Schedule of Earnings Per Share Basic and Diluted (Detail) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share
Weighted-average shares outstanding used for the calculation of net income per share-basic	134.9	141.1	136.6	143.2
Common stock equivalents	1.7	1.5	1.7	1.6
Total shares used for the calculation of net income per share-diluted	136.6	142.6	138.3	144.8

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

+ References+ Details

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.

+ References

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

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 07-4

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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+ Details