v3.26.1
Investments Equity Securities (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Equity securities $ 2,679.0 $ 2,487.7
Equity Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Equity securities, gross unrealized gains 1,380.6 1,134.4
Equity securities, gross unrealized losses 19.8 24.3
Equity securities - cost 1,318.2 1,377.7
Equity securities $ 2,679.0 $ 2,487.7