v3.26.1
Segment Information (Identifiable Assets by Business Segment) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Segment Reporting Information [Line Items]    
Identifiable assets $ 16,527.7 $ 16,945.9
Identifiable assets 83.3 83.6
Property and Casualty [Member]    
Segment Reporting Information [Line Items]    
Identifiable assets 16,444.4 16,862.3
Assets of Discontinued Operations [Member]    
Segment Reporting Information [Line Items]    
Identifiable assets $ 83.3 $ 83.6