Income taxes - Losses before income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income taxes
United States	$ (7,222)	$ (11,403)	$ (11,603)
Foreign (Austria)	(57,463)	(64,261)	(32,479)
Net loss before tax	$ (64,685)	$ (75,664)	$ (44,082)
Company's worldwide effective tax rate	0.30%	0.00%	0.00%

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details