Fair Value Measurements and Derivative Instruments (Derivatives Not Designated as Hedging Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (52,029)	$ (55,664)
Foreign exchange contracts | Other income (expense)
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivatives	(51,029)	(55,489)
Fuel contracts | Other income (expense)
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (1,000)	$ (175)