v3.26.3
Reserve for Unpaid Losses and Loss Adjustment Expenses (Tables)
 9 Months Ended
Sep. 30, 2026
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]  
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block]
Unfavorable (Favorable) Prior Accident Year Development
For the nine months ended September 30,
20262025
Workers’ compensation$(167)$(188)
Workers’ compensation discount accretion34 34 
General liability116 — 
Marine1 — 
Commercial property(25)(28)
Professional liability(9)(11)
Bond(32)(22)
Assumed reinsurance5 — 
Commercial automobile liability26 — 
Personal automobile liability(59)(55)
Homeowners(36)(36)
Catastrophes(50)(39)
Uncollectible reinsurance— 6 
Other reserve re-estimates, net (17)(9)
Prior accident year development before change in deferred gain(213)(348)
Change in deferred gain on retroactive reinsurance included in other liabilities [1](533)(64)
Total prior accident year development$(746)$(412)
[1]The change in deferred gain on retroactive reinsurance for the nine months ended September 30, 2026 includes $36 related to amortization of the A&E ADC deferred gain and $497 reflecting a net gain from the Commutation Agreement associated with the A&E ADC. The change in deferred gain on retroactive reinsurance for the nine months ended September 30, 2025 is comprised of a $64 benefit for amortization of the Navigators ADC deferred gain. For additional information regarding the ADC reinsurance agreements, refer to Note 8 - Reinsurance and "Change in Deferred Gain on Retroactive Reinsurance" discussion below.
Property, Liability and Casualty Insurance Product Line  
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]  
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block]
Rollforward of Liabilities for Unpaid Losses and Loss Adjustment Expenses
For the nine months ended September 30,
20262025
Beginning liabilities for unpaid losses and loss adjustment expenses, gross$38,155 $36,404 
Reinsurance and other recoverables6,723 6,753 
Beginning liabilities for unpaid losses and loss adjustment expenses, net31,432 29,651 
Provision for unpaid losses and loss adjustment expenses
Current accident year8,717 8,401 
Prior accident year development [1](746)(412)
Total provision for unpaid losses and loss adjustment expenses7,971 7,989 
Effect of the Commutation Agreement [2]1,298 — 
Change in deferred gain on retroactive reinsurance included in other liabilities [1]533 64 
Payments
Current accident year(1,973)(2,038)
Prior accident years(4,993)(4,586)
Total payments(6,966)(6,624)
Foreign currency adjustment(6)32 
Ending liabilities for unpaid losses and loss adjustment expenses, net34,262 31,112 
Reinsurance and other recoverables5,187 6,627 
Ending liabilities for unpaid losses and loss adjustment expenses, gross$39,449 $37,739 
[1]Prior accident year development for the nine months ended September 30, 2026 included a $533 benefit related to a change in deferred gain under retroactive reinsurance accounting for the A&E ADC, including $36 related to amortization of the deferred gain and a $497 benefit reflecting the impact of the Commutation Agreement in the third quarter of 2026. Prior accident year development for the nine months ended September 30, 2025 included a $64 benefit for amortization of a deferred gain under retroactive reinsurance accounting related to the Navigators Adverse Development Cover (the "Navigators' ADC"). The Navigators' ADC deferred gain has been fully amortized as of September 30, 2025. For additional information regarding the adverse development cover ("ADC") reinsurance agreements, refer to Note 8 - Reinsurance and "Change in Deferred Gain on Retroactive Reinsurance" discussion below.
[2]Represents net unpaid losses and loss adjustment expenses reserves reassumed, resulting from the Commutation Agreement associated with the A&E ADC. For additional information regarding the Commutation Agreement, refer to Note 8 - Reinsurance.
Group Insurance Policy [Member]  
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]  
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block]
Rollforward of Liabilities for Unpaid Losses and Loss Adjustment Expenses
For the nine months ended September 30,
20262025
Beginning liabilities for unpaid losses and loss adjustment expenses, gross$8,113 $8,206 
Reinsurance recoverables282 282 
Beginning liabilities for unpaid losses and loss adjustment expenses, net7,831 7,924 
Provision for unpaid losses and loss adjustment expenses
Current incurral year4,096 3,949 
Prior year's discount accretion162 153 
Prior incurral year development [1](339)(486)
Total provision for unpaid losses and loss adjustment expenses [2]3,919 3,616 
Payments
Current incurral year(1,996)(1,899)
Prior incurral years(1,795)(1,841)
Total payments(3,791)(3,740)
Ending liabilities for unpaid losses and loss adjustment expenses, net7,959 7,800 
Reinsurance recoverables306 281 
Ending liabilities for unpaid losses and loss adjustment expenses, gross$8,265 $8,081 
[1]Prior incurral year development represents the change in estimated ultimate incurred losses and loss adjustment expenses for prior incurral years on a discounted basis.
[2]Includes unallocated loss adjustment expenses ("ULAE") of $138 and $129 for the nine months ended September 30, 2026 and 2025, respectively, that are recorded in insurance operating costs and other expenses in the Condensed Consolidated Statements of Operations