Name:	erie_FairValueInputsAddedForLackOfMarketability
Namespace Prefix:	erie_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The observable yield of another security with similar characteristics to the security being valued, used as an input to measure fair value.

No definition available.

Name:	erie_FairValueInputsComparableSecurityYield
Namespace Prefix:	erie_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Rate at which loans or a loan portfolio are expected to repay principal balances on maturity, used as an input to measure fair value.

No definition available.

Name:	erie_FairValueInputsRepaymentRate
Namespace Prefix:	erie_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Variable interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value.

No definition available.

Name:	erie_FairValueInputsVariableRate
Namespace Prefix:	erie_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the number of securities in the entity's investment portfolio where the determination of fair value utilizes unobservable inputs.

No definition available.

Name:	erie_NumberOfInvestmentHoldingsUnobservableInputs
Namespace Prefix:	erie_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Represents the percentage of securities using unobservable inputs as compared to the total portfolio.

No definition available.

Name:	erie_PercentageOfSecuritiesUsingUnobservableInputsToTotalPortfolio
Namespace Prefix:	erie_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_FairValueInputsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Adjustment to the discount rate used to measure fair value for lack of ability to convert business interests into cash quickly.

Name:	us-gaap_FairValueInputsDiscountForLackOfMarketability
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Market valuation of entity divided by earnings before interest, taxes, depreciation, and amortization (EBITDA), used as an input to measure fair value.

Name:	us-gaap_FairValueInputsEarningsBeforeInterestTaxesDepreciationAndAmortizationMultiple
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Price at which a dealer is willing to buy an instrument, used as an input to measure fair value.

Name:	us-gaap_FairValueInputsOfferedQuotes
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.