Income taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Valuation allowance increase, including CTA component	$ 43.8
Deferred tax liabilities, foreign withholding tax	4.7	$ 0.0
Valuation allowance increase	$ 43.0
Effective income tax rate reconciliation, percent	(1.00%)	27.00%	25.00%
Unrecognized tax benefits, noncurrent	$ 1.2	$ 9.8
Gross unrecognized tax benefits	1.2	9.8	$ 9.2	$ 10.4
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations	8.0	$ 0.0	$ 0.0
Domestic Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards	73.0
Operating loss carryforwards, subject to expiration	36.0
Operating loss carryforwards, not subject to expiration	37.0
Tax credit carryforward, amount	13.4
State and Local Jurisdiction | Maryland
Income Tax Contingency [Line Items]
Operating loss carryforwards	1,900.0
State and Local Jurisdiction | California
Income Tax Contingency [Line Items]
Operating loss carryforwards	146.8
State and Local Jurisdiction | Research Tax Credit Carryforward
Income Tax Contingency [Line Items]
Tax credit carryforward, amount	5.0
Foreign Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards	51.5
Operating loss carryforwards, subject to expiration	14.5
Operating loss carryforwards, not subject to expiration	37.0
PaxVax
Income Tax Contingency [Line Items]
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations	$ 8.0