v3.26.1
Reserve for Losses and Loss Adjustment Expenses - Reserve for Losses and Loss Adjustment Expenses, Net of Reinsurance (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease) [Abstract]      
Reserve for losses and loss adjustment expenses net of reinsurance recoverables at beginning of period $ 1,071,699 $ 1,086,278 $ 1,086,278
Add: Incurred losses and loss adjustment expenses net of reinsurance:      
Current year 94,136 101,584  
Prior years - retroactive reinsurance 14,189 (1,928)  
Prior years - excluding retroactive reinsurance (165) (131)  
Total incurred losses and loss and adjustment expenses 108,160 99,525  
Deduct: Loss and loss adjustment expense payments net of reinsurance:      
Current year 900 1,731  
Prior years 93,151 90,239  
Total loss and loss adjustment expense payments 94,051 91,970  
Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period 1,071,619 1,095,761 1,071,699
Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period 2,016,229 1,985,779  
Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period 3,087,848 3,081,540 $ 3,099,418
Excess & Surplus Lines      
Add: Incurred losses and loss adjustment expenses net of reinsurance:      
Prior years - retroactive reinsurance 14,189 (1,928)  
Prior years - excluding retroactive reinsurance (100) (10)  
Deduct: Loss and loss adjustment expense payments net of reinsurance:      
Deduct: Change in deferred reinsurance gain - retroactive reinsurance $ 14,189 $ (1,928)