Stock Based Compensation - Summary of PSO Activities (Detail) - Performance Stock Options (PSOs) - 2013 Equity Incentive Plan	6 Months Ended
Jun. 30, 2019 $ / shares shares
Shares Subject to Outstanding PSOs
Beginning balance \| shares	143,335
Options granted \| shares	490,986
Options exercised \| shares	(26,667)
Options canceled \| shares	(11,250)
Ending balance \| shares	596,404
Weighted-Average Exercise Price Per Share
Beginning balance \| $ / shares	$ 23.76
Options granted \| $ / shares	33.29
Options exercised \| $ / shares	23.76
Options canceled \| $ / shares	33.29
Ending balance \| $ / shares	$ 31.43

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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-Publisher FASB
-Name Accounting Standards Codification
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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