Represents the period of prior year actual underwriting data used to estimate agent bonuses.

No definition available.

Name:	erie_AgentBonusEstimateActualUnderwritingDataPeriod
Namespace Prefix:	erie_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period over which performance is measured for the estimation of agent bonuses.

+ References

No definition available.

+ Details

Name:	erie_AgentBonusPerformancePeriod
Namespace Prefix:	erie_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the maximum maturity period at date of purchase for an available-for-sale security to be considered a current asset.

+ References

No definition available.

+ Details

Name:	erie_AvailableforSaleSecuritiesMaximumMaturity
Namespace Prefix:	erie_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the maximum maturity period at date of purchase for an investment to be considered a cash equivalent.

+ References

No definition available.

+ Details

Name:	erie_CashEquivalentsMaximumMaturity
Namespace Prefix:	erie_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the management fee rate, determined by the board of directors of the entity, calculated as a percentage of the direct and affiliated assumed written premiums.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	erie_ScheduleOfEquityMethodInvestmentEquityMethodOwnershipPercentAxis=erie_EquityMethodInvestmentOwnershipPercentLessThan10PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=erie_ErieInsuranceExchangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Significant Accounting Policies (Details 2)	12 Months Ended
Significant Accounting Policies (Details 2)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash and cash equivalents
Cash and cash equivalents, maximum maturity at the date of purchase (in months)	3 months
Available-for-sale securities
Available-for-sale securities, maximum maturity to be classified as current assets (in months)	12 months
Software costs
Capitalized software costs, estimated useful life (in years)	7 years
Agent bonus estimates
Performance period for agent bonuses (in months)	36 months
Period of prior year actual underwriting data used to estimate agent bonuses (in years)	2 years
Less than 10%
Limited partnerships
Limited partnerships, general ownership percentage (as a percent)	10.00%
Erie Insurance Exchange (EIE)
Recognition of management fee revenue
Indemnity's maximum management fee rate as a percent of premiums written and assumed by the Exchange (as a percent)	25.00%	25.00%	25.00%