Property and Equipment (Schedule of Property and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	$ 1,731,983	$ 1,486,736
Accumulated depreciation	(730,991)	(611,335)
Property and equipment, net	1,000,992	875,401
Flight Equipment [Member]
Property, Plant and Equipment [Line Items]
Operating Leases, Future Minimum Payments Receivable, Current	80,200
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	1,541,872	1,372,099
Operating Leases, Future Minimum Payments Receivable, in Two Years	77,600
Operating Leases, Future Minimum Payments Receivable, in Three Years	45,200
Operating Leases, Future Minimum Payments Receivable, in Four Years	28,500
Operating Leases, Future Minimum Payments Receivable, in Five Years	17,100
Ground equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	49,229	36,593
facilities, leasehold improvements and office equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	27,364	25,327
Construction in Progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	$ 113,518	$ 52,717