Basic and Diluted Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Basic and Diluted Earnings Per Share [Abstract]
Net Income	$ 263	$ 14
Weighted Average Number of Shares Outstanding, Basic (in shares)	177	176
Incremental Shares from Assumed Conversion of Dilutive Stock Options and Restricted Stock (in shares)	3	2
Weighted Average Number of Shares Outstanding, Diluted (in shares)	180	178
Earnings Per Share, Basic (in dollars per share)	$ 1.48	$ 0.08
Earnings Per Share, Diluted (in dollars per share)	$ 1.47	$ 0.08
Number of antidilutive stock options, shares of restricted stock and shares of common stock in rabbi trust excluded from calculation above	2	2

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) in the future that were not included in the computation of diluted EPS because to do so would increase EPS amounts or decrease loss per share amounts for the period presented.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

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

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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The amount of net income or loss for the period per each share of common stock and dilutive common stock equivalents outstanding during the reporting period.

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The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

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-Name Accounting Research Bulletin (ARB)

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-Appendix A

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The sum of dilutive potential common shares used in the calculation of the diluted per-share computation.

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The average number of shares issued and outstanding that are used in calculating diluted EPS, determined based on the timing of issuance of shares in the period.

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

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