Postretirement Benefits - Pension Plan (Income) Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cost of pension plans:
Service cost for benefits earned	$ 34,554	$ 28,763	$ 50,242
Interest cost on benefit obligation	52,688	50,193	39,764
Expected return on plan assets	(80,793)	(68,869)	(54,557)
Prior service cost amortization	1,611	1,446	1,443
Net actuarial (gain) loss amortization	(6,859)	(15,331)	7,320
Settlements	(1,338)	0	0
Pension plan (income) cost	$ (137)	$ (3,798)	$ 44,212
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)	60.00%
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)	34.00%