Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
Total operating revenue	$ 989,399	$ 880,701
Total operating expenses	838,023	741,889
Operating income	151,376	138,812
Total investment income	19,536	15,079
Other income	3,834	3,411
Income tax expense	36,329	32,750
Net income	$ 138,417	$ 124,552
Erie Insurance Exchange
Segment Reporting Information [Line Items]
Depreciation and amortization expense reimbursed from the Exchange and its insurance subsidiaries (as a percent)	29.00%	27.00%
Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	$ 989,399	$ 880,701
Commissions	436,860	375,760
Underwriting and policy processing	51,260	48,168
Information technology	64,785	53,490
Sales and advertising	17,375	17,207
Customer service	11,687	10,080
Administrative and other	45,783	45,617
Total operating expenses	838,023	741,889
Operating income	151,376	138,812
Total investment income	19,536	15,079
Other income	3,834	3,411
Income tax expense	36,329	32,750
Net income	138,417	124,552
Depreciation and amortization expense	15,800	13,300
Management fee revenue | Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	772,694	682,620
Administrative services reimbursement revenue
Segment Reporting Information [Line Items]
Total operating revenue	210,273	191,567
Total operating expenses	210,273	191,567
Administrative services reimbursement revenue | Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	210,273	191,567
Total operating expenses	210,273	191,567
Service agreement revenue
Segment Reporting Information [Line Items]
Total operating revenue	6,432	6,514
Service agreement revenue | Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	6,432	6,514
Management fee revenue - policy issuance and renewal services
Segment Reporting Information [Line Items]
Total operating revenue	755,049	665,686
Total operating expenses	627,750	550,322
Management fee revenue - policy issuance and renewal services | Management Operations
Segment Reporting Information [Line Items]
Total operating expenses	$ 627,750	$ 550,322