Earnings Per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) - shares shares in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share Basic And Diluted [Abstract]
Basic weighted average shares outstanding	36,950	36,853	36,952	36,852
Dilutive effect of stock options and restricted stock	912	1,224	922	1,243
Diluted weighted average shares outstanding	37,862	38,077	37,874	38,095

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.

+ References

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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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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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