Income Taxes - Schedule of Tax Credits and Operating Loss Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss	$ 20.4	$ 28.7
Federal | R&D credits
Operating Loss Carryforwards [Line Items]
Tax credits	0.0	0.0
Federal | Foreign tax credits
Operating Loss Carryforwards [Line Items]
Tax credits	0.1	0.0
State | California
Operating Loss Carryforwards [Line Items]
Net operating loss	167.7	185.0
State | California | R&D credits
Operating Loss Carryforwards [Line Items]
Tax credits	111.9	96.4
State | California | AMT Tax Credits
Operating Loss Carryforwards [Line Items]
Tax credits	0.5	0.0
State | Other states
Operating Loss Carryforwards [Line Items]
Net operating loss	7.8	8.5
Foreign | UK
Operating Loss Carryforwards [Line Items]
Net operating loss	0.0	90.5
Foreign | Other foreign
Operating Loss Carryforwards [Line Items]
Net operating loss	$ 6.0	$ 9.7