Amount of receivables arising from transactions with related parties due within one year or the normal operating cycle, if longer.

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Name:	us-gaap_AccountsReceivableRelatedPartiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Concentrations of Credit Risk (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Concentration Risk [Line Items]
Receivables from Erie Insurance Exchange and its affiliates	$ 494.6		$ 468.6
Cumulative Effect, Period of Adoption, Adjustment \| Accounting Standards Update 2016-13 \| Erie Insurance Exchange (EIE)
Concentration Risk [Line Items]
Receivables from Erie Insurance Exchange, allowance for credit loss		$ 0.6