Commitments and Contingencies - Future Minimum Lease Payments Under Noncancelable Operating Leases (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Future Minimum Payments Due, remainder of 2017	$ 195,026
Future Minimum Payments Due, 2016	246,471
Future Minimum Payments Due, 2017	220,288
Future Minimum Payments Due, 2018	200,379
Future Minimum Payments Due, 2019	180,202
Future Minimum Payments Due, 2020 and thereafter	625,659
Total minimum lease payments	1,668,025
Aircraft and Spare Engine Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Future Minimum Payments Due, remainder of 2017	164,411
Future Minimum Payments Due, 2016	206,845
Future Minimum Payments Due, 2017	188,212
Future Minimum Payments Due, 2018	180,235
Future Minimum Payments Due, 2019	170,613
Future Minimum Payments Due, 2020 and thereafter	570,087
Total minimum lease payments	1,480,403
Property Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Future Minimum Payments Due, remainder of 2017	30,615
Future Minimum Payments Due, 2016	39,626
Future Minimum Payments Due, 2017	32,076
Future Minimum Payments Due, 2018	20,144
Future Minimum Payments Due, 2019	9,589
Future Minimum Payments Due, 2020 and thereafter	55,572
Total minimum lease payments	$ 187,622