Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Retirement Benefits [Abstract] Benefits expected to be paid over the next 10 years from pension plans: Defined Benefit Plan, Expected Future Benefit Payment [Abstract] 2019 Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 2020 Defined Benefit Plan, Expected Future Benefit Payment, Year Two 2021 Defined Benefit Plan, Expected Future Benefit Payment, Year Three 2022 Defined Benefit Plan, Expected Future Benefit Payment, Year Four 2023 Defined Benefit Plan, Expected Future Benefit Payment, Year Five 2024-2028 Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter Fair Value Disclosures [Abstract] Schedule of Fair Value Measurements on a Recurring Basis by Asset Class and Level of Input Fair Value, Assets Measured on Recurring Basis [Table Text Block] Schedule of Roll Forward of Level 3 Fair Value Measurements on a Recurring Basis Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Schedule of Fair Value Measurements on a Recurring Basis by Pricing Source Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Schedule of Carrying Value and Fair Value Estimates of Level 3 Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Schedule of Provision for Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Reconciliation of the Provision for Income Taxes, with Amounts Determined by Applying the Statutory Federal Income Tax Rate to Pre-Tax Income Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Temporary Differences and Carry-Forwards, which Give Rise to Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Unrecognized Tax Benefits Roll Forward Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Tax Status [Axis] Retirement Plan Tax Status [Axis] Retirement Plan Tax Status [Domain] Retirement Plan Tax Status [Domain] Nonqualified Plan Nonqualified Plan [Member] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Supplemental employee retirement plan (SERP) Supplemental Employee Retirement Plan [Member] Retirement Plan Funding Status [Axis] Retirement Plan Funding Status [Axis] Retirement Plan Funding Status [Domain] Retirement Plan Funding Status [Domain] Unfunded plan Unfunded Plan [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Erie Insurance Exchange (EIE) Erie Insurance Exchange [Member] Represents Erie Insurance Exchange, a Pennsylvania-domiciled reciprocal insurer that writes property and casualty insurance. Postretirement benefits Defined Benefit Plan Disclosure [Line Items] Postretirement annual benefit expense reimbursed to Indemnity from the Exchange and its subsidiaries (as a percent) Defined Benefit Plan, Postretirement Benefit (Expenses) Reimbursement Percentage Represents the percentage at which postretirement benefit expenses are reimbursed to the attorney-in-fact. Cost of pension plans: Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Service cost for benefits earned Defined Benefit Plan, Service Cost Interest cost on benefit obligation Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Prior service cost amortization Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Net actuarial loss amortization Defined Benefit Plan, Amortization of Gain (Loss) Settlement cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Pension plan cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Number of former plan participants resulting in charges recognized as settlements Defined Benefit Plan Number of Former Participants Related to Settlements The number of former plan participants for which settlement charges were recognized. Property Plant And Equipment and Finite-Lived Intangible Assets, Net By Type [Abstract] Property Plant And Equipment and Finite-Lived Intangible Assets, Net By Type [Abstract] Schedule of Property, Plant and Equipment and Finite-Lived Intangible Assets, Net by Type [Table] Schedule of Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Table] Schedule of Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Table] Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Axis] Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Axis] Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Axis] Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Domain] Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Domain] Property, Plant and Equipment and Finite-Lived Intangible Assets, Net By Type [Domain] Land, buildings, and building improvements Land, Buildings and Improvements [Member] Leasehold improvements Leasehold Improvements [Member] Software Software and Software Development Costs [Member] Equipment Vehicles And Equipment [Member] Vehicles and tangible personal property used in the creation, maintenance and utilization of information systems. Projects in progress Software Development [Member] Construction in progress Construction in Progress [Member] Fixed assets Schedule of Property, Plant and Equipment and Finite-Lived Intangible Assets, Net by Type [Line Items] [Line Items] for Schedule of Property, Plant and Equipment and Finite-Lived Intangible Assets, Net by Type [Table] Total tangible fixed assets, gross Property, Plant and Equipment, Gross Software Finite-Lived Intangible Assets, Gross Projects in progress Finite-Lived Intangible Assets, Not Yet Subject To Amortization Amount of assets, excluding financial assets and goodwill, lacking physical substance with a finite life, that are not yet subject to amortization. Total fixed assets, gross Finite Lived Intangible Assets And Property Plant And Equipment Gross Amount before amortization, accumulated depreciation and depletion, of assets, excluding financial assets and goodwill, lacking physical substance with a finite life and physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, capitalized internally developed software, land, buildings, machinery and equipment, office equipment, and furniture and fixtures. Less: Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment and Finite-Lived Intangible Assets Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services and intangible assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Fixed assets, net Finite Lived Intangible Assets And Property Plant And Equipment Net Amount after amortization, accumulated depreciation and depletion, of assets, excluding financial assets and goodwill, lacking physical substance with a finite life and physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, capitalized internally developed software, land, buildings, machinery and equipment, office equipment, and furniture and fixtures. Gain on sale of field offices Gain (Loss) on Sale of Properties Capitalized interest included in construction in progress Cumulative Interest Costs Capitalized Amount of interest capitalized inception-to-date. Depreciation and amortization expense Depreciation, Depletion and Amortization Earnings Per Share [Abstract] Schedule Of Earnings Per Share Basic And Diluted [Table] Schedule Of Earnings Per Share Basic And Diluted [Table] Disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations. Tax Cuts and Jobs Act of 2017 [Axis] Tax Cuts and Jobs Act of 2017 [Axis] Tax Cuts and Jobs Act of 2017 [Axis] Tax Cuts and Jobs Act of 2017 [Domain] Tax Cuts and Jobs Act of 2017 [Domain] Tax Cuts and Jobs Act of 2017 [Domain] Tax Cuts and Jobs Act of 2017 Tax Cuts and Jobs Act of 2017 [Member] Tax Cuts and Jobs Act of 2017 [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Class A Common Stock Common Class A [Member] Class B Common Stock Common Class B [Member] Reconciliation of the numerators and denominators used in the basic and diluted per-share computations Schedule Of Earnings Per Share Basic And Diluted [Line Items] 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. Ratio for converting shares of Class B common stock into shares of Class A common stock (as a percent) Common Stock Conversion Ratio The ratio applied to Class B common stock shares for purposes of determining the number of Class A common stock shares into which the stock will be converted (the number of Class A common stock shares into which one Class B common stock share may be converted). Effect of Tax Cuts and Jobs Act of 2017 Effect of Tax Cuts and Jobs Act of 2017 [Abstract] Effect of Tax Cuts and Jobs Act of 2017 [Abstract] Increase in income tax expense Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability Impact on basic EPS (per share) Tax Cuts and Jobs Act of 2017, Impact on Basic Earnings Per Share Amount of increase (decrease) in basic earnings per share due to the Tax Cuts and Jobs Act of 2017. Impact on diluted EPS (per share) Tax Cuts and Jobs Act of 2017, Impact on Diluted Earnings Per Share Amount of increase (decrease) in diluted earnings per share due to the Tax Cuts and Jobs Act of 2017. Income available to stockholders (Basic EPS:) Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Allocated net income (numerator) Net Income (Loss) Available to Common Stockholders, Basic Weighted shares (denominator) Weighted Average Number of Shares Outstanding, Basic Per- share amount Earnings Per Share, Basic Dilutive effect of stock-based awards Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Allocated net income (numerator) Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units Weighted shares (denominator) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Assumed conversion of Class B shares Dilutive Securities Effect on Basic Earnings Per Share Assumed Conversion [Abstract] -- None. No documentation exists for this element. -- Allocated net income (numerator) Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities Weighted shares (denominator) Incremental Common Shares Attributable to Conversion of Convertible Common Stock Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible common stock using the if-converted method. Income available to stockholders on equivalent shares (Diluted EPS:) Net Income (Loss) Attributable to Parent, Diluted [Abstract] Allocated net income (numerator) Net Income (Loss) Attributable to Parent, Diluted