Fair Value Measurements and Derivative Instruments - Balance Sheet (Details) - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014
Asset Derivatives
Asset Derivatives		$ 118,046	$ 63,981
Liability Derivatives
Liability Derivatives		726,610	767,635
Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	[1]	118,046	63,981
Liability Derivatives
Liability Derivatives	[1]	699,475	767,635
Designated as Hedging Instrument | Foreign currency collar options | Other assets
Asset Derivatives
Asset Derivatives	[1]	0	0
Designated as Hedging Instrument | Foreign currency collar options | Derivative financial instruments
Liability Derivatives
Liability Derivatives	[1]	0	21,855
Not Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives		0	0
Liability Derivatives
Liability Derivatives		27,135	0
Interest rate swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	7,266	0
Interest rate swaps | Designated as Hedging Instrument | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	[1]	62,402	65,768
Foreign currency forward contracts | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	0	63,981
Foreign currency forward contracts | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	107,900	0
Liability Derivatives
Liability Derivatives	[1]	291,503	17,619
Foreign currency forward contracts | Designated as Hedging Instrument | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	[1]	8,545	164,627
Fuel swaps | Designated as Hedging Instrument | Swaps | Other assets
Asset Derivatives
Asset Derivatives	[1]	1,862	0
Fuel swaps | Designated as Hedging Instrument | Swaps | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	1,018	0
Liability Derivatives
Liability Derivatives	[1]	162,512	227,512
Fuel swaps | Designated as Hedging Instrument | Swaps | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	[1]	174,513	270,254
Fuel swaps | Not Designated as Hedging Instrument | Swaps | Other assets
Asset Derivatives
Asset Derivatives		0	0
Fuel swaps | Not Designated as Hedging Instrument | Swaps | Derivative financial instruments
Asset Derivatives
Asset Derivatives		0	0
Liability Derivatives
Liability Derivatives		14,599	0
Fuel swaps | Not Designated as Hedging Instrument | Swaps | Other long-term Liabilities
Liability Derivatives
Liability Derivatives		$ 12,536	$ 0

[1] Accounting Standard Codification 815-20 “Derivatives and Hedging.”