Changes in Accumulated Other Comprehensive Income (Loss) (Reclassifications) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									$ 209,119	$ 177,713	$ 324,456
Interest expense, net of interest capitalized									(277,725)	(258,299)	(332,422)
Depreciation and amortization expenses									(827,008)	(772,445)	(754,711)
Fuel									(795,801)	(947,391)	(924,414)
Net income	$ 206,799	$ 228,787	$ 184,967	$ 45,230	$ 109,768	$ 490,248	$ 137,673	$ 26,457	665,783	764,146	473,692
Reclassification out of accumulated other comprehensive income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income									(289,131)	(53,465)	57,655
Reclassification out of accumulated other comprehensive income (loss) | (Loss) gain on cash flow derivative hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income									(291,624)	(49,744)	60,244
Reclassification out of accumulated other comprehensive income (loss) | (Loss) gain on cash flow derivative hedges: | Cross currency swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net of interest capitalized									0	(261)	(3,531)
Reclassification out of accumulated other comprehensive income (loss) | (Loss) gain on cash flow derivative hedges: | Foreign currency forward contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									7,580	(4,291)	27,423
Interest expense, net of interest capitalized									0	(57)	(440)
Depreciation and amortization expenses									(2,871)	(1,887)	(1,797)
Reclassification out of accumulated other comprehensive income (loss) | (Loss) gain on cash flow derivative hedges: | Interest rate swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net of interest capitalized									(36,401)	(15,264)	(9,355)
Reclassification out of accumulated other comprehensive income (loss) | (Loss) gain on cash flow derivative hedges: | Fuel contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									(9,583)	0	0
Fuel									(248,744)	(27,984)	47,944
Reclassification out of accumulated other comprehensive income (loss) | (Loss) gain on cash flow derivative hedges: | Collars
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Depreciation and amortization expenses									(1,605)	0	0
Reclassification out of accumulated other comprehensive income (loss) | Amortization of defined benefit plans:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial loss									(1,414)	(888)	(1,753)
Prior service costs									(293)	(836)	(836)
Net income									(1,707)	(1,724)	(2,589)
Reclassification out of accumulated other comprehensive income (loss) | Foreign currency translation adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									$ (4,200)	$ (1,997)	$ 0