v3.26.1
Investments - Available-for-Sale Debt Securities (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 1,930.0 $ 3,036.1
Gross Unrealized Gains 1.0 14.2
Gross Unrealized Losses (9.5) (0.3)
Fair Value 1,921.5 3,050.0
U.S. government and agency securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 1,575.2 2,433.0
Gross Unrealized Gains 0.7 10.5
Gross Unrealized Losses (8.2) (0.3)
Fair Value 1,567.7 2,443.2
Corporate debt securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 354.8 603.1
Gross Unrealized Gains 0.3 3.7
Gross Unrealized Losses (1.3) 0.0
Fair Value $ 353.8 $ 606.8