v3.23.2
Cash, Cash Equivalents, and Short-term Investments - Components (Details) - USD ($)
$ in Millions
Jun. 30, 2023
Dec. 31, 2022
Jun. 30, 2022
Current assets:      
Cash $ 105.0 $ 235.6  
Cash equivalents      
Amortized Cost 404.7 182.5  
Unrealized Losses 0.0 (0.1)  
Estimated Fair Value 404.7 182.4  
Amortized Cost 509.7 418.1  
Total cash and cash equivalents 509.7 418.0 $ 352.7
Short-term investments:      
Amortized Cost 150.8 127.8  
Unrealized Gains 0.0 0.0  
Unrealized Losses (0.2) (0.1)  
Estimated Fair Value 150.6 127.7  
Cash, cash equivalents, and short-term investments, amortized cost 660.5 545.9  
Cash, cash equivalents, and short-term investments, unrealized losses (0.2) (0.2)  
Total cash, cash equivalents, and short-term investments 660.3 545.7  
Corporate debt securities      
Cash equivalents      
Amortized Cost 231.2 159.9  
Unrealized Losses 0.0 (0.1)  
Estimated Fair Value 231.2 159.8  
Short-term investments:      
Amortized Cost 100.0 91.8  
Unrealized Losses (0.1) (0.1)  
Estimated Fair Value 99.9 91.7  
Money market mutual funds      
Cash equivalents      
Amortized Cost 173.5 18.6  
Unrealized Losses 0.0 0.0  
Estimated Fair Value 173.5 18.6  
Securities guaranteed by U.S. government      
Cash equivalents      
Amortized Cost   4.0  
Unrealized Losses   0.0  
Estimated Fair Value   4.0  
Short-term investments:      
Amortized Cost 28.6 25.0  
Unrealized Gains 0.0 0.0  
Unrealized Losses (0.1) 0.0  
Estimated Fair Value 28.5 25.0  
Other governmental securities      
Short-term investments:      
Amortized Cost 22.2 11.0  
Unrealized Gains 0.0 0.0  
Unrealized Losses 0.0 0.0  
Estimated Fair Value $ 22.2 $ 11.0