Changes in Accumulated Other Comprehensive Income (Loss) (Reclassifications) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									$ (177,713)	$ (324,456)	$ (384,823)
Interest expense, net of interest capitalized									(258,299)	(332,422)	(355,785)
Depreciation and amortization expenses									(772,445)	(754,711)	(730,493)
Fuel									(947,391)	(924,414)	(909,691)
Net income	109,768	490,248	137,673	26,457	7,018	365,701	24,747	76,226	764,146	473,692	18,287
Reclassification out of accumulated other comprehensive income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income									(38,201)	67,010
Reclassification out of accumulated other comprehensive income (loss) | Gain (loss) on cash flow derivative hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income									(34,480)	69,599
Reclassification out of accumulated other comprehensive income (loss) | Gain (loss) on cash flow derivative hedges: | Cross currency swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net of interest capitalized									(261)	(3,531)
Reclassification out of accumulated other comprehensive income (loss) | Gain (loss) on cash flow derivative hedges: | Foreign currency forward contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									(4,291)	27,423
Interest expense, net of interest capitalized									(57)	(440)
Depreciation and amortization expenses									(1,887)	(1,797)
Reclassification out of accumulated other comprehensive income (loss) | Gain (loss) on cash flow derivative hedges: | Fuel contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Fuel									(27,984)	47,944
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									(888)	(1,753)
Prior service costs									(836)	(836)
Net income									(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)									$ (1,997)	$ 0