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Stock-based compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jan. 01, 2023	Jun. 30, 2017	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2017	Feb. 28, 2022
Share-based awards
Weighted-average grant date fair value of options granted (in dollars per share)			$ 3.82	$ 3.97	$ 11.71
Intrinsic value of options exercised			$ 300	$ 1,500	$ 4,300
Cash received from the exercise of stock options (in dollars)			$ 427	$ 1,331	$ 1,837
Number of shares reserved for future issuance (in shares)			14,736,953	11,944,664
Expected dividend yield			0.00%	0.00%	0.00%
Stock options
Share-based awards
Unrecognized stock compensation cost, unvested stock options			$ 14,800
Weighted-average amortization period of unrecognized stock compensation cost			1 year 7 months 6 days
Unvested restricted stock units
Share-based awards
Fair value of RSUs vested			$ 3,100	$ 1,500	$ 5,800
Unrecognized stock compensation cost, unvested RSUs			$ 11,800
Weighted-average amortization period of unrecognized stock compensation cost			2 years 4 months 24 days
Unvested restricted stock units \| Non-employee director
Share-based awards
Vesting period			1 year
Unvested restricted stock units \| Minimum
Share-based awards
Vesting period			1 year
Unvested restricted stock units \| Maximum
Share-based awards
Vesting period			4 years
2017 Plan
Share-based awards
Cumulative annual increase in number of shares issuable, percentage		4.00%
Additional shares authorized (in shares)	4,205,794
Grants in period (in shares)			7,211,153
Number of shares available for future issuance (in shares)			2,043,328
2017 Plan \| Maximum
Share-based awards
Expiration period			10 years
2017 Plan \| Stock options
Share-based awards
Vesting period			4 years
2017 Plan \| Stock options \| Board of Directors
Share-based awards
Vesting period			3 years
2017 Plan \| Stock options \| Non-employee director
Share-based awards
Vesting period			1 year
Inducement Award Program
Share-based awards
Grants in period (in shares)			877,575
Number of shares available for future issuance (in shares)			1,170,752
Number of shares authorized (in shares)							2,000,000
Prior to Inducement Award Program
Share-based awards
Number of shares authorized (in shares)			457,500
2017 ESPP \| Employee stock purchase plan
Share-based awards
Additional shares authorized (in shares)	450,000
Number of shares available for future issuance (in shares)			364,283
Number of shares reserved for future issuance (in shares)						225,000
Purchase of common stock under ESPP (in shares)			381,508	270,774
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