Income taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes [Line Items]
Swiss federal statutory rate	8.50%	8.50%	8.50%
Corporate tax rate	12.00%
Non-U.S NOLs	$ 37,105
NOLs carry forwards indefinitely	4,942
Uncertain tax positions, interest and penalties recognized	2	$ 5	$ 21
Swiss Federal Tax Administration (FTA)
Income Taxes [Line Items]
Federal NOLs	525,131
State and Local Jurisdiction \| Swiss Federal Tax Administration (FTA)
Income Taxes [Line Items]
Federal NOLs	$ 497,371

Effective Income Tax Rate Reconciliation, Corporate Tax Rate, Percent

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Income taxes line items.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are not subject to expiration dates.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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