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	$ 37.8
Deferred tax liabilities, foreign withholding tax	4.7	$ 0.0
Valuation allowance increase	$ 37.8
Effective income tax rate reconciliation, percent	3.00%	28.00%	26.00%
Unrecognized tax benefits, noncurrent	$ 6.8	$ 12.7
Gross unrecognized tax benefits	6.8	12.7	$ 12.2	$ 8.9
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations	5.1	0.0	0.0
Unrecognized tax benefits, income tax penalties and interest accrued	1.6	3.7
Unrecognized tax benefits, income tax penalties and interest expense	(2.1)	$ 1.1	$ 0.4
Domestic Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards	70.5
Operating loss carryforwards, subject to expiration	36.0
Operating loss carryforwards, not subject to expiration	34.5
Tax credit carryforward, amount	13.4
State and Local Jurisdiction | Maryland
Income Tax Contingency [Line Items]
Operating loss carryforwards	1,700.0
State and Local Jurisdiction | California
Income Tax Contingency [Line Items]
Operating loss carryforwards	146.5
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