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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The number of grants made during the period for share options (or share units) and for other than stock (or unit) options, including but not limited to, restricted stock options (or units). This amount does not include options granted as part of an inducement award.

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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 nonvested award under share-based payment arrangement. Excludes share and unit options.

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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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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-based compensation - Narrative (Details) - USD ($)		1 Months Ended	12 Months Ended
	Jan. 01, 2022	Jun. 30, 2017	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2017	Feb. 28, 2022
Share-based awards
Number of shares outstanding (in shares)			10,051,283	8,342,429
Weighted-average grant date fair value of options granted (in dollars per share)			$ 3.97	$ 11.71	$ 7.99
Intrinsic value of options exercised			$ 1,500,000	$ 4,300,000	$ 11,100,000
Cash received from the exercise of stock options (in dollars)			$ 1,331,000	$ 1,837,000	$ 3,138,000
Expected dividend yield			0.00%	0.00%	0.00%
Number of shares reserved for future issuance (in shares)			11,944,664	9,199,512
Stock options
Share-based awards
Unrecognized stock compensation cost, unvested stock options			$ 30,400,000
Weighted-average amortization period of unrecognized stock compensation cost			2 years
Unvested restricted stock units
Share-based awards
Fair value of RSUs vested			$ 1,500,000	$ 5,800,000	$ 0
Unrecognized stock compensation cost, unvested RSUs			$ 11,600,000
Weighted-average amortization period of unrecognized stock compensation cost			2 years 7 months 6 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)	2,948,362
Number of shares available for future issuance (in shares)			1,501,829
Grants in period (in shares)			3,541,558
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)			1,460,924
Inducement Award Program
Share-based awards
Number of shares authorized (in shares)							2,000,000
Number of shares available for future issuance (in shares)			1,342,175
Grants in period (in shares)			713,025
2017 ESPP \| Employee stock purchase plan
Share-based awards
Additional shares authorized (in shares)	0
Number of shares available for future issuance (in shares)			295,791
Number of shares reserved for future issuance (in shares)						225,000
Purchase of common stock under ESPP (in shares)			270,774	78,253
2017 ESPP \| Employee stock purchase plan \| Common Stock
Share-based awards
Cumulative annual increase in number of shares issuable, percentage						1.00%
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
Prior to Inducement Award Program
Share-based awards
Number of shares authorized (in shares)			757,500