Background and Basis of Presentation (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended
Jan. 31, 2011	Jun. 30, 2011
Background and Basis of Presentation
Equity method investment, ownership percentage		27.10%
Planned share repurchase program	$ 1,000,000,000
Shares repurchased during period		22.8
Shares repurchased during period, value		$ 616,000,000
Average price of repurchased shares, per share		$ 27.07

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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