Income taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Increase (decrease) in deferred tax asset valuation allowance	$ 160.4	$ 120.7
Unrecognized tax benefits that would affect effective tax rate	250.9
Effective tax rate impact	5.3
Remaining unrecognized tax benefits	245.6
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	2,914.6
Federal | Research Tax Credits
Income Taxes [Line Items]
Tax credit carryforwards	491.4
State | California
Income Taxes [Line Items]
Net operating loss carryforwards	555.0
State | California | Research Tax Credits
Income Taxes [Line Items]
Tax credit carryforwards	365.7
State | Other States
Income Taxes [Line Items]
Net operating loss carryforwards	1,387.5
Foreign | Ireland
Income Taxes [Line Items]
Net operating loss carryforwards	208.5
Foreign | Other Foreign
Income Taxes [Line Items]
Net operating loss carryforwards	$ 10.2