XML 218 R171.htm IDEA: XBRL DOCUMENT v3.25.4
Benefit Plans - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Components of net periodic cost    
Percentage related to domestic plan 89.00%  
Percentage related to domestic plan and former final average pay formula 73.00%  
Maximum annual medical cost inflation after retirement for Company's share of retiree medical benefits cost for non Medicare-eligible retirees (as a percent) 5.00%  
Components of net periodic cost    
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration] Allstate Protection and Run-off Property-Liability net investment income, Operating costs and expenses, Claims and claims expense, Restructuring and related charges  
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Allstate Protection and Run-off Property-Liability net investment income, Operating costs and expenses, Claims and claims expense, Restructuring and related charges  
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Allstate Protection and Run-off Property-Liability net investment income, Operating costs and expenses, Claims and claims expense, Restructuring and related charges  
Pension benefits    
Components of net periodic cost    
Accumulated benefit obligation $ 4,360 $ 4,360
Defined benefit plans' accrued benefit costs related to certain unfunded and non-qualified plans $ 72 $ 74
Postretirement benefits    
Defined benefit plan, assumed health care cost trend rates    
Weighted average health care cost trend rate (as a percent) 8.00%  
Ultimate health care cost trend rate in 2035 and thereafter (as a percent) 4.50%