Changes in Accumulated Other Comprehensive (Loss) Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassifications out of accumulated other comprehensive loss
Interest expense, net of interest capitalized	$ (82,610)	$ (66,819)	$ (226,803)	$ (213,598)
Depreciation and amortization expenses	(229,328)	(210,742)	(661,712)	(617,678)
Other income	41,706	29,218	158,061	166,000
Other operating	(260,718)	(259,057)	(857,161)	(777,291)
Fuel	(178,772)	(199,848)	(531,283)	(607,689)
Net income	693,257	228,787	1,022,302	458,984
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income
Reclassifications out of accumulated other comprehensive loss
Net income	(80,908)	(78,164)	(265,147)	(204,332)
(Loss) gain 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	(80,623)	(77,810)	(263,774)	(202,978)
(Loss) gain 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	(11,953)	(10,276)	(32,019)	(27,024)
(Loss) gain 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	(2,710)	(752)	(5,408)	(2,153)
Other income	(3,465)	(239)	(10,206)	(715)
Other operating	0	0	(207)	0
(Loss) gain 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	(601)	(568)	(1,806)	(1,003)
(Loss) gain 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 income	2,760	0	9,356	0
Fuel	(64,654)	(65,975)	(223,484)	(172,083)
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	(285)	(354)	(1,373)	(1,061)
Prior service costs	0	0	0	(293)
Net income	$ (285)	$ (354)	$ (1,373)	$ (1,354)