Earnings Per Common Share (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Basic earnings (loss) per share:
Net income	$ 76	$ 240	$ 53	$ 475
Weighted average common shares outstanding (in thousands)	162,090	161,464	161,999	161,290
Basic earnings per share	$ 0.47	$ 1.49	$ 0.33	$ 2.94

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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-Glossary Net Income

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+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

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