Maximum number of shares that may be added annually to the plan on the first day of the fiscal year.

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Maximum number of shares that may be cumulatively issued annually in accordance with the plan, as a percentage of outstanding capital stock.

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Aggregate number of common shares reserved for future issuance.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of additional shares authorized for issuance under share-based payment arrangement.

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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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

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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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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Stock Options - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2021	Jun. 30, 2017	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Share-based awards
Number of shares outstanding (in shares)			8,342,429	6,112,948
Options granted (in shares)			3,308,220
Weighted-average grant date fair value of options granted (in dollars per share)			$ 11.71	$ 7.99	$ 2.47
Intrinsic value of options exercised			$ 4,299	$ 11,147	$ 202
Cash received from the exercise of stock options (in dollars)			$ 1,837	$ 3,138	$ 175
Expected dividend yield			0.00%	0.00%	0.00%
Number of shares reserved for future issuance (in shares)			9,199,512	6,869,189
Employee stock purchase plan
Share-based awards
Number of shares available for future issuance (in shares)			566,565
Number of shares reserved for future issuance (in shares)						225,000
Purchase of common stock under ESPP (in shares)			78,253	80,267
Stock options
Share-based awards
Unrecognized stock compensation cost			$ 38,958
Weighted-average amortization period of unrecognized stock compensation cost			2 years 7 months 6 days
Unvested restricted stock units
Share-based awards
Fair value of RSUs vested			$ 5,790	$ 0	$ 0
Unrecognized stock compensation cost			$ 9,929
Weighted-average amortization period of unrecognized stock compensation cost			2 years 9 months 18 days
Unvested restricted stock units \| Maximum
Share-based awards
Vesting period			4 years
Unvested restricted stock units \| Minimum
Share-based awards
Vesting period			1 year
2007 Plan
Share-based awards
Number of shares outstanding (in shares)		3,141,625
2017 Plan
Share-based awards
Number of shares authorized (in shares)		2,255,000
Cumulative annual increase in number of shares issuable, percentage		4.00%
Additional shares authorized (in shares)	2,753,651
Number of shares available for future issuance (in shares)			1,308,183
Options granted (in shares)			2,870,720
2017 Plan \| Maximum
Share-based awards
Expiration period			10 years
2017 Plan \| Stock options
Share-based awards
Vesting period			4 years
2017 Plan \| Unvested restricted stock units
Share-based awards
RSUs granted (in shares)			715,716
Inducement Award Program
Share-based awards
Number of shares outstanding (in shares)			757,500
2017 ESPP \| Employee stock purchase plan
Share-based awards
Cumulative annual increase in number of shares issuable, percentage						1.00%
2017 ESPP \| Employee stock purchase plan \| Common Stock
Share-based awards
Maximum annual increase (in shares)						450,000
2017 ESPP \| Employee stock purchase plan \| Maximum
Share-based awards
Number of shares authorized (in shares)						4,725,000