Common stock (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022	Oct. 31, 2015
Class of Stock [Line Items]
Common Stock, Shares Authorized	120,000,000	120,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Shares available for future issuance (in shares)	14,550,002	12,778,375
2015 Stock Option Plan
Class of Stock [Line Items]
Shares available for future issuance (in shares)	3,572,195	3,536,932	1,311,812
2015 Employee Stock Purchase Plan.
Class of Stock [Line Items]
Shares available for future issuance (in shares)	2,158,966	1,884,309
Employee Stock Option [Member]
Class of Stock [Line Items]
Shares available for future issuance (in shares)	7,425,444	6,199,571
Unvested restricted common stock units
Class of Stock [Line Items]
Shares available for future issuance (in shares)	1,370,897	1,112,563
Founders restricted stock
Class of Stock [Line Items]
Shares available for future issuance (in shares)	22,500	45,000