Earnings Per Share - (Additional Information) (Detail) - $ / shares	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Stock options, outstanding	1,027,831		998,226
Stock options, weighted average exercise price	$ 28.53		$ 27.54
Common stock excluded from calculation of diluted earnings per share	210,388	593,874
Option To Purchase Common Stock [Member]
Stock options, outstanding	1,027,831	1,109,353
Stock options, weighted average exercise price	$ 28.53	$ 25.34
Restricted Stock Units (RSUs) [Member]
Restricted stock units, outstanding	680,549	703,076	705,413

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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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