Weighted shares (denominator) Weighted Average Number of Shares Outstanding, Diluted Per- share amount Earnings Per Share, Diluted Deferred tax assets: Deferred Tax Assets, Gross [Abstract] Other employee benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Other Pension and other postretirement benefits Deferred Tax Assets, Tax Deferred Expense Compensation and Benefits Pensions and Postretirement Benefits The tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from pension costs and postretirement benefits, which can only be deducted for tax purposes when actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Allowance for management fee returned on cancelled policies Deferred Tax Assets, Net Allowance for Premium Cancellations The amount as of the balance sheet date of the estimated future tax effects attributable to the difference between the methods used to account for the allowance for premium cancellations for tax purposes and under generally accepted accounting principles. The difference in basis of such prepaid expenses will reduce future taxable income when such basis difference reverses. Deferred revenue Deferred Tax Assets, Deferred Income Unrealized losses on investments Deferred Tax Assets, Investments Other Deferred Tax Assets, Other Total deferred tax assets Deferred Tax Assets, Gross, Noncurrent Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Depreciation Deferred Tax Liabilities, Property, Plant and Equipment Prepaid expenses Deferred Tax Liabilities, Prepaid Expenses Commissions Deferred Tax Liabilities, Advance Commissions Amount of deferred tax liability attributable to taxable temporary differences from advance commission payments. Limited partnerships Deferred Tax Liabilities, Equity Method Investments The amount as of the balance sheet date of the estimated future tax effects attributable to the difference between the tax basis and the generally accepted accounting principles basis of a company's equity method investment which will increase future taxable income when such basis difference reverses. Unrealized gains on investments Deferred Tax Liabilities, Investments Other Deferred Tax Liabilities, Other Total deferred tax liabilities Deferred Tax Liabilities, Gross, Noncurrent Net deferred tax asset Deferred Tax Assets, Net Revenue from Contract with Customer [Abstract] Revenue, Performance Obligation [Abstract] Revenue, Performance Obligation [Abstract] Indemnity's management fee rate as a percent of premiums written and assumed by the Exchange Insurance Agency Management Fee, Percent 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. Performance obligations under subscriber's agreement Revenue, Performance Obligation, Number of Performance Obligations Number of performance obligations recognized by Indemnity acting as attorney-in-fact for the subscribers of the Exchange in accordance with Topic 606. Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Table] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Adjustments due to ASC 606 Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 Accounting Standards Update 2014-09 [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Contract liability recorded upon adoption of ASC 606 Contract with Customer, Liability Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Statement Statement [Line Items] Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Available-for-sale securities Debt Securities, Available-for-sale, Current Available-for-sale securities Available-for-sale Securities, Current Receivables from Erie Insurance Exchange and affiliates Accounts Receivable, Related Parties, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Federal income taxes recoverable Income Taxes Receivable, Current Note receivable from Erie Family Life Insurance Company Notes Receivable, Related Parties, Current Accrued investment income Accrued Investment Income Receivable Total current assets Assets, Current Available-for-sale securities Debt Securities, Available-for-sale, Noncurrent Available-for-sale securities Available-for-sale Securities, Noncurrent Equity securities Equity Securities, FV-NI Limited partnership investments Equity Method Investments Fixed assets, net Deferred income taxes, net Other assets Other Assets, Noncurrent Total assets Assets Liabilities and shareholders' equity Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Commissions payable Accrued Sales Commission, Current Agent bonuses AgentBonusesPayableCurrent Carrying value as of the balance sheet date of obligations incurred and payable for incentive compensation awarded to independent agents or earned by them based on the terms of one or more relevant arrangements. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Dividends payable Dividends Payable, Current Contract liability Contract with Customer, Liability, Current Deferred executive compensation Deferred Compensation Liability, Current Current portion of long-term borrowings Long-term Debt, Current Maturities Total current liabilities Liabilities, Current Defined benefit pension plans Liability, Defined Benefit Pension Plan, Noncurrent Contract liability Contract with Customer, Liability, Noncurrent Deferred executive compensation Deferred Compensation Liability, Classified, Noncurrent Long-term borrowings Long-term Debt, Excluding Current Maturities Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Shareholders' equity Stockholders' Equity Attributable to Parent [Abstract] Common stock Common Stock, Value, Issued Additional paid-in-capital Additional Paid in Capital, Common Stock Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total contributed capital and retained earnings Stockholders' Equity before Treasury Stock Treasury stock, at cost; 22,110,132 shares held Treasury Stock, Common, Value Deferred compensation Common Stock Issued Director Stock Trust Value of common stock issued to a trust (for example, a 'rabbi trust') set up specifically to accumulate stock for the sole purpose of distribution to participating directors. This trust does not allow directors to immediately or after a holding period diversify into nonemployer securities. The deferred compensation plan for which this trust is set up must be settled by the delivery of a fixed number of shares of employer stock. Total shareholders' equity Stockholders' Equity Attributable to Parent Total liabilities and shareholders' equity Liabilities and Equity Investments [Abstract] Schedule of Reconciliation of Cost to Fair Value of Available-For-Sale Securities Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Schedule of Amortized Cost and Estimated Fair Value of Available-For-Sale Securities by Remaining Contractual Term to Maturity Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of Available-For-Sale Securities in a Gross Unrealized Loss Position by Length of Time Schedule of Unrealized Loss on Investments [Table Text Block] Schedule of Investment Income, Net of Expenses, from Portfolios Investment Income [Table Text Block] Schedule of Realized Gains and Losses on Investments and Net Unrealized Losses Recognized during the Reporting Period Related to Equity Securities Held at the Reporting Date Realized and Unrealized Gain (Loss) on Investments [Table Text Block] Tabular disclosure of realized and unrealized gains and losses on investments reported in the statement of income. Schedule of Limited Partnership Results, Generally Reported on a One Quarter Lag Equity Method Investments [Table Text Block] Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Information [Table] Quarterly Financial Information [Table] Disclosure of the quarterly financial data in the annual financial statements. The disclosure includes financial information for each fiscal quarter for the current and previous year, including revenues, gross profit, income (loss) before extraordinary items and cumulative effect of a change in accounting principle and earnings per share data. Quarterly Results of Operations (unaudited) Quarterly Financial Information [Line Items] 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. Operating revenue Revenue from Contract with Customer, Excluding Assessed Tax Operating expenses Operating Expenses Investment income Investment Income, Nonoperating Interest expense and other (income), net Interest Expense and Other Nonoperating (Income) Expense, Net Amount of the cost of borrowed funds accounted for as interest expense, and (income) expense related to nonoperating activities, classified as other. Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Net income Net Income (Loss) Attributable to Parent Earnings Per Share Net income per share Earnings Per Share, Basic and Diluted [Abstract] Common stock - basic (in dollars per share) Common stock - diluted (in dollars per share) Accounting Policies [Abstract] Basis of presentation Basis of Accounting, Policy [Policy Text Block] Use of estimates Use of Estimates, Policy [Policy Text Block] Recent accounting standards New Accounting Pronouncements, Policy [Policy Text Block] Cash and cash equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Available-for-sale securities Marketable Securities, Policy [Policy Text Block] Limited partnerships Equity Method Investments [Policy Text Block] Deferred taxes Income Tax, Policy [Policy Text Block] Fixed assets Fixed Assets [Policy Text Block] Disclosure of accounting policy for long-lived, physical assets used in the normal conduct of business and not intended for resale, and costs incurred for software when both (1) the software is acquired, internally developed, or modified solely to meet the entity's internal needs, and (2) during the software's development or modification, no substantive plan exists or is being developed to market the software externally. Includes, but is not limited to, basis of assets, depreciation, amortization and depletion methods used, including composite deprecation, estimated useful lives, capitalization policy, accounting treatment for costs incurred for repairs and maintenance, capitalized interest and the method it is calculated, disposals and impairments. Other assets Other Assets [Policy Text Block] Disclosure of accounting policy for other assets, including loans made to independent agents. Agent bonus estimates Commissions Expense, Policy [Policy Text Block] Recognition of management fee and service agreement revenue Revenue from Contract with Customer [Policy Text Block] Administrative services Administrative Services [Policy Text Block] Disclosure of accounting policy for administrative services provided by Indemnity acting as attorney-in-fact on behalf of the Exchange, as well as a service provider for its insurance subsidiaries, with respect to all claims handling, life insurance, and investment management services. Reclassifications Reclassification, Policy [Policy Text Block] Earnings per share Earnings Per Share, Policy [Policy Text Block] Fair value of financial instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Fair value of financial instruments, transfers between levels Fair Value Transfer, Policy [Policy Text Block] Commitments and contingencies Commitments and Contingencies, Policy [Policy Text Block] Reconciliation of the provision for income taxes, with amounts determined by applying the statutory federal income tax rate to pre-tax income Effective Income Tax Rate Reconciliation, Amount [Abstract] Income tax at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Change in tax rate Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Tax-exempt interest Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Unrecognized tax benefits Unrecognized Tax Benefits, Period Increase (Decrease) Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Income tax expense Income Tax Expense (Benefit) Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Carrying values and fair value measurements of financial instruments disclosed, but not carried at fair value Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Financial assets Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Agent loans Agent Loans Represents the portion of other assets categorized as agent loans, as of the balance sheet date. Financial liabilities Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Long-term borrowings Long-term Debt Employee pension plan Pension Plan [Member] Qualified Plan Qualified Plan [Member] Funded Plan Funded Plan [Member] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Total Defined Benefit Plan, Plan Assets, Category [Domain] Total equity securities Equity Securities [Member] U.S. equity securities Us Equity Securities [Member] Ownership interest or right to acquire or dispose of ownership interest in corporations and other legal entities in the United States for which ownership interest is represented by shares of common or preferred stock, convertible securities, stock rights, or stock warrants. Non-U.S. equity securities Foreign Equity Securities [Member] Ownership interest or right to acquire or dispose of ownership interest in foreign corporations and other foreign legal entities for which ownership interest is represented by shares of common or preferred stock, convertible securities, stock rights, or stock warrants. Debt securities Debt Securities [Member] Other Money Market Funds [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Quoted prices in active markets for identical assets Level 1 Fair Value, Inputs, Level 1 [Member] Observable inputs Level 2 Fair Value, Inputs, Level 2 [Member] Unobservable inputs Level 3 Fair Value, Inputs, Level 3 [Member] Fair value measurements of pension plan assets: Total Defined Benefit Plan, Plan Assets, Amount Schedule of Impacts of Adoption of ASC 606 Schedule of Prospective Adoption of New Accounting Pronouncements [Table Text Block] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Supplemental Cash Flow Information [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization and Gain (Loss) on Disposition The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets and the amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property. Deferred income tax (benefit) expense Deferred Income Tax Expense (Benefit) Other income tax expense Realized losses (gains) and impairments on investments Realized Investment Gains (Losses) and Impairment of Investments The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, offset by the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. Equity in losses (earnings) of limited partnerships Income (Loss) from Equity Method Investments (Gain) loss on disposal of fixed assets Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Net amortization of bond premium Accretion (Amortization) of Discounts and Premiums, Investments Decrease in deferred compensation Increase (Decrease) in Deferred Compensation Limited partnership distributions Proceeds from Equity Method Investment, Distribution Increase in receivables from affiliates Increase (Decrease) in Accounts Receivable, Related Parties Decrease (increase) in accrued investment income Increase (Decrease) in Accrued Investment Income Receivable Decrease (increase) in federal income taxes recoverable Increase (Decrease) in Income Taxes Receivable (Increase) decrease in prepaid pension Increase (Decrease) in Obligation, Pension Benefits Increase in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Increase in accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Increase in commissions payable Increase (Decrease) in Reserve for Commissions, Expense and Taxes (Decrease) increase in accrued agent bonuses Increase Decrease In Accrued Agent Bonuses The increase (decrease) during the reporting period in the aggregate amount of bonus obligations related to services received from independent agents. Increase in contract liability Increase (Decrease) in Contract with Customer, Liability Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. Treasury US Treasury Securities [Member] States and political subdivisions US States and Political Subdivisions Debt Securities [Member] Foreign government securities Corporate debt securities Corporate Debt Securities [Member] Residential mortgage-backed securities Residential Mortgage Backed Securities [Member] Commercial mortgage-backed securities Commercial Mortgage Backed Securities [Member] Collateralized debt obligations Collateralized Debt Obligations [Member] Other debt securities Other Debt Obligations [Member] Nonredeemable preferred stock Nonredeemable Preferred Stock [Member] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Domain] External Credit Rating by Grouping [Domain] Investment grade External Credit Rating, Investment Grade [Member] Non-investment grade External Credit Rating, Non Investment Grade [Member] Industry Sector [Axis] Industry Sector [Axis] Industry Sector [Domain] Industry Sector [Domain] Financial Services Sector Financial Services Sector [Member] Utilities Sector Utilities Sector [Member] Sector of the economy consisting of companies engaged in utilities. Available-for-sale securities Debt Securities, Available-for-sale [Line Items] Fair value Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract] Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 12 months or longer Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 12 months or longer Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Total Debt Securities, Available-for-sale, Unrealized Loss Position Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Unrealized losses Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 12 months or longer Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 12 months or longer Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Total Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss No. of holdings Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions No. of holdings Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Class of Stock Disclosures [Abstract] Capital Stock Stock by Class [Text Block] The entire disclosure of an entity's stock (includes common, convertible, and preferred stocks), including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock including , and, the entire disclosure for an entity's treasury stock, including the average cost per share, carrying basis for each class of treasury stock, description of share repurchase program authorized by an entity's board of directors, the number of shares repurchased, the cost of the shares repurchased, the remaining maximum dollar value of shares available for repurchase under the program, the treatment of the purchase price in excess of the current market value, number of shares held for each class of treasury stock and other information necessary to a fair presentation, and EPS information. Related Party Transactions [Abstract] Related Party Related Party Transactions Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common stock Common Stock [Member] Additional paid-in-capital Additional Paid-in Capital [Member] Accumulated other comprehensive income (loss) AOCI Attributable to Parent [Member] Retained earnings Retained Earnings [Member] Treasury stock Treasury Stock [Member] Deferred compensation Deferred Compensation [Member] Deferred compensation arrangement (such as stock or unit options and share or unit awards) that is equity-based payments with participants. The arrangement is based on an agreement between the entity and the participant, and contains a promise by the entity to pay certain amounts or benefits at designated future dates, upon compliance with stipulated requirements. Increase (decrease) in shareholders' equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, end of year Cumulative effect adjustments Cumulative Effect of New Accounting Principle in Period of Adoption Other comprehensive (loss) income Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Dividends declared: Dividends, Common Stock, Cash Net purchase of treasury stock Net Treasury Stock