Changes in Accumulated Other Comprehensive Loss (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Amortization of unrecognized net periodic benefit costs:
Depreciation and amortization	$ 186,184	$ 180,514	$ 375,548	$ 359,906
Other income (expense)	(5,119)	(16,424)	(8,090)	(18,515)
Interest expense, net of interest capitalized	86,877	89,106	177,059	181,772
Fuel	232,471	237,961	474,123	466,955
Net Income (Loss)	24,747	(3,653)	100,973	43,311
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income
Amortization of unrecognized net periodic benefit costs:
Net Income (Loss)	6,540		21,810
Gain (loss) on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated OCI into Income
Amortization of unrecognized net periodic benefit costs:
Net Income (Loss)	7,834		23,104
Gain (loss) on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated OCI into Income | Cross currency swaps
Amortization of unrecognized net periodic benefit costs:
Interest expense, net of interest capitalized	(880)		(1,751)
Gain (loss) on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated OCI into Income | Foreign currency forward contracts
Amortization of unrecognized net periodic benefit costs:
Depreciation and amortization	(450)		(899)
Other income (expense)	(239)		(477)
Interest expense, net of interest capitalized	(5)		(5)
Gain (loss) on cash flow derivative hedges: | Amount of Gain (Loss) Reclassified from Accumulated OCI into Income | Fuel swaps
Amortization of unrecognized net periodic benefit costs:
Fuel	9,408		26,236
Amortization of defined benefit plans | Amount of Gain (Loss) Reclassified from Accumulated OCI into Income
Amortization of unrecognized net periodic benefit costs:
Actuarial loss	(876)		(876)
Prior service costs	(418)		(418)
Net Income (Loss)	$ (1,294)		$ (1,294)