Earnings Per Share - Numbers of Shares Used in Earnings Per Share Computation (Detail) - shares shares in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Basic:
Weighted average common shares outstanding	42,169	41,939
Diluted:
Dilutive effect of stock appreciation rights, restricted stock, restricted stock units and shares held in rabbi trust	130	293
Total weighted average diluted shares outstanding	42,299	42,232
Anti-dilutive shares excluded from the diluted earnings per share calculation	115	9

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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- Definition

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

+ 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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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