Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Total operating revenue	$ 1,060,097		$ 990,438		$ 2,049,496	$ 1,871,139
Total operating expenses	860,924		800,230		1,698,947	1,542,119
Operating income	199,173		190,208		350,549	329,020
Total investment income	19,600		13,827		39,136	28,906
Other income	1,974		3,292		5,808	6,703
Income tax expense	46,062		43,424		82,391	76,174
Net income	174,685	$ 138,417	163,903	$ 124,552	$ 313,102	$ 288,455
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%	28.00%
Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	1,060,097		990,438		$ 2,049,496	$ 1,871,139
Commissions	463,442		419,951		900,302	795,711
Underwriting and policy processing	51,907		50,733		103,167	98,901
Information technology	57,669		50,599		122,454	104,089
Sales and advertising	19,781		16,954		37,156	34,161
Customer service	11,390		10,346		23,077	20,426
Administrative and other	44,091		45,619		89,874	91,236
Total operating expenses	860,924		800,230		1,698,947	1,542,119
Operating income	199,173		190,208		350,549	329,020
Total investment income	19,600		13,827		39,136	28,906
Other income	1,974		3,292		5,808	6,703
Income tax expense	46,062		43,424		82,391	76,174
Net income	174,685		163,903		313,102	288,455
Depreciation and amortization expense	16,100		13,800		31,900	27,100
Management fee revenue | Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	842,149		777,937		1,614,843	1,460,557
Administrative services reimbursement revenue
Segment Reporting Information [Line Items]
Total operating revenue	212,644		206,028		422,917	397,595
Total operating expenses	212,644		206,028		422,917	397,595
Administrative services reimbursement revenue | Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	212,644		206,028		422,917	397,595
Total operating expenses	212,644		206,028		422,917	397,595
Service agreement revenue
Segment Reporting Information [Line Items]
Total operating revenue	5,304		6,473		11,736	12,987
Service agreement revenue | Management Operations
Segment Reporting Information [Line Items]
Total operating revenue	5,304		6,473		11,736	12,987
Management fee revenue - policy issuance and renewal services
Segment Reporting Information [Line Items]
Total operating revenue	823,853		760,886		1,578,902	1,426,572
Total operating expenses	648,280		594,202		1,276,030	1,144,524
Management fee revenue - policy issuance and renewal services | Management Operations
Segment Reporting Information [Line Items]
Total operating expenses	$ 648,280		$ 594,202		$ 1,276,030	$ 1,144,524