Fair Value Measurements and Derivative Instruments - Balance Sheet (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Asset Derivatives
Asset Derivatives		$ 113,279	$ 63,981
Liability Derivatives
Liability Derivatives		925,202	767,635
Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	[1]	109,359	63,981
Liability Derivatives
Liability Derivatives	[1]	903,052	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		3,920	0
Liability Derivatives
Liability Derivatives		22,150	0
Interest rate swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	1,691	0
Interest rate swaps | Designated as Hedging Instrument | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	[1]	93,807	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]	107,668	0
Liability Derivatives
Liability Derivatives	[1]	292,372	17,619
Foreign currency forward contracts | Designated as Hedging Instrument | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	[1]	0	164,627
Fuel swaps | Designated as Hedging Instrument | Swaps | Other assets
Asset Derivatives
Asset Derivatives	[1]	0	0
Fuel swaps | Designated as Hedging Instrument | Swaps | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	0	0
Liability Derivatives
Liability Derivatives	[1]	239,715	227,512
Fuel swaps | Designated as Hedging Instrument | Swaps | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	[1]	277,158	270,254
Fuel swaps | Not Designated as Hedging Instrument | Swaps | Other assets
Asset Derivatives
Asset Derivatives		841	0
Fuel swaps | Not Designated as Hedging Instrument | Swaps | Derivative financial instruments
Asset Derivatives
Asset Derivatives		3,079	0
Liability Derivatives
Liability Derivatives		17,437	0
Fuel swaps | Not Designated as Hedging Instrument | Swaps | Other long-term Liabilities
Liability Derivatives
Liability Derivatives		$ 4,713	$ 0

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