v3.26.1
Insurance Contracts - Summary of Loss Reserve Roll-Forward, Net of Subrogation Recoverable and Reinsurance (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Dec. 31, 2024
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Beginning balance of net loss and loss expense reserves     $ 84,268 $ 78,981    
Current Year Claims and Claims Adjustment Expense $ 23,949 $ 21,144        
Prior Year Claims and Claims Adjustment Expense 9,076 330        
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims 33,025 21,474        
Claim and loss expense payments, net of subrogation and reinsurance (2,249) (2,745)        
Claim and loss expense (payments) recoveries, net of subrogation and reinsurance (23,460) (19,155)        
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid 25,709 21,900        
Liability for Unpaid Claims and Claims Adjustment Expense, Net 91,584 78,555 91,584 78,555 $ 84,268 $ 78,981
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 407,459 305,414 407,459 305,414 375,722 270,081
Policyholder Benefits and Claims Incurred, Ceded     95,878 89,957    
Ceded Loss And Loss Expenses Paid Not Yet Recovered 88,194 71,031 88,194 71,031    
Liability for Claims and Claims Adjustment Expense 499,043   499,043   459,990  
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 91,584   91,584      
Liability for Claim and Claim Adjustment Expenses Net of Subrogation recoverables 499,043 $ 383,969 499,043 $ 383,969 $ 459,990 $ 349,062
Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 407,459   407,459      
Insurance Claims            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Prior Year Claims and Claims Adjustment Expense     2,125      
Loss Adjustment Expenses (Legal Expenses)            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Prior Year Claims and Claims Adjustment Expense     5,787      
Segment Reporting, Reconciling Item, Corporate Nonsegment | Other Insurance Contracts            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Liability for Claims and Claims Adjustment Expense 21,229   21,229      
Operating Segments | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Liability for Claims and Claims Adjustment Expense 499,043   499,043      
Operating Segments | Commercial Auto            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 120,850   120,850      
Liability for Claims and Claims Adjustment Expense 139,879   139,879      
Operating Segments | Commercial Auto | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 19,029   19,029      
Operating Segments | Excess and General Liability            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 126,873   126,873      
Liability for Claims and Claims Adjustment Expense 148,594   148,594      
Operating Segments | Excess and General Liability | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 21,721   21,721      
Operating Segments | General Liability            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 51,522   51,522      
Liability for Claims and Claims Adjustment Expense 65,246   65,246      
Operating Segments | General Liability | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 13,724   13,724      
Operating Segments | Workers' Compensation Insurance            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 0   0      
Liability for Claims and Claims Adjustment Expense 20,500   20,500      
Operating Segments | Workers' Compensation Insurance | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 20,500   20,500      
Operating Segments | Non-standard Personal Auto            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 189   189      
Liability for Claims and Claims Adjustment Expense 2,275   2,275      
Operating Segments | Non-standard Personal Auto | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 2,086   2,086      
Operating Segments | Professional Liability Insurance            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 48,564   48,564      
Liability for Claims and Claims Adjustment Expense 52,184   52,184      
Operating Segments | Professional Liability Insurance | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 3,620   3,620      
Operating Segments | Multi-peril            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 13,986   13,986      
Liability for Claims and Claims Adjustment Expense 17,898   17,898      
Operating Segments | Multi-peril | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 3,912   3,912      
Operating Segments | Surety Product Line            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 11,189   11,189      
Liability for Claims and Claims Adjustment Expense 12,985   12,985      
Operating Segments | Surety Product Line | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 1,796   1,796      
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment | Other Insurance Contracts            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 23,093   23,093      
Liability for Claims and Claims Adjustment Expense 23,317   23,317      
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment | Other Insurance Contracts | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net 225   225      
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment | Unallocated Loss Adjustment Expense Reserve            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments 11,194   11,194      
Liability for Claims and Claims Adjustment Expense 16,165   16,165      
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment | Unallocated Loss Adjustment Expense Reserve | Specialty Property & Casualty Program            
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]            
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net $ 4,971   $ 4,971