Value Acquired Held And Reissued Equity impact of the cost of common stock that was repurchased under a publicly announced share repurchase program and equity impact of common stock repurchased, held, or reissued during the period for any equity-based compensation plan, recorded using the cost method. Deferred compensation Deferred Compensation Under Rabbi Trust Plans Deferred compensation under rabbi trust plans that represents the value of common stock issued to the rabbi trust set up specifically to accumulate stock for the sole purpose of distribution to participants, which is part of stockholders' equity. Rabbi trust distribution Distributions From Rabbi Trust Plans Distributions of common stock from the rabbi trust to participants. AOCI reclassification Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Net of Tax Amount, net of tax, of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017. Balance, end of year Schedule of Disaggregation of Revenue by Performance Obligation Disaggregation of Revenue [Table Text Block] U.S. small capitalization core equity Us Small Capitalization Core Equity [Member] This category includes U.S. equity securities that seek to achieve excess returns relative to the Russell 2000 Index while maintaining portfolio risk characteristics similar to the index. U.S. equity index Us Equity Index [Member] This category comprises U.S. equity index funds not actively managed that track the S&P 500. International small capitalization risk controlled equity International Small Capitalization Risk Controlled Equity [Member] This category seeks to provide excess returns relative to an international small cap index, while maintaining regional weights similar to the index. International emerging markets equity Emerging Markets Equity [Member] This category seeks long-term capital growth in securities of companies that have their principal business activities in countries in the Morgan Stanley Capital International Emerging Markets Free Index. International risk controlled equity International Risk Controlled Equity [Member] This category seeks long-term capital growth with an emphasis on controlling return volatility relative to an international market index. U.S. Treasury Strips U.S. corporate bonds with an emphasis on long duration bonds rated A or better Debt Security, Corporate, US [Member] Floating rate high income leverage loans Target asset allocation for the portfolio: Defined Benefit Plan, Plan Assets, Allocations [Abstract] Total plan assets (as a percent) Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Actual asset allocation for the portfolio: Defined Benefit Plan, Information about Plan Assets [Abstract] Total plan assets (as a percent) Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Revenue Revenue from Contract with Customer [Text Block] Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Supplementary Data on Cash Flows Cash Flow, Supplemental Disclosures [Text Block] Schedule of Gain (Loss) on Securities [Table] Schedule of Gain (Loss) on Securities [Table] Available-for-sale securities Equity securities Other investments Miscellaneous Investments [Member] Accounting Standards Update 2016-01 Accounting Standards Update 2016-01 [Member] Realized (losses) gains on investments Gain (Loss) on Securities [Line Items] Gross realized gains Debt Securities, Available-for-sale, Realized Gain Gross realized losses Debt Securities, Available-for-sale, Realized Loss, Excluding Other-than-temporary Impairment Net realized (losses) gains on available-for-sale securities Debt Securities, Available-for-sale, Realized Gain (Loss), Excluding Other-than-temporary Impairment Net losses recognized during the period Equity Securities, FV-NI, Gain (Loss) Less: net losses recognized on securities sold Equity Securities, FV-NI, Realized Loss Net unrealized losses recognized on securities held at reporting date Equity Securities, FV-NI, Unrealized Gain (Loss) Common stock trading securities Trading Securities, Realized Gain (Loss) Other Realized Investment Gains (Losses) Net realized investment (losses) gains Gain (Loss) on Investments, Excluding Other than Temporary Impairments New Accounting Pronouncements New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Cumulative effect of adopting ASU 2016-01 New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets Other-than-temporary impairments on investments Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale [Abstract] Other-than-temporary impairments on available-for-sale securities recognized in earnings Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Recognized in Earnings Other-than-temporary impairments on available-for-sale securities recognized in other comprehensive income Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Portion in Other Comprehensive Loss, before Tax, Including Portion Attributable to Noncontrolling Interest Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Method Of Accounting [Axis] Method Of Accounting [Axis] Information by method of accounting. Method Of Accounting [Domain] Method Of Accounting [Domain] Various methods of accounting under generally accepted accounting practices. Fair value option Fair Value Option [Member] The fair vale option permits entities to choose, at specified election dates, to measure eligible items at fair value (the “fair value option”), the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A business entity shall report unrealized gains and losses on items for which the fair value option has been elected in earnings (or another performance indicator if the business entity does not report earnings) at each subsequent reporting date. Upfront costs and fees related to items for which the fair value option is elected shall be recognized in earnings as incurred and not deferred. Private equity Private Equity Funds [Member] Mezzanine debt Mezzanine Funds [Member] Investments held in mezzanine funds. Real estate Real Estate Funds [Member] Investment in limited partnerships Schedule of Equity Method Investments [Line Items] Asset recorded Schedule of Cost of Pension Plans Schedule of Net Benefit Costs [Table Text Block] Schedule of Actuarial Assumptions Used to Measure the Year-End Obligations and Net Periodic Benefit Costs for the Subsequent Year Schedule of Assumptions Used [Table Text Block] Schedule of Funded Status of Pension Plans and Amounts Recognized in the Statements of Financial Position Schedule of Net Funded Status And Amounts Recognized In Balance Sheet [Table Text Block] Tabular disclosure of net funded status of pension plans and/or other employee benefit plans and tabular disclosure of the amounts that are recognized in the balance sheet (or statement of financial position) for pension plans and/or other employee benefit plans, showing separately the assets and current and noncurrent liabilities (if applicable) recognized. Schedule of Reconciliation of Beginning and Ending Balances of the Projected Benefit Obligation, as well as the Accumulated Benefit Obligation Schedule of Accumulated and Projected Benefit Obligations [Table Text Block] Schedule of Defined Benefit Pension Plans with Assets less than Projected Benefit Obligation Schedule of Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block] Schedule of Defined Benefit Pension Plans with Assets less than Accumulated Benefit Obligation Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block] Schedule of Reconciliation of Beginning and Ending Balances of the Fair Value of Plan Assets Schedule of Changes in Fair Value of Plan Assets [Table Text Block] Schedule of Amounts Included in Accumulated Other Comprehensive Income that were Not Yet Recognized as Components of Net Benefit Costs Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block] Schedule of Amounts Recognized in Other Comprehensive Income for Pension Plans Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Schedule of Target and Actual Asset Allocations for the Portfolio Schedule of Target and Actual Allocations of Plan Assets [Table Text Block] Tabular disclosure of the target and actual allocations of the major categories of plan assets of pension plans and/or other employee benefit plans. Schedule of Fair Value Measurements of Pension Plan Assets by Major Category and Level of Input Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Benefits Expected to be Paid Over the Next 10 Years from Pension Plans Schedule of Expected Benefit Payments [Table Text Block] Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component, Including Amounts Reclassified to Other Comprehensive Income (Loss) and the Related Line item in the Statements of Operations Where Net Income is Presented Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Equity Method Investments and Joint Ventures [Abstract] Equity method of accounting Equity Method Of Accounting [Member] An accounting method used by entities to assess the profits earned by investments in other companies. The entity reports the income earned on the investment on its income statement and the reported value is based on the entity's share of the company assets. The reported profit is proportional to the size of the equity investment. This is the standard method used when one company has significant influence over another. Number of real estate limited partnerships that do not meet the criteria of an investment company Number of Real Estate Properties Equity in (losses) earnings of limited partnerships Postretirement Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Amounts recognized in other comprehensive income for pension plans: Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract] Net actuarial (gain) loss arising during the year Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Amortization of prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Amendments Other Comprehensive Income Defined Benefit Plans Amendments During Period before Tax Amount, before tax, of other comprehensive income from plan