Summary of Significant Accounting Policies (Earnings Per Share) (Details) (USD $) In Millions, except 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
Basic earnings per share - continuing operations:
Income from continuing operations attributable to common shareholders, net of tax													$ (34)		$ 1,252		$ 856
Participating securities dividends													0		(5)		(6)
Income from continuing operations available to common shareholders													(34)		1,247		850
Weighted average common shares outstanding (in shares)													326,000,000		326,000,000		326,000,000
Basic earnings per share - continuing operations (in dollars per share)	$ (2.57)		$ 1.31		$ 0.54		$ 0.62		$ 0.51	$ 1.57	$ 1.05	$ 0.70	$ (0.10)		$ 3.83		$ 2.61
Diluted earnings per share - continuing operations:
Income from continuing operations available to common shareholders													(34)		1,247		850
Income impact of assumed conversions													0	[1]	5		1
Income from continuing operations available to common shareholders and assumed conversions													$ (34)		$ 1,252		$ 851
Weighted average common shares outstanding (in shares)													326,000,000		326,000,000		326,000,000
Incremental shares from assumed conversions (in shares)													0	[1]	3,000,000	[2]	1,000,000	[2]
Adjusted weighted average shares - diluted (in shares)													326,000,000		329,000,000		327,000,000
Diluted earnings per share - continuing operations (in dollars per share)	$ (2.57)	[3]	$ 1.30	[3]	$ 0.54	[3]	$ 0.62	[3]	$ 0.51	$ 1.57	$ 1.05	$ 0.70	$ (0.10)	[3]	$ 3.81		$ 2.60
Stock-Based Compensation Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share
Stock-based compensation awards excluded from the computation of diluted earnings per share (in shares)															5,981,090		8,547,090

[1] Due to a loss for the period, there are no incremental shares in the computation because such shares would be considered antidilutive.

[2] Stock-based compensation awards to purchase 5,981,090, and 8,547,090 shares of common stock for the years ended December 31, 2010 and 2009, respectively, were outstanding, but were not included in the computation of diluted earnings per share because the exercise price of the awards was greater than the average market price of the common shares during the respective periods and, therefore, the effect would have been antidilutive.

[3] Due to a loss for the three months and year ended December 31, 2011, there are no incremental shares in the diluted computation because such shares would be considered antidilutive.