Calculation Of Net Income Per Share (Weighted-Average Shares Used In Calculation Of Basic And Diluted EPS) (Details) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Abstract]
Weighted-average number of common shares outstanding	156,953	165,408	177,534
Stock options	174	309	428
Unvested restricted stock units	763	736	873
Conversion spread related to Convertible Debentures	5,944	416	0
Employee stock purchase plan	75	18	130
Shares used to compute diluted net income per share	163,909	166,887	178,965

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of equity unit purchase agreements using the treasury stock method.

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Nonvested equity-based payment awards that contain forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) that result in incremental common shares.

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- 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.

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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

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

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