v3.25.1
Loss and Loss Adjustment Expense Reserves - LAE Reserve Activity (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Loss and LAE incurred relating to:    
Net incurred loss and LAE $ 261.8 $ 185.8
P&C Insurance and Reinsurance (Ark/WM Outrigger)    
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]    
Gross beginning balance 2,127.5 1,605.1
Less: beginning reinsurance recoverable on unpaid losses (434.4) (340.8)
Net loss and LAE reserves 1,693.1 1,264.3
Loss and LAE incurred relating to:    
Current year losses 286.3 180.3
Prior year losses (52.8) (0.3)
Net incurred loss and LAE 233.5 180.0
Loss and LAE paid relating to:    
Current year losses (83.2) (4.0)
Prior year losses (75.8) (96.7)
Net paid loss and LAE (159.0) (100.7)
Foreign currency translation and other adjustments to loss and LAE reserves 5.7 (3.6)
Net ending balance 1,773.3 1,340.0
Plus: ending reinsurance recoverable on unpaid losses (480.6) (404.5)
Gross ending balance $ 2,253.9 $ 1,744.5