Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Cost of pension plans:
Service cost for benefits earned	$ 7,777	$ 7,050
Interest cost on benefits obligation	8,569	8,281
Expected return on plan assets	(10,317)	(9,880)
Prior service cost amortization	218	174
Net actuarial loss amortization	2,325	2,028
Pension plan cost	8,572	$ 7,653
Employee pension plan
Postretirement Benefits
Employer contribution	$ 19,000
Erie Insurance Exchange (EIE)
Postretirement Benefits
Postretirement annual benefit expense reimbursed to Indemnity from the Exchange (as a percent)	58.00%
Erie Family Life Insurance Company (EFL) \| Employee pension plan
Postretirement Benefits
Contingent liability for amount of nonparticipating annuity contracts the employee pension plan purchased from EFL	$ 20,500

Represents the percentage at which postretirement benefit expenses are reimbursed to the attorney-in-fact.

No definition available.

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- Definition

The amount of gains or losses recognized in net periodic benefit cost.

+ References

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- Definition

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

+ References

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- Definition

Amount of contributions made by the employer to defined benefit plans.

+ References

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-Publisher FASB
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The amount of estimated future defined benefit annual plan participant benefits covered by insurance contracts issued by the employer or its related parties.

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- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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No definition available.

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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