Income taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Deferred tax assets, valuation allowance	$ 69,608	$ 47,420
Valuation allowance, period increase (decrease)	22,200	28,100
Capitalized research and development expenditures	15,875	0
Unrecognized tax benefits	18,812	18,534	$ 971	$ 651
Unrecognized tax benefits that would impact effective tax rate	100
Domestic Tax Authority | Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	246,200	224,400
Domestic Tax Authority | Federal | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credit	4,700	4,000
Domestic Tax Authority | Federal | Operating Loss Carryforwards Expiration Year, Unlimited
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	237,700	215,900
State and Local Jurisdiction | California Franchise Tax Board
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	124,900	146,800
State and Local Jurisdiction | California Franchise Tax Board | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credit	$ 2,900	$ 2,300