v3.26.1
Loss and Loss Adjustment Expense Reserves - Narrative (Details) - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Dec. 31, 2024
Liability for Claims and Claims Adjustment Expense [Line Items]        
Loss and loss adjustment expenses $ 207,000,000.0 $ 261,800,000    
P&C Insurance and Reinsurance (Ark/WM Outrigger)        
Liability for Claims and Claims Adjustment Expense [Line Items]        
Favorable prior loss reserve development (18,300,000) (52,800,000)    
Loss and loss adjustment expense reserves 2,585,600,000 2,253,900,000 $ 2,481,000,000 $ 2,127,500,000
Loss and loss adjustment expenses 206,700,000 233,500,000    
P&C Insurance and Reinsurance (Ark/WM Outrigger) | Operating Segments        
Liability for Claims and Claims Adjustment Expense [Line Items]        
Loss and loss adjustment expense reserves 2,585,600,000   2,481,000,000  
Loss and loss adjustment expenses 206,700,000 233,500,000    
HG Global | Operating Segments        
Liability for Claims and Claims Adjustment Expense [Line Items]        
Loss and loss adjustment expense reserves 0   $ 0  
Loss and loss adjustment expenses $ 0 $ 0