v3.25.4
RESERVE FOR LOSSES AND LAE - Narrative (Details)
$ in Millions
 12 Months Ended
Dec. 20, 2019
USD ($)
Dec. 31, 2025
USD ($)
group
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Dec. 31, 2015
USD ($)
Sep. 30, 2025
USD ($)
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Current year losses   $ 10,202 $ 9,967 $ 8,432      
Prior years loss development   657 1,300 (5)      
Funds held under reinsurance treaties   267 27        
Funds held by reinsureds   1,326 1,218        
Incurred losses and LAE   10,859 11,305 8,427      
Policyholder benefits and claims incurred, ceded   1,698 1,624 651      
Plus reinsurance recoverables on unpaid losses   $ 3,715 2,915 2,098 $ 2,105    
Number of exposure groupings | group   250          
Contracts of insurance and reinsurance received claims during the past three years, (in years)   20 years          
Liabilities retroceded, (in percent)           100.00%  
Retrocession agreement, consideration transferred           $ 140  
Maximum liability retroceded $ 450         440  
Total amount of liabilities retroceded           $ 300  
Reinsurance receivable $ 43            
Reinsurance recoverable for paid and unpaid losses   $ 5,100 3,100        
State National Insurance Company, Inc.              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Reinsurance recoverable for paid and unpaid losses   1,253          
Mt Logan Re              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Reinsurance recoverable for paid and unpaid losses   $ 411          
Mt Logan Re | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Percentage threshold of unrealized losses not exceeded by any one single issuer (in percent)   8.10%          
Munich Reinsurance Company              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Reinsurance recoverable for paid and unpaid losses   $ 289          
Munich Reinsurance Company | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Percentage threshold of unrealized losses not exceeded by any one single issuer (in percent)   5.70%          
Other Retrocessionaire | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Percentage threshold of unrealized losses not exceeded by any one single issuer (in percent)   5.00%          
Reinsurance Contract [Axis]: Adverse Development Cover Reinsurance Agreements              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Funds held under reinsurance treaties   $ 5,000         $ 5,400
Deferred gain on sale current   3          
Policyholder benefits and claims incurred, ceded   1,253          
Reinsurance Contract [Axis]: Adverse Development Cover Reinsurance Agreements | State National Reinsurer              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Payments for reinsurance   1,300          
Reinsurance, amount retained, per policy   $ 1,300          
Reinsurance, excess retention (in percent)   85.70%          
Reinsurance, excess retention, amount reinsured, per policy   $ 600          
Funds held by reinsureds   250          
Reinsurance, excess retention unexpired limit, amount reinsured, per policy   597          
Reinsurance Contract [Axis]: Adverse Development Cover Reinsurance Agreements | MS Transverse Reinsurance              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Payments for reinsurance   $ 122          
Reinsurance, excess retention (in percent)   80.00%          
Reinsurance, excess retention, amount reinsured, per policy   $ 400          
Incurred losses and LAE   122          
Reinsurance, excess retention unexpired limit, amount reinsured, per policy   400          
Insurance              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Incurred losses and LAE   3,050 3,622 2,471      
Other              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Prior years loss development   146          
Incurred losses and LAE   292 580 266      
Reinsurance              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Incurred losses and LAE   7,517 7,103 5,690      
Asbestos And Environmental Reserves              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Prior years loss development     54        
Higher Premiums Earned              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Current year losses   308          
Higher Premiums Earned | Reinsurance              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Prior years loss development     684        
Catastrophe Losses              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Current year losses   $ (73) 423        
Attritional Losses              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Prior years loss development       (401) $ 110    
Attritional Losses | Insurance              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Prior years loss development     1,100 $ 285      
Attritional Losses | Other              
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]              
Prior years loss development     $ 403