Postretirement Benefits - Employee Savings Plan (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Employee savings plan
Employer matching contribution paid to the plan	$ 21.0	$ 18.4	$ 16.7
Class A common stock held by plan participants (in shares)	0.1	0.1
Erie Insurance Exchange (EIE)
Employee savings plan
Matching contributions reimbursed to Indemnity from the Exchange and its subsidiaries (as a percent)	61.00%
100% employer matching contribution
Employee savings plan
Percentage of employer matching contribution of employee contributions	100.00%
100% employer matching contribution | Maximum
Employee savings plan
Percentage of eligible employee compensation, matched by employer	3.00%
50% employer matching contribution
Employee savings plan
Percentage of employer matching contribution of employee contributions	50.00%
50% employer matching contribution | Maximum
Employee savings plan
Percentage of eligible employee compensation, matched by employer	5.00%
50% employer matching contribution | Minimum
Employee savings plan
Percentage of eligible employee compensation, matched by employer	3.00%