Stock-Based Compensation - Summary of Stock Option and Other Equity Award Activity Under Plans (Details)	3 Months Ended
Mar. 31, 2018 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Subject to Outstanding Options and Awards, Beginning Balance \| shares	2,964,549
Shares Subject to Outstanding Options and Awards, granted \| shares	991,932
Shares Subject to Outstanding Options and Awards, exercised \| shares	(110,961)
Shares Subject to Outstanding Options and Awards, canceled \| shares	(52,156)
Shares Subject to Outstanding Options and Awards, Ending Balance \| shares	3,793,364
Weighted Average Exercise Price per Share, Beginning Balance \| $ / shares	$ 11.54
Weighted Average Exercise Price per Share, granted \| $ / shares	52.05
Weighted Average Exercise Price per Share, exercised \| $ / shares	7.26
Weighted Average Exercise Price per Share, canceled \| $ / shares	19.13
Weighted Average Exercise Price per Share, Ending Balance \| $ / shares	$ 22.15

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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
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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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-Publisher FASB
-Name Accounting Standards Codification
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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