v3.25.4
Business Segments - Segment Assets (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Segment Reporting Information [Line Items]      
Total Assets $ 12,472.7 $ 12,630.4 $ 12,742.7
Operating Segments      
Segment Reporting Information [Line Items]      
Total Assets 11,772.3 11,084.6 11,044.0
Corporate and Other      
Segment Reporting Information [Line Items]      
Total Assets 332.3 774.7 623.7
Non-Core Operations      
Segment Reporting Information [Line Items]      
Total Assets 368.1 771.1 1,075.0
Specialty Property & Casualty Insurance | Operating Segments      
Segment Reporting Information [Line Items]      
Total Assets 6,932.8 6,352.9 6,145.9
Specialty Property & Casualty Insurance | Operating Segments | Variable Interest Entity, Primary Beneficiary      
Segment Reporting Information [Line Items]      
Total Assets 74.5 41.5 4.6
Life Insurance | Operating Segments      
Segment Reporting Information [Line Items]      
Total Assets $ 4,839.5 $ 4,731.7 $ 4,898.1