amendments, that has not been recognized in net periodic benefit cost. Impact due to settlement Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax Total recognized in other comprehensive income Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Number of new plan participants resulting in charges recognized as amendments Defined Benefit Plan Number of New Plan Participants Related to Amendments The number of new plan participants for which amendment charges were recognized. Impact of amendments on pension obligation Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Impact of amendments on prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax Statement of Comprehensive Income [Abstract] Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Change in unrealized holding (losses) gains on available-for-sale securities Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Pension and other postretirement plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent OCI (loss) Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Debt Disclosure [Abstract] Borrowing Arrangements Debt Disclosure [Text Block] Treasury stock (in shares) Treasury Stock, Common, Shares Common stock, stated value per share (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, authorized (in shares) Common Stock, Shares Authorized Common stock, issued (in shares) Common Stock, Shares, Issued Common stock, outstanding (in shares) Common Stock, Shares, Outstanding Foreign government securities Debt Security, Government, Non-US [Member] Amortized cost Debt Securities, Available-for-sale, Amortized Cost Amortized cost Available-for-sale Equity Securities, Amortized Cost Basis Amortized cost Available-for-sale Securities, Amortized Cost Basis Gross unrealized gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Gross unrealized gains Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax Gross unrealized gains Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Gross unrealized losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Gross unrealized losses Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax Gross unrealized losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Estimated fair value Debt Securities, Available-for-sale Estimated fair value Available-for-sale Securities, Equity Securities Estimated fair value Available-for-sale Securities Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Management fee revenue, policy issuance and renewal services Policy Issuance and Renewal Services [Member] Policy issuance and renewal services provided by Indemnity that result in executed insurance policies between the Exchange or one of its insurance subsidiaries and the subscriber (policyholder). Management fee revenue, administrative services Administrative Services Management Fee [Member] Administrative services provided by Indemnity acting as attorney-in-fact on behalf of the Exchange, as well as a service provider for its insurance subsidiaries, with respect to all claims handling, life insurance, and investment management services. Administrative services reimbursements Administrative Services Reimbursements [Member] Administrative services expenses, which are expenses incurred by Indemnity acting as attorney-in-fact on behalf of the Exchange, as well as a service provider for its insurance subsidiaries, with respect to all claims handling, life insurance, and investment management services. Administrative services Administrative Services [Member] Revenue allocated to administrative services, which includes two components: (1) management fee revenue allocated to the administrative services Indemnity provides acting as attorney-in-fact on behalf of the Exchange and its property and casualty insurance subsidiaries with respect to all claims handling and investment management services, as well as the service provider for all life insurance and investment management services for Erie Family Life Insurance Company; and (2) the revenue recorded for the reimbursement of the administrative services expenses. Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Transferred at point in time Transferred at Point in Time [Member] Transferred over time Transferred over Time [Member] Disaggregation of revenue by performance obligation Disaggregation of Revenue [Line Items] Gross management fee revenue recognized Revenue from Contract with Customer, Excluding Assessed Tax, Gross Amount, excluding tax collected from customer and before change in premium cancellation allowance, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. Investments Investments in Debt and Equity Instruments, Cash and Cash Equivalents, Unrealized and Realized Gains (Losses) [Text Block] Compensation Related Costs [Abstract] Incentive and Deferred Compensation Plans Disclosure Of Compensation Related Costs, Cash Based Incentive And Share Based Payments And Deferred Compensation [Text Block] The entire disclosure for compensation-related costs for cash-based incentive and share/equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of compensation, incentive distributions, compensation arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details, employee stock purchase plan details, and income statement compensation items. Deferred compensation arrangements may include a description of an arrangement with an individual employee, which is generally an employment contract between the entity and a selected officer or key employee containing a promise by the employer to pay certain amounts at designated future dates, usually including a period after retirement, upon compliance with stipulated requirements. This type of arrangement is distinguished from broader based employee benefit plans as it is usually tailored to the employee. Disclosure also typically includes the amount of related compensation expense recognized during the reporting period, the number of shares (units) issued during the period under such arrangements, and the carrying amount as of the balance sheet date of the related liability. Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Level 3 Investment Secondary Categorization [Axis] Investment Secondary Categorization [Axis] Investments by Secondary Categorization [Domain] Investments by Secondary Categorization [Domain] Available-for-sale securities Available-for-sale Securities [Member] Level 3 changes Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Roll forward of level 3 fair value measurements on a recurring basis Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Included in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Included in other comprehensive income Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Transfers into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Transfers out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Ending balance Change in unrealized gains or losses included in other comprehensive income related to Level 3 securities held at the reporting date Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI [Abstract] Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI [Abstract] Net unrealized losses on Level 3 securities held at reporting date Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3) and still held. Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Common stock Class of Stock [Line Items] Number of classes of common stock Number Of Classes Of Common Stock Number Of Classes Of Common Stock Minimum multiplier for dividend payable on Class A common stock per dividend declared on Class B common stock (as a percent) Dividends Common Stock Percentage Multiplier Minimum Represents the minimum multiplier applied to a percentage of the dividend declared on Class B common stock to determine the required dividend on Class A common stock. Percentage of dividend declared on Class B common stock used to determine dividend payable on Class A common stock (as a percent) Dividends Common Stock Percentage Represents the percentage of the dividend declared on Class B common stock to which a multiplier is applied to determine the required dividend on Class A common stock. Ratio for converting shares of Class B common stock into shares of Class A common stock (as a percent) Class B common stock shares converted into Class A common stock shares (in shares) Conversion of Stock, Shares Converted Investment Income [Table] Investment Income [Table] Erie Family Life Insurance Company (EFL) Erie Family Life Insurance Company [Member] Represents Erie Family Life Insurance Company ("EFL"), an affiliated life insurance company that underwrites and sells individual and group life insurance policies and fixed annuities, wholly owned by the Erie Insurance Exchange. Investment Type [Axis] Investment Type [Axis] Investment Type Categorization [Domain] Investments [Domain] Fixed maturities Cash equivalents and other Cash and Cash Equivalents [Member] Investment income from portfolios Net Investment Income [Line Items] Total investment income Interest and Dividend Income, Operating Less: investment expenses Investment Income, Investment Expense Investment income, net of expenses Net Investment Income Note receivable from EFL, interest income recognized by Indemnity Interest Income, Related Party Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Quarterly Results of Operations (unaudited) Quarterly Financial Information [Text Block] Fair Value Fair Value Disclosures [Text Block] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] Stock repurchase program Share Repurchase Program 1999 [Member] A stock repurchase program was authorized by the company's board of directors for the purchase of its outstanding Class A nonvoting common stock beginning January 1, 1999. These shares are recorded as Treasury shares in the company's statements of financial position at total cost based upon trade date. Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Equity compensation plan Equity Compensation Plan [Member] Represents the entity's equity compensation plan, which is designed to reward key employees, as determined by the entity's compensation committee or the chief executive officer, who can have a significant impact on the entity's long-term performance and to further align the interests of such employees with those of the entity's shareholders. The equity compensation plan permits grants of restricted shares, restricted share units and other share based awards, to be satisfied with shares of the entity's Class A common stock or cash. Stock compensation plan for outside directors Stock Compensation Plan Outside Directors [Member] Represents the entity's stock compensation plan for outside directors, which is a plan to further align the interests of the directors with those of the entity's shareholders that provides for a portion of the directors' annual compensation in shares of the entity's Class A common stock. Upon ending board service, directors are paid shares of our Class A common stock equal to the number of share credits in their deferred stock account. Incentive compensation deferral plan Incentive Compensation Deferral Plan [Member] Represents the entity's incentive compensation deferral plan, which is a plan where participants can defer up to 100% of their annual or long-term incentive plan award. Deferred awards are credited to deferred stock account as credits denominated in Class A shares of the Company stock. Long-term incentive plan Long Term Incentive Plan [Member] Represents the entity's long-term incentive plan, which is a performance based incentive plan designed to reward the entity's executive and senior vice presidents who can have a significant impact on the entity's long-term performance and to further align the interests of such employees with those of the entity's shareholders. The long-term incentive plan permits grants of performance shares or units, to be satisfied with shares of the entity's Class A common stock or cash payment as determined by the compensation committee. Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Performance shares Performance Shares [Member] Stock repurchases Equity, Class of Treasury Stock [Line Items] Shares repurchased under stock repurchase program (in shares) Treasury Stock, Shares, Acquired Amount of authorized stock repurchases approved for continuation under the current program Stock Repurchase Program, Authorized Amount Approximate amount of repurchase authority remaining under the current stock repurchase program Stock Repurchase Program, Remaining Authorized Repurchase Amount Shares purchased outside of stock repurchase program Share-based Compensation [Abstract] Shares purchased outside of publicly announced stock repurchase program for share-based compensation awards Share-based Compensation Arrangement by Share-based Payment Award, Shares Purchased for Award Total cost of shares purchased outside of publicly announced stock repurchase program Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid Average price per share for shares purchased Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted Average Price of Shares Purchased Commitments and Contingencies Disclosure [Abstract] Other Commitments [Table] Other Commitments [Table] Contractual commitments to invest in limited partnership investments Other Commitments [Line Items] Represents the entity's maximum contractual commitments to invest in its limited partnership investments Other Commitment Fixed Assets Property, Plant, and Equipment and Intangible Assets [Text Block] Schedule of Defined Contribution Plans Disclosures [Table] Schedule of Defined Contribution Plans Disclosures [Table] Schedule of Defined Contribution Plans Disclosures [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Defined Contribution Plans [Axis] Defined Contribution Plans [Axis] Defined Contribution Plans [Axis] Defined Contribution Plans [Domain] Defined Contribution Plans [Domain] [Domain] for Defined Contribution Plans [Axis] 100% employer matching contribution One Hundred Percent Match [Member] A 100 percent match of the provided unit. 50% employer matching contribution Fifty Percent Match [Member] A 50 percent match of the provided unit. Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Minimum Minimum [Member] Employee savings plan Schedule of Defined Contribution Plans Disclosures [Line Items] [Line Items] for Schedule of Defined Contribution Plans Disclosures [Table] Percentage of employer matching contribution of employee contributions (as a percent) Defined Contribution Plan, Employer Matching Contribution, Percent of Match Percentage of eligible employee compensation, matched by employer (as a percent) Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Employer matching contribution paid to the plan Defined Contribution Plan, Cost Employer discretionary contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Matching contributions reimbursed to Indemnity from the Exchange and its subsidiaries (as a percent) Defined Contribution Plan, Matching Contributions Reimbursement Percentage Represents the percentage at which 401(k) matching contributions are reimbursed to the attorney-in-fact. Class A common stock held by plan participants (in shares) Defined Contribution Plan Number of Equity Securities Issued by Employer and Related Parties Included in Plan Assets The number of employer shares or related party shares included in the defined contribution plan assets. Employer contributions during fiscal year Defined Benefit Plan, Plan Assets, Contributions by Employer Minimum target normal cost threshold necessary for future pension funding Defined Benefit Plan, Target Normal Cost Threshold Minimum target normal cost threshold necessary for future pension funding. Funding target (as a percentage of the funding target liability) Defined Benefit Plan, Funding Target Percentage Plan assets of a defined benefit plan, as a percentage of the funding target liability as defined by the Pension Protection Act of 2006. Net amount recognized in the Statements of Financial Position: Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract] Funded status at end of year Defined Benefit Plan, Funded (Unfunded) Status of Plan Pension liabilities - due within one year Liability, Defined Benefit Pension Plan, Current Pension liabilities - due after one year Net amount recognized Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position Projected benefit obligation: Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Projected benefit obligation, beginning of year Defined Benefit Plan, Benefit Obligation Plan amendments Actuarial (gain) loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Settlement cost Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement Projected benefit obligation, end of year Accumulated benefit obligation, end of year Defined Benefit Plan, Accumulated Benefit Obligation Projected benefit obligations decrease Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease) Discount rate used to measure future benefit obligations Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Plans with assets less than projected benefit obligations Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract] Projected benefit obligation Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation Plan assets Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets Plans with assets less than accumulated benefit obligations Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract] Accumulated benefit obligation Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation Plan assets Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Investment securities: Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Pension and other postretirement plans: Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Total Changes in accumulated other comprehensive income (loss) by component, including amounts reclassified to other comprehensive income (loss) and the related line item in the Statements of Operations where net income is presented Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated other comprehensive income (loss), before tax AOCI Attributable to Parent [Abstract] AOCI (loss), beginning of year AOCI before Tax, Attributable to Parent OCI (loss) before reclassifications - pre TCJA Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax OCI before reclassifications - post TCJA Tax Cuts and Jobs Act of 2017, Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Amount before tax and reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities remeasured pursuant to the Tax Cuts and Jobs Act of 2017. Realized investment losses (gains) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Impairment losses Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax Cumulative effect of adopting ASU 2016-01, before tax Cumulative Effect on Retained Earnings, before Tax Investment securities, OCI (loss) Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent OCI (loss) before reclassifications Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax Amortization of prior service costs Amortization of net actuarial loss Settlement loss Pension and other postretirement plans, OCI (loss) Other Comprehensive (Income) Loss, Defined Benefit Plan, before Tax, after Reclassification Adjustment, Attributable to Parent OCI (loss) Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent AOCI (loss), end of year Accumulated other comprehensive income (loss), tax AOCI Attributable to Parent, Tax [Abstract] AOCI Attributable to Parent, Tax [Abstract] AOCI (loss), beginning of year AOCI Tax, Attributable to Parent OCI (loss) before reclassifications - pre TCJA Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax OCI before reclassifications - post TCJA Tax Cuts and Jobs Act of 2017, Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities remeasured pursuant to the Tax Cuts and Jobs Act of 2017. Realized investment losses (gains) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Impairment