Stock-Based Compensation - Stock Option Activity (Detail)	9 Months Ended
Sep. 30, 2020 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, beginning of period \| shares	1,543,912
Options, Granted \| shares	127,388
Options, Exercised \| shares	(558,954)
Options, Forfeited \| shares	(8,908)
Options Outstanding, end of period \| shares	1,103,438
Weighted Average Exercise Price, Outstanding, beginning of period \| $ / shares	$ 30.03
Weighted Average Exercise Price, Granted \| $ / shares	58.88
Weighted Average Exercise Price, Exercised \| $ / shares	25.30
Weighted Average Exercise Price, Forfeited \| $ / shares	44.87
Weighted Average Exercise Price, Outstanding, end of period \| $ / shares	$ 35.64

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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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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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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