Stock-Based Awards - Summary of Stock Option Activity (Details)	6 Months Ended
Jun. 30, 2020 $ / shares shares
Number of Options
Beginning balance (in shares) \| shares	11,640,734
Granted (in shares) \| shares	3,244,298
Exercised (in shares) \| shares	(461,968)
Forfeited (in shares) \| shares	(232,093)
Ending balance (in shares) \| shares	14,190,971
Vested and expected to vest (in shares) \| shares	12,446,239
Exercisable (in shares) \| shares	5,318,846
Weighted- Average Exercise Price
Beginning balance (usd per share) \| $ / shares	$ 12.96
Granted (usd per share) \| $ / shares	24.78
Exercised (usd per share) \| $ / shares	7.67
Forfeited (usd per share) \| $ / shares	19.08
Ending balance (usd per share) \| $ / shares	15.74
Vested and expected to vest (usd per share) \| $ / shares	17.85
Exercisable (usd per share) \| $ / shares	$ 13.52

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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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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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 exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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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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