v3.26.1
Related Party Transactions - Narrative (Details)
$ in Millions
3 Months Ended 6 Months Ended
Dec. 20, 2022
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Jan. 03, 2023
Related Party Transaction [Line Items]              
Reinsurance, profit commission, percentage       0.200      
Reinsurance, profit commission, hurdle rate of return, percentage       0.050      
Related Party              
Related Party Transaction [Line Items]              
Other receivables   $ 239.6   $ 239.6   $ 174.8  
Amounts due to The Fidelis Partnership   640.1   $ 640.1   $ 457.7  
Framework Agreement | Related Party              
Related Party Transaction [Line Items]              
Related party transaction, agreement duration 10 years            
Reinsurance, ceded commission, percentage       0.115      
Property management fee, percent fee       3.00%      
Reinsurance premiums, percentage       1.00%      
Insurance commissions   27.3 $ 25.3 $ 53.8 $ 55.2    
Payments for commissions   23.3   35.3      
Recovery of commissions     (25.5)   (16.2)    
Framework Agreement | Related Party | Income Statement Location [Axis]: us-gaap:GeneralAndAdministrativeExpense              
Related Party Transaction [Line Items]              
Costs and expenses, related party   1.0 0.7 2.3 1.8    
Framework Agreement | Related Party | Income Statement Location [Axis]: fihl:PolicyAcquisitionExpense              
Related Party Transaction [Line Items]              
Insurance commissions   $ 4.7 $ 21.6 $ 6.8 $ 33.3    
Framework Agreement | Related Party | Third Party Managing General Underwriters              
Related Party Transaction [Line Items]              
Reinsurance, ceded commission, percentage       0.030      
Group | Framework Agreement | Related Party | Fidelis MGU              
Related Party Transaction [Line Items]              
Subsidiary, ownership percentage, noncontrolling owner             9.90%