Significant Accounting Policies - Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Agent loans, allowance for credit loss		$ 1,000	$ 1,100
Receivables from Erie Insurance Exchange, allowance for credit loss		500	600
Cumulative effect adjustment		1,342,478	1,188,048			$ 1,133,253	$ 973,672
Available-for-sales securities, allowance for credit loss		$ 100	$ 200	$ 600
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	[1]					(1,075)
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Agent loans, allowance for credit loss					$ 800
Cumulative effect adjustment						$ 1,100
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment | Erie Insurance Exchange (EIE)
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 in 2020 is related to the implementation of credit loss allowance accounting guidance effective January 1, 2020. See Note 2, "Significant Accounting Policies."