,693
Aircraft and Spare Engine Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
remainder of 2015	53,847
Future Minimum Payments Due, 2016	213,207
Future Minimum Payments Due, 2017	199,628
Future Minimum Payments Due, 2018	175,867
Future Minimum Payments Due, 2019	147,756
Future Minimum Payments Due, 2020 and thereafter	630,732
Total minimum lease payments	1,421,037
Property Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
remainder of 2015	8,189
Future Minimum Payments Due, 2016	24,925
Future Minimum Payments Due, 2017	26,802
Future Minimum Payments Due, 2018	29,883
Future Minimum Payments Due, 2019	29,304
Future Minimum Payments Due, 2020 and thereafter	92,553
Total minimum lease payments	$ 211,656