Earnings Per Share (Details) (USD $) In Millions, except Per Share data	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Basic and diluted earnings per share [Abstract]
Income from continuing operations	$ 71	$ 12	$ 365	$ 382
Weighted average common shares outstanding	184.4	182.5	184.0	182.2
Add: Weighted average restricted stock awards outstanding	1.1	1.6	1.2	1.6
Basic weighted average common shares outstanding	185.5	184.1	185.2	183.8
Add: Dilutive impact of stock options	1.0	1.2	1.4	1.4
Diluted weighted average common shares outstanding	186.5	185.3	186.6	185.2
Basic earnings per share from continuing operations	$ 0.38	$ 0.07	$ 1.97	$ 2.08
Diluted earnings per share from continuing operations	$ 0.38	$ 0.07	$ 1.96	$ 2.06

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

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- Definition

The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

This element represents nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). Basic and dilutive earnings per share are generally disclosed for such shares using the two-class method.

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-Glossary Participating Security

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+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References+ Details

- Definition

This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).

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- 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.

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-Glossary Weighted-Average Number of Common Shares Outstanding

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