Fair Value Measurements and Derivative Instruments - Designated Cash Flow Hedges (Details) - Cash flow hedge - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss) on Derivative (Effective Portion)	$ 186,935	$ 14,913	$ 230,341	$ (9,150)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	(43,312)	(80,623)	(151,319)	(263,774)
Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	3,426	82	1,114	(5,158)
Interest rate swaps
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss) on Derivative (Effective Portion)	(3,154)	6,598	(24,703)	(126,505)
Interest rate swaps | Interest expense, net of interest capitalized
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	(7,860)	(11,953)	(24,580)	(32,019)
Interest rate swaps | Other expense
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	90	0	(1,152)
Foreign currency forward contracts
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss) on Derivative (Effective Portion)	122,211	11,405	221,861	22,715
Foreign currency forward contracts | Depreciation and amortization expenses
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	(2,710)	(2,710)	(8,130)	(5,408)
Foreign currency forward contracts | Other expense
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	(1,512)	(3,465)	(9,187)	(10,206)
Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	75	0	100	(57)
Foreign currency forward contracts | Other Operating Expenses
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	0	0	0	(207)
Foreign currency collar options | Depreciation and amortization expenses
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	(602)	(601)	(1,806)	(1,806)
Fuel swaps
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss) on Derivative (Effective Portion)	67,878	(3,090)	33,183	94,640
Fuel swaps | Other expense
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	1,758	2,760	6,533	9,356
Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	3,351	(8)	1,014	(3,949)
Fuel swaps | Fuel cost
Effect of derivative instruments involved in hedging on the consolidated financial statements
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Effective Portion)	$ (32,386)	$ (64,654)	$ (114,149)	$ (223,484)