Fair Value Measurements and Derivative Instruments - Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (8,205)	$ (24,940)	$ (124,736)	$ (24,229)
Foreign currency forward contracts | Other income (expense)
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivatives	4,907	(26,035)	(35,265)	(25,189)
Fuel swaps | Other income (expense)
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivatives	(13,112)	1,095	(89,471)	974
Fuel swaps | Fuel
Derivative Instruments
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 0	$ 0	$ 0	$ (14)