Changes in Accumulated Other Comprehensive Income (Loss) (Reclassifications) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net of interest capitalized	$ (307,370)	$ (277,725)	$ (258,299)
Depreciation and amortization expenses	(894,915)	(827,008)	(772,445)
Other income (expense)	35,653	24,445	(18,602)
Other indirect operating expenses	(1,090,064)	(1,007,926)	(1,077,584)
Fuel	(713,676)	(795,801)	(947,391)
Reclassification out of accumulated other comprehensive income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI	(338,391)	(289,131)	(53,465)
Reclassification out of accumulated other comprehensive income (loss) | Loss on cash flow derivative hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI	(337,250)	(291,624)	(49,744)
Reclassification out of accumulated other comprehensive income (loss) | 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	0	0	(261)
Reclassification out of accumulated other comprehensive income (loss) | Loss on cash flow derivative hedges: | Interest rate swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net of interest capitalized	(41,480)	(36,401)	(15,264)
Reclassification out of accumulated other comprehensive income (loss) | Loss on cash flow derivative hedges: | Foreign currency forward contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net of interest capitalized	0	0	(57)
Depreciation and amortization expenses	(8,114)	(2,871)	(1,887)
Other income (expense)	(14,342)	7,580	(4,291)
Other indirect operating expenses	(207)	0	0
Reclassification out of accumulated other comprehensive income (loss) | Loss on cash flow derivative hedges: | Collars
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Depreciation and amortization expenses	(2,408)	(1,605)	0
Reclassification out of accumulated other comprehensive income (loss) | Loss on cash flow derivative hedges: | Fuel contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)	13,685	(9,583)	0
Fuel	(284,384)	(248,744)	(27,984)
Reclassification out of accumulated other comprehensive income (loss) | Actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI	(1,141)	(1,414)	(888)
Reclassification out of accumulated other comprehensive income (loss) | Prior service costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI	0	(293)	(836)
Reclassification out of accumulated other comprehensive income (loss) | Amortization of defined benefit plans:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI	(1,141)	(1,707)	(1,724)
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)	$ 0	$ 4,200	$ (1,997)