v3.26.1
Reserve for Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Nov. 11, 2024
Jul. 02, 2024
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2024
Reserve For Losses And Loss Adjustment Expenses [Line Items]                    
Allowance for credit losses on reinsurance recoverables     $ 1,700 $ 1,500 $ 1,700 $ 1,500 $ 1,600 $ 1,700 $ 1,500 $ 1,200
Development on prior year loss adverse (favorable) reserves     569 3,027 404 2,896        
Reduction in pre-tax income     (8,461) (7,327) 2,174 (23,336)        
Adverse prior year development ceded on subject business     6,927 9,239 21,116 7,311        
Excess & Surplus Lines                    
Reserve For Losses And Loss Adjustment Expenses [Line Items]                    
Development on prior year loss adverse (favorable) reserves     275 2,300 175 2,300        
Adverse prior year development ceded on subject business     6,927 9,239 21,116 7,311        
Excess & Surplus Lines | Commercial Auto LPT | Commercial Auto LPT                    
Reserve For Losses And Loss Adjustment Expenses [Line Items]                    
Cumulative amounts ceded under loss portfolio transfer     451,400   451,400   451,400      
Adverse prior year development ceded on subject business     (40) (1,414) (40) (1,270)        
Excess & Surplus Lines | E&S ADC                    
Reserve For Losses And Loss Adjustment Expenses [Line Items]                    
Development on prior year loss adverse (favorable) reserves             35,000      
Reinsure excess amount   $ 716,600                
Reinsurance, aggregate coverage limit $ 1,183,700 467,100                
Payments for reinsurance   $ 313,200                
Adverse prior year development ceded on subject business     0 10,582 0 10,582        
Excess & Surplus Lines | E&S ADC | State National                    
Reserve For Losses And Loss Adjustment Expenses [Line Items]                    
Reinsure percentage   85.00%                
Reinsurance, aggregate coverage limit   $ 397,000                
Excess & Surplus Lines | E&S Top Up ADC                    
Reserve For Losses And Loss Adjustment Expenses [Line Items]                    
Development on prior year loss adverse (favorable) reserves         23,600   51,400      
Reinsure percentage 100.00%                  
Reinsurance, aggregate coverage limit $ 75,000                  
Payments for reinsurance 52,800                  
Reduction in pre-tax income $ 52,800                  
Reinsurance, amount remaining             $ 23,600      
Adverse prior year development ceded on subject business     7,455 0 22,235 0        
Specialty Admitted Insurance                    
Reserve For Losses And Loss Adjustment Expenses [Line Items]                    
Development on prior year loss adverse (favorable) reserves     $ 294 $ 700 $ 229 $ 579