Fair Value Measurements and Derivative Instruments (Derivatives Not Designated as Hedging Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivative	$ (121,701)	$ 1,431	$ (61,148)
Foreign exchange contracts | Other Income (Expense)
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivative	(18,961)	1,356	(62,423)
Fuel swaps | Other Income (Expense)
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivative	(102,740)	112	114
Fuel swaps | Fuel
Derivative instruments disclosure
Amount of Gain (Loss) Recognized in Income on Derivative	$ 0	$ (37)	$ 1,161