v3.26.1
Concentration of Credit Risk - Additional Information (Details)
$ in Millions
12 Months Ended
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Concentration Risk [Line Items]      
Amount recoverable from reinsurers $ 4,281.9 $ 4,172.0  
Concentration risk 0.619 0.559  
Reinsurance Recoverable, Allowance for Credit Loss $ 16.2 $ 27.5 $ 3.7
Premiums Receivable, Net [1] 1,700.8 1,617.0  
Due for settlement 257.7    
Premium Receivable, Allowance for Credit Loss $ 22.9 $ 24.6  
Allowable holdings of a single issue or issuer, percentage 2.00%    
Maximum      
Concentration Risk [Line Items]      
Gross written premiums, percentage 17.20% 15.40%  
Minimum      
Concentration Risk [Line Items]      
Gross written premiums, percentage 7.60% 8.80%  
Median      
Concentration Risk [Line Items]      
Gross written premiums, percentage 15.10% 11.50%  
A- rating or higher      
Concentration Risk [Line Items]      
Concentration risk 0.373 0.440  
A- rating or lower      
Concentration Risk [Line Items]      
Concentration risk 0.008 0.001  
[1] Included within underwriting premiums receivables, reserve for losses and loss adjustment expenses and unearned premiums are related party balances of $1.6 million, $3.7 million and $1.2 million, respectively. Refer to Note 20, “Related Party Transactions” for further details.