Changes in Accumulated Other Comprehensive (Loss) Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassifications out of accumulated other comprehensive loss
Interest expense, net of interest capitalized	$ (73,233)	$ (82,610)	$ (230,182)	$ (226,803)
Depreciation and amortization expenses	(240,150)	(229,328)	(710,836)	(661,712)
Other expense	15,354	(41,706)	(99,613)	(158,061)
Other operating	(253,892)	(260,718)	(780,257)	(857,161)
Fuel	(160,752)	(178,772)	(508,914)	(531,283)
Net income	752,842	693,257	1,337,094	1,022,302
Amounts reclassified from accumulated other comprehensive income (loss)	(43,605)	(80,908)	(152,169)	(265,147)
Loss on cash flow derivative hedges:
Reclassifications out of accumulated other comprehensive loss
Amounts reclassified from accumulated other comprehensive income (loss)			(151,319)	(263,774)
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	(43,312)	(80,623)	(151,319)	(263,774)
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	(7,860)	(11,953)	(24,580)	(32,019)
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	(2,710)	(2,710)	(8,130)	(5,408)
Other expense	(1,512)	(3,465)	(9,187)	(10,206)
Other operating	0	0	0	(207)
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	(602)	(601)	(1,806)	(1,806)
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	1,758	2,760	6,533	9,356
Fuel	(32,386)	(64,654)	(114,149)	(223,484)
Actuarial loss
Reclassifications out of accumulated other comprehensive loss
Amounts reclassified from accumulated other comprehensive income (loss)	(293)	(285)	(850)	(1,373)
Amortization of defined benefit plans:
Reclassifications out of accumulated other comprehensive loss
Amounts reclassified from accumulated other comprehensive income (loss)	$ (293)	$ (285)	$ (850)	$ (1,373)