Calculation of Dilutive Stock Awards (Detail) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares outstanding	75,901	75,927	75,831	75,949
Weighted average shares outstanding assuming dilution	76,589	76,979	76,579	77,006
Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of dilutive securities	471	843	506	859
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of dilutive securities	202	204	229	193
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of dilutive securities	15	5	13	5

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

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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 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Weighted-Average Number of Common Shares Outstanding

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

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