Earnings Per 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
Numerator in millions [Abstract]
Net Income (Loss) Attributable to Parent	$ 27	$ 49	$ 118	$ 100
Denominator in thousands [Abstract]
Weighted Average Number of Shares Outstanding, Basic	75,342	75,295	75,329	75,267
Dilutive effect of unvested restricted stock units and employee stock purchase plan shares	16	16	16	15
Weighted Average Number of Shares Outstanding, Diluted	75,358	75,311	75,345	75,282
Earnings Per Share [Abstract]
Basic	$ 0.36	$ 0.65	$ 1.57	$ 1.32
Diluted	$ 0.36	$ 0.65	$ 1.57	$ 1.32

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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+ Details

- Definition

The amount of net income (loss) for 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.

+ References+ Details

- 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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-Appendix A

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-Glossary Other Comprehensive Income

-URI http://asc.fasb.org/extlink&oid=6519514

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Net Income

-URI http://asc.fasb.org/extlink&oid=6518256

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-Number 210

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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

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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-Glossary Weighted-Average Number of Common Shares Outstanding

-URI http://asc.fasb.org/extlink&oid=6528421

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+ Details