v3.25.2
Investments - Distribution of Fixed Maturity Securities by Expected Maturity (Details) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Amortized Cost, net    
Due in 1 year or less $ 2,251.8  
Due after 1 year through 5 years 925.6  
Due after 5 years through 10 years 925.0  
Due after 10 years through 20 years 981.5  
Due after 20 years 763.5  
Amortized Cost, net 5,847.4 $ 5,842.5
Fair Value    
Due in 1 year or less 2,189.5  
Due after 1 year through 5 years 898.5  
Due after 5 years through 10 years 893.4  
Due after 10 years through 20 years 859.8  
Due after 20 years 612.1  
Total $ 5,453.3 $ 5,387.9
Percent of Total Fair Value    
Due in 1 year Or less (percent) 40.20%  
Due after 1 year through 5 years (percent) 16.50%  
Due after 5 years through 10 years (percent) 16.40%  
Due after 10 years through 20 years (percent) 15.80%  
Due after 20 years (percent) 11.20%  
Total (percent) 100.00%  
Average option-adjusted duration, in years 5 years 8 months 12 days