Earnings Per Share (Detail) - shares	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average number of shares for calculation of basic EPS	32,838,636	36,103,520	33,282,584	36,364,380
Stock options, restricted stock awards and restricted stock units under equity incentive plans	94,043	344,642	135,971	105,379
Weighted average number of shares for calculation of diluted EPS	32,932,679	36,448,162	33,418,555	36,469,759
Stock options under equity incentive plans
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Stock options outstanding for equity incentive plans	441,435	12,000	441,435	1,359,250

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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.

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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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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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