Fair Value Measurements and Derivative Instruments (Derivatives Not Designated as Hedging Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivative	$ (55,664)	$ (50,586)
Foreign exchange contracts | Other income (expense)
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivative	(55,489)	(48,791)
Fuel contracts | Fuel swaps | Other income (expense)
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivative	$ (175)	$ (1,795)