v3.25.4
Property and Casualty Insurance Reserves - Reserve Activity (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]      
Gross of Reinsurance at Beginning of Year $ 5,811.6    
Less: Reinsurance Recoverables at Beginning of Year 78.7    
Paid Losses and LAE related to:      
Plus: Reinsurance Recoverables at End of Year 78.1 $ 78.7  
Property and Casualty Insurance Reserves, Gross of Reinsurance at End of Year 6,198.3 5,811.6  
Property and Liability Insurance      
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]      
Gross of Reinsurance at Beginning of Year 2,611.9 2,680.5 $ 2,756.9
Less: Reinsurance Recoverables at Beginning of Year 24.3 27.8 39.6
Property and Casualty Insurance Reserves, Net of Reinsurance at Beginning of Year 2,587.6 2,652.7 2,717.3
Incurred Losses and LAE related to:      
Current Year 3,025.6 2,745.9 3,429.9
Prior Years 76.0 29.8 159.8
Total Incurred Losses and LAE 3,101.6 2,775.7 3,589.7
Paid Losses and LAE related to:      
Paid Losses and LAE Related to Current Year 1,424.9 1,383.0 1,965.3
Paid Losses and LAE Related to Prior Years 1,379.1 1,457.8 1,689.0
Total Paid Losses and LAE 2,804.0 2,840.8 3,654.3
Property and Casualty Insurance Reserves, Net of Reinsurance at End of Year 2,885.2 2,587.6 2,652.7
Plus: Reinsurance Recoverables at End of Year 25.6 24.3 27.8
Property and Casualty Insurance Reserves, Gross of Reinsurance at End of Year $ 2,910.8 $ 2,611.9 $ 2,680.5