Property and Equipment (Schedule of Property and Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	$ 1,602,168	$ 1,486,736
Accumulated depreciation	(667,949)	(611,335)
Property and equipment, net	934,219	875,401
Flight Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	1,415,283	1,372,099
Ground equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	37,923	36,593
facilities, leasehold improvements and office equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	26,347	25,327
Construction in Progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross	$ 122,615	$ 52,717