Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Selected Quarterly Financial Information [Abstract]
Revenues	$ 8,722	$ 8,333	$ 8,311	$ 8,313	$ 8,301		$ 8,152		$ 8,025		$ 8,085		$ 33,679	$ 32,563	$ 32,260
Operating Income (Loss)	(438)	208	79	259	(139)		(213)		(63)		(180)		108	(595)	(1,398)
Net loss	$ (1,303)	$ (301)	$ (847)	$ (439)	$ (929)		$ (911)		$ (760)		$ (865)		$ (2,890)	$ (3,465)	$ (2,436)
Basic and diluted loss per common share	$ (0.43)	$ (0.1)	$ (0.28)	$ (0.15)	$ (0.31)	[1]	$ (0.30)	[1]	$ (0.25)	[1]	$ (0.29)	[1]	$ (0.96)	$ (1.16)	$ (0.84)

[1] (1)The sum of the quarterly earnings per share amounts may not equal the annual amounts because of the changes in the weighted average number of shares outstanding during the year.