Fair Value Measurements and Derivative Instruments (Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Asset Derivatives
Asset Derivatives	$ 134,574	$ 63,981
Liability Derivatives
Liability Derivatives	1,044,292	767,635
Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	93,996	63,981
Liability Derivatives
Liability Derivatives	1,020,774	767,635
Designated as Hedging Instrument | Collars | Derivative Financial Instruments
Liability Derivatives
Liability Derivatives	0	21,855
Not Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	40,578	0
Liability Derivatives
Liability Derivatives	23,518	0
Interest rate swaps | Designated as Hedging Instrument | Other Assets
Asset Derivatives
Asset Derivatives	0	0
Interest rate swaps | Designated as Hedging Instrument | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	67,371	65,768
Foreign currency forward contracts | Designated as Hedging Instrument | Other Assets
Asset Derivatives
Asset Derivatives	0	63,981
Foreign currency forward contracts | Designated as Hedging Instrument | Derivative Financial Instruments
Asset Derivatives
Asset Derivatives	93,996	0
Liability Derivatives
Liability Derivatives	320,873	17,619
Foreign currency forward contracts | Designated as Hedging Instrument | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	0	164,627
Foreign currency forward contracts | Not Designated as Hedging Instrument
Liability Derivatives
Liability Derivatives	0	0
Foreign currency forward contracts | Not Designated as Hedging Instrument | Derivative Financial Instruments
Asset Derivatives
Asset Derivatives	32,339	0
Fuel contracts | Designated as Hedging Instrument | Fuel Swaps | Other Assets
Asset Derivatives
Asset Derivatives	0	0
Fuel contracts | Designated as Hedging Instrument | Fuel Swaps | Derivative Financial Instruments
Asset Derivatives
Asset Derivatives	0	0
Liability Derivatives
Liability Derivatives	307,475	227,512
Fuel contracts | Designated as Hedging Instrument | Fuel Swaps | Other long-term Liabilities
Liability Derivatives
Liability Derivatives	325,055	270,254
Fuel contracts | Not Designated as Hedging Instrument | Fuel Swaps | Derivative Financial Instruments
Asset Derivatives
Asset Derivatives	8,239	0
Liability Derivatives
Liability Derivatives	$ 23,518	$ 0