v3.25.4
Schedule 3 - Supplementary Insurance Information (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]      
Earned Premiums $ 4,396.3 $ 4,215.9 $ 4,529.4
Other Income (Loss) (2.0) 10.5 10.1
Net Investment Income 405.0 407.5 419.7
Insurance Claims and Policy- holders’ Benefits 3,375.5 3,013.1 3,820.0
Amortization of Deferred Policy Acquisition Costs 574.0 538.0 607.1
Other Insurance Expenses 641.0 642.1 758.5
Deferred Policy Acquisition Costs 656.7 630.0  
Insurance Reserves 6,227.7 5,821.0  
Unearned Premiums 1,245.2 1,275.3  
Non-Core Operations      
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]      
Earned Premiums 77.2 245.6 509.3
Premiums Written 59.4 108.3 435.5
Other Income (Loss) 0.0 0.4 0.4
Net Investment Income 7.7 36.4 48.7
Insurance Claims and Policy- holders’ Benefits 59.4 236.8 434.6
Amortization of Deferred Policy Acquisition Costs 9.6 31.3 71.0
Other Insurance Expenses 56.7 51.0 75.6
Deferred Policy Acquisition Costs 0.8 4.1  
Insurance Reserves 161.9 261.7  
Unearned Premiums 32.5 50.3  
Corporate and Other      
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]      
Earned Premiums 0.0 0.0 0.0
Other Income (Loss) (12.5) 2.9 3.1
Net Investment Income (2.1) 10.9 9.3
Insurance Claims and Policy- holders’ Benefits 0.2 0.1 0.1
Amortization of Deferred Policy Acquisition Costs 0.0 0.0 0.0
Other Insurance Expenses 47.7 66.2 201.9
Deferred Policy Acquisition Costs 0.0 0.0  
Insurance Reserves 7.0 9.0  
Unearned Premiums 0.0 0.0  
Specialty Property & Casualty Insurance | Operating Segments      
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]      
Earned Premiums 3,925.7 3,576.4 3,632.5
Premiums Written 3,912.8 3,685.4 3,305.4
Other Income (Loss) 8.9 6.1 6.1
Net Investment Income 211.2 189.6 168.3
Insurance Claims and Policy- holders’ Benefits 3,077.2 2,541.7 3,141.9
Amortization of Deferred Policy Acquisition Costs 534.9 474.1 496.2
Other Insurance Expenses 301.7 285.4 245.1
Deferred Policy Acquisition Costs 158.8 162.8  
Insurance Reserves 2,769.4 2,347.9  
Unearned Premiums 1,204.2 1,216.8  
Life Insurance | Operating Segments      
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]      
Earned Premiums 393.4 393.9 387.6
Other Income (Loss) 1.6 1.1 0.5
Net Investment Income 188.2 170.6 193.4
Insurance Claims and Policy- holders’ Benefits 238.7 234.5 243.4
Amortization of Deferred Policy Acquisition Costs 29.5 32.6 39.9
Other Insurance Expenses 234.9 239.5 $ 235.9
Deferred Policy Acquisition Costs 497.1 463.1  
Insurance Reserves 3,289.4 3,202.4  
Unearned Premiums $ 8.5 $ 8.2