Changes in Accumulated Other Comprehensive (Loss) Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassifications out of accumulated other comprehensive loss
Interest expense, net of interest capitalized	$ (67,878)	$ (80,317)
Depreciation and amortization expenses	(240,230)	(235,749)
Other expense	55,493	64,796
Fuel	(160,341)	(177,414)
Net income	218,653	214,726
Amounts reclassified from accumulated other comprehensive income (loss)	(15,257)	(53,653)
Loss on cash flow derivative hedges
Reclassifications out of accumulated other comprehensive loss
Amounts reclassified from accumulated other comprehensive income (loss)	(14,914)	(53,390)
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	(14,914)	(53,390)
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	(6,838)	(8,857)
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
Depreciation and amortization expenses	(3,312)	(2,710)
Other expense	42	(3,570)
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	0	(602)
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
Other expense	325	2,277
Fuel	(5,131)	(39,928)
Actuarial loss
Reclassifications out of accumulated other comprehensive loss
Amounts reclassified from accumulated other comprehensive income (loss)	(343)	(263)
Amortization of defined benefit plans
Reclassifications out of accumulated other comprehensive loss
Amounts reclassified from accumulated other comprehensive income (loss)	$ (343)	$ (263)