Hedging Activities (Description of Derivative Instruments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Nonoperating income (expense)	$ (266)	$ (170)	$ (511)	$ (327)
Second Half Of 2011 [Member] | Maximum [Member]
Percentage of Expected Consumption	51.00%		51.00%
Second Half Of 2011 [Member] | Maximum [Member] | Aircraft Fuel Swaps [Member]
Percentage of Expected Consumption	1.00%		1.00%
Weighted Average Price (per gallon)	3.14		3.14
Second Half Of 2011 [Member] | Maximum [Member] | Aircraft Fuel Call Options [Member]
Percentage of Expected Consumption	4.00%		4.00%
Weighted Average Price (per gallon)	3.15		3.15
Second Half Of 2011 [Member] | Maximum [Member] | Heating Oil Swaps [Member]
Percentage of Expected Consumption	3.00%		3.00%
Weighted Average Price (per gallon)	2.24		2.24
Second Half Of 2011 [Member] | Maximum [Member] | Heating Oil Call Options [Member]
Percentage of Expected Consumption	4.00%		4.00%
Weighted Average Price (per gallon)	2.41		2.41
Second Half Of 2011 [Member] | Maximum [Member] | Heating Oil Collars [Member]
Percentage of Expected Consumption	15.00%		15.00%
Weighted Average Price (per gallon)	3.32		3.32
Second Half Of 2011 [Member] | Maximum [Member] | WTI Crude Oil Swaps [Member]
Percentage of Expected Consumption	11.00%		11.00%
Weighted Average Price (per gallon)	2.17		2.17
Second Half Of 2011 [Member] | Maximum [Member] | WTI Crude Oil Call Options [Member]
Percentage of Expected Consumption	13.00%		13.00%
Weighted Average Price (per gallon)	2.32		2.32
Second Half Of 2011 [Member] | Minimum [Member]
Percentage of Expected Consumption	30.00%		30.00%
Weighted Average Price (per gallon)
Second Half Of 2011 [Member] | Minimum [Member] | Aircraft Fuel Swaps [Member]
Percentage of Expected Consumption	1.00%		1.00%
Weighted Average Price (per gallon)	3.14		3.14
Second Half Of 2011 [Member] | Minimum [Member] | Aircraft Fuel Call Options [Member]
Percentage of Expected Consumption
Weighted Average Price (per gallon)
Second Half Of 2011 [Member] | Minimum [Member] | Heating Oil Swaps [Member]
Percentage of Expected Consumption	3.00%		3.00%
Weighted Average Price (per gallon)	2.24		2.24
Second Half Of 2011 [Member] | Minimum [Member] | Heating Oil Call Options [Member]
Percentage of Expected Consumption
Weighted Average Price (per gallon)
Second Half Of 2011 [Member] | Minimum [Member] | Heating Oil Collars [Member]
Percentage of Expected Consumption	15.00%		15.00%
Weighted Average Price (per gallon)	2.65		2.65
Second Half Of 2011 [Member] | Minimum [Member] | WTI Crude Oil Swaps [Member]
Percentage of Expected Consumption	11.00%		11.00%
Weighted Average Price (per gallon)	2.17		2.17
Second Half Of 2011 [Member] | Minimum [Member] | WTI Crude Oil Call Options [Member]
Percentage of Expected Consumption
Weighted Average Price (per gallon)
First Half Of 2012 [Member]
Hedging percentage of fuel consumption			13.00%
Aircraft Fuel Hedges [Member]
Nonoperating income (expense)	$ (34)		$ (31)