Postretirement Benefits - Pension Plan Cost (Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cost of pension plans:
Service cost for benefits earned	$ 35,471	$ 34,554	$ 28,763
Interest cost on benefit obligation	58,748	52,688	50,193
Expected return on plan assets	(80,276)	(80,793)	(68,869)
Prior service cost amortization	1,688	1,611	1,446
Net actuarial gain amortization	(2,519)	(6,859)	(15,331)
Settlement gain	(572)	(1,338)	0
Pension plan cost (income)	$ 12,540	$ (137)	$ (3,798)
Defined benefit plan, net periodic benefit cost (credit) excluding service cost, statement of income or comprehensive income	Other income
Erie Insurance Exchange (EIE) | Employee Pension Plan
Postretirement benefits
Postretirement annual benefit income and expense reimbursed to and from, respectively, the Exchange and its subsidiaries (as a percent)	61.00%
Erie Insurance Exchange (EIE) | Supplemental Employee Retirement Plan (SERP)
Postretirement benefits
Postretirement annual benefit income and expense reimbursed to and from, respectively, the Exchange and its subsidiaries (as a percent)	33.00%