v3.26.3
Postretirement Benefits - Narrative (Details) - USD ($)
$ in Millions
1 Months Ended 9 Months Ended
Aug. 31, 2026
Jan. 31, 2026
Sep. 30, 2026
Employee pension plan      
Postretirement Benefits      
Funding target (as a percentage of the funding target liability)     100.00%
Defined benefit plan, plan assets, contributions by employer $ 30 $ 47  
Erie Insurance Exchange | Employee pension plan      
Postretirement Benefits      
Postretirement annual benefit expense reimbursed from the Exchange and its insurance subsidiaries (as a percent)     61.00%
Erie Insurance Exchange | Supplemental employee retirement plan (SERP)      
Postretirement Benefits      
Postretirement annual benefit expense reimbursed from the Exchange and its insurance subsidiaries (as a percent)     33.00%