v3.24.3
Reserve for Losses and Loss Adjustment Expenses (Details) - USD ($)
$ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2024
Sep. 30, 2023
Dec. 31, 2023
Liability for Claims and Claims Adjustment Expense [Line Items]      
Minimum period for claims resolution 5 years    
Summary of reserve for losses and loss adjustment expenses      
Balance, beginning of year $ 3,401,281 $ 3,471,147 $ 3,471,147
Less reinsurance recoverables on unpaid losses and loss adjustment expenses 445,573 431,889 431,889
Net balance, beginning of year 2,955,708 3,039,258 3,039,258
Net losses:      
Current year (585,734) (596,872) (794,848)
(Favorable) unfavorable development of reserves established in prior years, net (28,709) 8,373 5,646
Total 557,025 605,245 800,494
Paid related to:      
Current year (69,750) (67,894) (101,996)
Prior years (564,602) (598,281) (782,048)
Total paid (634,352) (666,175) (884,044)
Net balance, end of period 2,878,381 2,978,328 2,955,708
Plus reinsurance recoverables on unpaid losses and loss adjustment expenses 461,302 417,323 445,573
Balance, end of period 3,339,683 3,395,651 3,401,281
Net unfavorable development medical professional liability business 600    
Net unfavorable development in workers' compensation business 1,400    
Specialty P&C      
Net losses:      
Current year 27,200    
(Favorable) unfavorable development of reserves established in prior years, net (20,900)    
Paid related to:      
Prior years (2,500)    
Net favorable prior year reserve development 1,500    
Portfolio Cell Reinsurance      
Paid related to:      
Net favorable development in workers' compensation business 2,900    
NORCAL Group      
Net losses:      
(Favorable) unfavorable development of reserves established in prior years, net $ 4,300 $ 6,700 $ 8,300