Basis of Presentation - Computation of Basic and Diluted Earnings Per Share (Detail) - shares shares in Millions |
12 Months Ended | ||
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Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Earnings Per Share [Abstract] | |||
| Weighted average shares used in basic computations | 79.2 | 83.0 | 82.6 |
| Dilutive effect of exercise of equity grants outstanding | 3.7 | 3.1 | 2.7 |
| Weighted average shares used in diluted computations | 82.9 | 86.1 | 85.3 |
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- References No definition available.
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- Definition Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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