v3.25.1
Investments - Schedule of Company's Gross Realized Investment Other Gains (Losses) (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Schedule of Investments [Line Items]    
Realized gains on fixed maturities and other: $ 3.8 $ 9.4
Realized losses on fixed maturities and other: (4.4) (3.1)
Other (2.5) 0.0
Total other net losses recognized on fixed maturities and other (3.0) (0.5)
Net realized gains (losses) on equity securities 0.0 0.4
Change in unrealized gains (losses) on equity securities held at the end of the period 13.3 0.0
Net gains (losses) on equity securities 13.3 0.4
Net investment and other gains (losses) before income taxes 9.7 6.2
Income tax (benefit) provision 2.8 1.6
Net investment and other gains (losses), net of income taxes 6.9 4.6
Fixed maturities    
Schedule of Investments [Line Items]    
Realized gains on fixed maturities and other: 2.2 6.8
Realized losses on fixed maturities and other: (0.3) (0.3)
Other investments, including short-term investments    
Schedule of Investments [Line Items]    
Realized gains on fixed maturities and other: 1.6 2.6
Realized losses on fixed maturities and other: (4.1) (2.8)
Credit losses on fixed maturities    
Schedule of Investments [Line Items]    
Credit losses on fixed maturities (0.3) (0.5)
Impairment related to change in intent    
Schedule of Investments [Line Items]    
Impairment related to change in intent $ (0.2) $ 0.0