Marketable Securities and Fair Value Measurements (Details) - Level 2 - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 684.7	$ 937.9
Gross Unrealized Gains	1.6	1.7
Gross Unrealized Losses	(0.2)	(0.7)
Fair Value	686.1	938.9
Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	621.1	934.4
Gross Unrealized Gains	1.5	1.7
Gross Unrealized Losses	(0.2)	(0.7)
Fair Value	622.4	935.4
Government securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	63.6	3.5
Gross Unrealized Gains	0.1	0.0
Gross Unrealized Losses	0.0	0.0
Fair Value	$ 63.7	$ 3.5