Commitments and Contingencies - Future Minimum Lease Payments Under Noncancelable Operating Leases (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Operating Leased Assets [Line Items]
Capital Leases of Lessee, Lease Term	3 years
Total Operating and Capital Lease Obligations
remainder of 2017	$ 130,001
2018	248,156
2019	221,750
2020	202,240
2021	183,441
2022 and thereafter	643,372
Total minimum lease payments	1,628,960
Aircraft and Spare Engine Leases [Member]
Capital Leases
remainder of 2017	268
2018	537
2019	504
2020	188
2021	28
2022 and thereafter	0
Operating Leases
remainder of 2017	108,237
2018	206,595
2019	188,212
2020	180,235
2021	170,613
2022 and thereafter	570,087
Total minimum lease payments	1,423,979
Total Operating and Capital Lease Obligations
Capital Leases, Future Minimum Payments Due	1,525
Capital Leases, Future Minimum Payments, Interest Included in Payments	136
Capital Lease Obligations, Current	460
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	1,389
Capital Lease Obligations, Noncurrent	929
Property Facility Leases [Member]
Operating Leases
remainder of 2017	21,496
2018	41,024
2019	33,034
2020	21,817
2021	12,800
2022 and thereafter	73,285
Total minimum lease payments	$ 203,456