Significant Accounting Policies (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019		Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Agent loans, allowance for credit loss	$ 1,000
Cumulative effect adjustment	1,194,139	$ 1,116,992		$ 1,133,253		$ 1,063,454	$ 1,013,804	$ 973,672
Available-for-sale securities, allowance for credit loss	$ 400	$ 600
Cumulative effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Agent loans, allowance for credit loss			$ 800
Cumulative effect adjustment			1,100	$ (1,075)	[1]
Erie Insurance Exchange | Cumulative effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables from Erie Insurance Exchange, allowance for credit loss			$ 600

[1] The cumulative effect adjustment is related to the implementation of new credit loss allowance accounting guidance effective January 1, 2020. See Note 2. "Significant Accounting Policies".