Fair Value Measurements and Derivative Instruments (Derivatives Not Designated as Hedging Instruments) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivative	$ (21,024)	$ (1,519)
Foreign exchange contracts | Other income (expense)
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivative	(21,244)	7,152
Fuel contracts | Fuel swaps | Other income (expense)
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivative	243	(3,058)
Fuel contracts | Options | Other income (expense)
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivative	$ (23)	$ (5,613)