Changes in Accumulated Other Comprehensive (Loss) Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassifications out of accumulated other comprehensive loss
Interest expense, net of interest capitalized	$ (76,620)	$ (65,260)	$ (146,779)	$ (133,831)
Depreciation and amortization expenses	(206,468)	(192,880)	(406,936)	(386,615)
Other income (expense)	76,330	57,914	136,782	128,923
Fuel	(202,565)	(242,804)	(407,841)	(487,263)
Net income	184,967	137,673	230,197	164,130
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income
Reclassifications out of accumulated other comprehensive loss
Net income	(64,175)	(5,310)	(126,170)	(13,307)
Loss on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income
Reclassifications out of accumulated other comprehensive loss
Net income	(63,737)	(2,882)	(125,170)	(10,447)
Loss on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income | Cross currency swaps
Reclassifications out of accumulated other comprehensive loss
Interest expense, net of interest capitalized	0	0	0	(261)
Loss on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income | Interest rate swaps
Reclassifications out of accumulated other comprehensive loss
Interest expense, net of interest capitalized	(9,962)	(3,078)	(16,748)	(6,206)
Loss on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income | Foreign currency forward contracts
Reclassifications out of accumulated other comprehensive loss
Interest expense, net of interest capitalized	0	0	0	(57)
Depreciation and amortization expenses	(685)	(450)	(1,402)	(899)
Other income (expense)	239	(238)	(477)	(3,814)
Loss on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income | Foreign currency collar options
Reclassifications out of accumulated other comprehensive loss
Depreciation and amortization expenses	(435)	0	(435)	0
Loss on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income | Fuel swaps
Reclassifications out of accumulated other comprehensive loss
Fuel	(52,416)	884	(106,108)	790
Amortization of defined benefit plans: | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income
Reclassifications out of accumulated other comprehensive loss
Actuarial loss	(354)	(222)	(707)	(445)
Prior service costs	(84)	(209)	(293)	(418)
Net income	(438)	(431)	(1,000)	(863)
Accumulated Translation Adjustment | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income
Reclassifications out of accumulated other comprehensive loss
Other income (expense)	$ 0	$ 1,997	$ 0	$ 1,997