Stock Incentive Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock incentive plans
Weighted average fair value of options to purchase common stock granted (in dollars per share)	$ 11.07	$ 3.62	$ 4.49
Intrinsic value of stock options exercised (in dollars)	$ 31,300	$ 4,900	$ 700
Weighted average grant date fair value (in dollars per share)	$ 21.90	$ 6.17
Intrinsic value of stock options outstanding	$ 77,453
Options outstanding (in shares)	5,562,484	6,235,258
Common Stock
Stock incentive plans
Share price (in dollars per share)	$ 27.92	$ 12.58
Non Employee Stock Option
Stock incentive plans
Options outstanding (in shares)	0
Employee stock options
Stock incentive plans
Total estimated grant date fair value of options to purchase common stock vested (in dollars)	$ 4,400	$ 4,100	$ 3,100
Restricted stock units
Stock incentive plans
Intrinsic value of stock options outstanding	$ 2,720	$ 184

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Number of options outstanding, including both vested and non-vested options.

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Amount by which current fair value of underlying stock exceeds exercise price of 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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Price of a single share of a number of saleable stocks of a company.

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