v3.26.1
Business Segments - Earned Premiums by Product Line (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]        
Earned Premiums [1] $ 1,011.6 $ 1,130.8 $ 2,010.9 $ 2,218.7
Life Insurance        
Segment Reporting [Line Items]        
Earned Premiums (0.2) (0.9) 0.7 (0.7)
Operating Segments        
Segment Reporting [Line Items]        
Earned Premiums 999.3 1,111.3 1,985.3 2,173.2
Operating Segments | Specialty Property & Casualty Insurance        
Segment Reporting [Line Items]        
Earned Premiums 896.6 1,010.8 1,781.8 1,973.0
Operating Segments | Life Insurance        
Segment Reporting [Line Items]        
Earned Premiums 102.7 100.5 203.5 200.2
Operating Segments | Personal Automobile | Specialty Property & Casualty Insurance        
Segment Reporting [Line Items]        
Earned Premiums 647.4 789.3 1,294.4 1,543.0
Operating Segments | Commercial Automobile | Specialty Property & Casualty Insurance        
Segment Reporting [Line Items]        
Earned Premiums 249.2 221.5 487.4 430.0
Operating Segments | Life | Life Insurance        
Segment Reporting [Line Items]        
Earned Premiums 87.5 84.8 173.1 168.5
Operating Segments | Accident and Health | Life Insurance        
Segment Reporting [Line Items]        
Earned Premiums 5.4 5.4 10.7 10.9
Operating Segments | Property | Life Insurance        
Segment Reporting [Line Items]        
Earned Premiums 9.8 10.3 19.7 20.8
Non-Core Operations        
Segment Reporting [Line Items]        
Earned Premiums $ 12.3 $ 19.5 $ 25.6 $ 45.5
[1]
1 Includes a remeasurement loss of $0.2 million and $0.9 million related to the deferred profit liability within the Life Insurance business for the three months ended June 30, 2026 and 2025, respectively, and a remeasurement gain of $0.7 million for the six months ended June 30, 2026 and a remeasurement loss of $0.7 million for the six months ended June 30, 2025.