Reconciliation of Average Number of Common Shares Outstanding to Average Number of Diluted Shares Outstanding (Detail)	3 Months Ended	9 Months Ended
Sep. 29, 2012	Sep. 24, 2011	Sep. 29, 2012	Sep. 24, 2011
Earnings Per Share Disclosure [Line Items]
Average number of common shares outstanding	46,614,000	47,358,000	46,775,000	47,670,000
Incremental shares from assumed exercises of stock options	118,000	29,000	189,000	65,000
Average number of common shares and common share equivalents outstanding	46,732,000	47,387,000	46,964,000	47,735,000

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

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 7: http://www.xbrl.org/2003/role/presentationRef

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+ Details