losses Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, Tax Cumulative tax effect of adopting ASU 2016-01 Cumulative Effect on Retained Earnings, Tax Investment securities, OCI (loss) Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax OCI (loss) before reclassifications Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, Tax Amortization of prior service costs Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax Settlement loss Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax Impact of change in tax rate Tax Cuts and Jobs Act of 2017, Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Attributable to Parent Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent, remeasured pursuant to the Tax Cuts and Jobs Act of 2017. Pension and other postretirement plans, OCI (loss) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Attributable to Parent Reclassification adjustment Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Amount of tax of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017. OCI (loss) Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent AOCI (loss), end of year Accumulated other comprehensive income (loss), net of tax AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI (loss), beginning of year OCI (loss) before reclassifications - pre TCJA Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax OCI before reclassifications - post TCJA Tax Cuts and Jobs Act of 2017, Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities remeasured pursuant to the Tax Cuts and Jobs Act of 2017. Realized investment losses (gains) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Impairment losses Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, Net of Tax Cumulative effect of adopting ASU 2016-01, net of tax Cumulative Effect on Retained Earnings, Net of Tax Investment securities, OCI (loss) OCI (loss) before reclassifications Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax Amortization of prior service costs Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Settlement loss Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax Impact of change in tax rate Tax Cuts and Jobs Act of 2017, Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent, remeasured pursuant to the Tax Cuts and Jobs Act of 2017. Pension and other postretirement plans, OCI (loss) Reclassification adjustment AOCI (loss), end of year Schedule of Reconciliation of Net Income to Net Cash Provided by Operating Activities as Presented in the Statements of Cash Flows Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Schedule of Quarterly Results of Operations (Unaudited) Quarterly Financial Information [Table Text Block] Schedule of Deferred Executive and Outside Directors' Compensation Liability Schedule Of Compensation Cost For Cash Based Incentive And Share Based Payments And Deferred Compensation, Allocation Of Costs By Plan [Table Text Block] Tabular disclosure of the amount of total cash-based incentive plan compensation cost, share/equity-based compensation cost, and deferred compensation arrangements, including the amounts related to awards, payments, deferrals, liabilities, and any tax benefits attributable to each plan. Schedule of Reconciliation of the Numerators and Denominators Used in the Basic and Diluted Per-Share Computations Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Line of Credit Facility [Table] Line of Credit Facility [Table] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Line of Credit Revolving Credit Facility [Member] Bank line of credit Line of Credit Facility [Line Items] Maximum borrowing capacity under the bank revolving line of credit Line of Credit Facility, Maximum Borrowing Capacity Maximum letter of credit sublimit under the bank revolving line of credit Letters Of Credit Maximum, Amount The maximum letters of credit capcity under the credit facility as of the reporting date. Available borrowing capacity under the bank revolving line of credit, due to outstanding letters of credit Line of Credit Facility, Current Borrowing Capacity Outstanding amount of letters of credit sublimit under the bank revolving line of credit Letters of Credit Outstanding, Amount Available amount of letters of credit sublimit under the bank revolving line of credit Letters Of Credit Available, Amount The available amount of letters of credit less the amount of the contingent obligation under letters of credit outstanding under the credit facility as of the reporting date. Borrowings outstanding under the bank revolving line of credit Long-term Line of Credit Fair value of bonds pledged as collateral on the bank revolving line of credit Security Owned and Pledged as Collateral, Fair Value Contractual Obligation, Fiscal Year Maturity Schedule [Abstract] Contractual Obligation, Fiscal Year Maturity Schedule [Abstract] Amortized cost Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after ten years Debt Securities, Available-for-sale, Allocated and Single Maturity Date, Maturity, after 10 Years, Amortized Cost Estimated fair value Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Estimated fair value Schedule of Maturity of $100 Million Credit Facility Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Incentive Plans and Deferred Compensation [Table] Schedule of Incentive Plans and Deferred Compensation [Table] Schedule of awards, payments, deferrals and liabilities under the entity's incentive and deferred compensation plans. Annual incentive plan Annual Incentive Plan [Member] Represents the entity's annual incentive plan, which is a bonus plan that pays cash to the entity's executive and senior vice presidents annually based upon attainment of corporate and individual performance measures, which can include various financial measures. Deferred compensation plans and stock compensation plan for outside directors Deferred Compensation Plan And Stock Compensation Plan Outside Directors [Member] Represents the entity's combined deferred compensation plans and stock compensation plan for outside directors. The entity's deferred compensation plans, which are arrangements for the entity's executive and senior vice presidents and outside directors that allows participants to elect to defer receipt of a portion of their compensation until a later date. The deferred compensation plan for the entity's outside directors allows participants to defer receipt of a portion of their director and meeting fees until a later date. The entity's stock compensation plan for outside directors, which is a plan to further align the interests of the directors with those of the entity's shareholders that provides for a portion of the directors' annual compensation in shares of the entity's Class A common stock. Upon ending board service, directors are paid shares of our Class A common stock equal to the number of share credits in their deferred stock account. Incentive and deferred compensation plans Incentive Plans and Deferred Compensation [Line Items] 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. Deferred executive and outside directors' compensation liability Incentive Plans And Deferred Compensation [Roll Forward] A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. Annual incentive plan awards Other Labor-related Expenses Long-term incentive plan awards Allocated Share-based Compensation Expense, Gross Represents the gross expense, before forfeitures, recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Employer match and hypothetical earnings on deferred compensation Deferred Compensation Arrangement with Individual, Compensation Expense Total plan awards and earnings Incentive Plans and Deferred Compensation Total Awards and Earnings The amount of expense recognized in income during the period arising from cash-based incentives, share/equity-based compensation plans, and deferred compensation arrangements, with employees, directors and potentially certain consultants qualifying for treatment as employees. Total plan awards paid Incentive Plan Compensation Total Liabilities Paid The liabilities paid during the accounting period for cash-based incentive and share/equity-based compensation plans, with employees, directors, and potentially certain consultants qualifying for treatment as employees. Compensation deferred Deferred Compensation Arrangement with Individual Liability Incurred During Period The liability incurred during the period to an individual under a deferred compensation arrangement. This amount may be the result of periodic accruals made over the period of active employment, or reflect termination benefits resulting contractual terms or a death benefit. Distributions from the deferred compensation plans Deferred Compensation Arrangement with Individual, Distribution Paid Forfeitures Compensation Arrangement with Individual, Forfeitures The amount of compensation forfeited by the individual during the period. Funding of rabbi trust Deferred Compensation Equity Rabbi Trust Value of stock issued under share-based plans to outside directors which is the unearned portion, accounted for under the fair value method. Incentive plan and deferred compensation liabilities at end of period Accrued Bonuses And Deferred Compensation Liability, Current And Noncurrent The carrying amount of the liability as of the balance sheet date of obligations incurred and payable for incentive compensation awarded to employees and directors or earned by them based on the terms of one or more relevant arrangements, and to an individual under a deferred compensation arrangement. This amount may be the result of periodic accruals made over the period of active employment, or reflect termination benefits resulting from contractual terms or a death benefit. Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Period of time over which management fee revenue allocated to administrative services will be recognized (in years) Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Accounting Policies [Table] Accounting Policies [Table] Specific details of accounting policies, including the line items affected and the financial effects of those policies. Accounting Standards Update 2018-02 Accounting Standards Update 2018-02 [Member] Accounting Standards Update 2018-02 Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. Balances without ASC 606 Calculated under Revenue Guidance in Effect before Topic 606 [Member] Schedule of Equity Method Investment Equity Method Ownership Percent [Axis] Schedule of Equity Method Investment Equity Method Ownership Percent [Axis] Represents the categorization of equity by ownership percentage. Equity Method Investment Ownership Percent [Domain] Equity Method Investment Ownership Percent [Domain] Represents the categories of percentages of ownership in equity method investees. Less than 10% Equity Method Investment Ownership Percent Less Than 10 Percent [Member] Represents the category of equity method investees in which the entity has less than 10% ownership. Buildings and building improvements Building and Building Improvements [Member] Accounting Policies [Line Items] Accounting Policies [Line Items] 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. Decrease in accumulated other comprehensive income and increase in retained earnings due to ASU 2018-02 Cumulative effect adjustment Impact of adoption on our Statement of Financial Position and Operations Revenue, Initial Application Period Cumulative Effect Transition [Abstract] Deferred tax asset Contract liability Management fee revenue, gross Less: change in allowance for management fee returned on cancelled policies Revenue from Contract with Customer, Excluding Assessed Tax, Premium Cancellation Allowance Amount, excluding tax collected from customer, of adjustment to revenue for the change in the estimated allowance to reduce the management fee to its estimated net realizable value to account for the potential of mid-term policy cancellations based on historical cancellation rates, from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. Operating revenue Cash and cash equivalents Cash and Cash Equivalents [Abstract] Cash and cash equivalents, maximum maturity at the date of purchase (in months) Cash Equivalents Maximum Maturity Represents the maximum maturity period at date of purchase for an investment to be considered a cash equivalent. Available-for-sale securities Debt Securities, Available-for-sale [Abstract] Available-for-sale securities, maximum maturity to be classified as current assets (in months) Available for Sale Securities Maximum Maturity Represents the maximum maturity period at date of purchase for an available-for-sale security to be considered a current asset. Limited partnerships General ownership percentage of limited partnerships (as a percent) Equity Method Investment, Ownership Percentage Fixed assets Estimated useful life (in years) Finite-Lived Intangible Asset, Useful Life Estimated useful life (in years) Property, Plant and Equipment, Useful Life Agent bonus estimates Selling, General and Administrative Expense [Abstract] Performance period for agent bonuses (in months) Agent Bonus Performance Period Represents the period over which performance is measured for the estimation of agent bonuses. Period of prior year actual underwriting data used to estimate agent bonuses (in years) Agent Bonus Estimate Actual Underwriting Data, Period Represents the period of prior year actual underwriting data used to estimate agent bonuses. Administrative services Cash settlements Reimbursements Received from Related Party Represents reimbursements received from a related party. Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Statement of Cash Flows [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related party transaction Related Party Transaction [Line Items] Cash flows from operating activities Management fee received Proceeds from Insurance Agency Management Fees Received Cash received for management fees during the current period. Administrative services reimbursements received Administrative Services Reimbursements Received Administrative Services Reimbursements Received Service agreement fee received Proceeds from Fees Received Net investment income received Proceeds from Interest and Dividends Received (Decrease) increase in reimbursements collected from affiliates Increase (Decrease) in Due from Related Parties, Current Commissions paid to agents Payments for Commissions Agents bonuses paid Payments For Agent Bonuses The amount of cash paid for agent bonuses during the current period. Salaries and wages paid Payments to Employees Pension contributions and employee benefits paid Pension Contributions and Payments for Other Labor Related Expenses Payments of cash for pension contributions, payroll tax expense, postemployment and benefit-related expenses not elsewhere specified in the taxonomy (such as health plan, profit sharing, incentives, tuition reimbursement, other fringe benefits and perquisites) during the current period. General operating expenses paid Payments for Other Operating Activities Administrative services expenses paid Administrative Services Expenses Paid Administrative Services Expenses Paid Income taxes paid Income Taxes Paid, Net Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Purchase of investments: Payments to Acquire Investments [Abstract] Available-for-sale securities Payments to Acquire Debt Securities, Available-for-sale Available-for-sale securities Payments to Acquire Available-for-sale Securities Equity securities Payments to Acquire Marketable Securities Limited partnerships Payments to Acquire Limited Partnership Interests Proceeds from investments: Proceeds from Sale, Maturity and Collection of Investments [Abstract] Available-for-sale securities sales Proceeds from Sale of Debt Securities, Available-for-sale Available-for-sale securities sales Proceeds from Sale of Available-for-sale Securities Available-for-sale securities maturities/calls Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Equity securities Proceeds from Sale and Maturity of Marketable Securities Trading securities Proceeds from Sale of Debt and Equity Securities, FV-NI, Held-for-investment Limited partnerships Proceeds from Limited Partnership Investments Purchase of fixed assets Payments to Acquire Productive Assets Proceeds from disposal of fixed assets Proceeds from Sale of Productive Assets Distributions on agent loans Payments to Acquire Loans Receivable Collections on agent loans Proceeds from Collection of Loans Receivable Repayment of note receivable from Erie Family Life Insurance Repayment of Notes Receivable from Related Parties Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Dividends paid to shareholders Payments of Ordinary Dividends, Common Stock Net proceeds from long-term borrowings Proceeds from (Repayments of) Secured Debt Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of year Cash and cash equivalents, end of year Supplemental disclosure of noncash transactions Noncash Investing and Financing Items [Abstract] Transfer of investments from limited partnerships to trading securities Transfer Between Investment Categories Value of investments transferred between the entity's investments in noncash transactions. Liability incurred to purchase fixed assets Liabilities Assumed Schedule of Fixed Assets by Category Schedule of Property Plant and Equipment and Finite-Lived Intangible Assets, Net [Table Text Block] Schedule of Property Plant and Equipment and Finite-Lived Intangible Assets, Net Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Secured Debt Secured Debt [Member] Term loan credit facility Debt Instrument [Line Items] Amount of senior secured draw term loan credit facility Debt Instrument, Face Amount Scheduled draws on the credit facility Proceeds from Issuance of Debt Total amount drawn on the credit facility Secured Debt Repayment period of credit facility Debt Instrument, Term Fixed interest rate of credit facility Debt Instrument, Interest Rate, Stated Percentage Quarterly commitment fee on the unused portion of the credit facility Debt Instrument Commitment Fee Percent The fee, expressed as a percentage of the credit facility, for the unused portion of the credit facility. Fair value of bonds pledged as collateral on the credit facility Debt Instrument, Collateral Amount Principal payments due in 2019 Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year Principal payments due in 2020 Long-term Debt, Maturities, Repayments of Principal in Year Two Principal payments due in 2021 Long-term Debt, Maturities, Repayments of Principal in Year Three Principal payments due in 2022 Long-term Debt, Maturities, Repayments of Principal in Year Four Principal payments due in 2023 Long-term Debt, Maturities, Repayments of Principal in Year Five Principal payments due after 2023 Long-term Debt, Maturities, Repayments of Principal after Year Five Risks and Uncertainties [Abstract] Concentrations of Credit Risk Concentration Risk Disclosure [Text Block] Total plan Incentive Plan by Performance Period [Axis] Incentive Plan by Performance Period [Axis] Information pertaining to the entity's incentive plans, by the period over which performance is measured to determine the award. Incentive Plan Performance Period [Domain] Incentive Plan Performance Period [Domain] Identification of the period over which performance is measured to determine awards under the entity's incentive plans. Performance Period Long-Term Incentive Plan 2016-2018 Performance Period Long Term Incentive Plan 2016 To 2018 [Member] Represents the 2016-2018 performance period under the entity's Long-Term Incentive Plan. Performance Period Long-Term Incentive Plan 2015-2017 Performance Period Long Term Incentive Plan 2015 To 2017 [Member] Represents the 2015-2017 performance period under the entity's Long-Term Incentive Plan. Performance Period Long-Term Incentive Plan 2014-2016 Performance Period Long Term Incentive Plan 2014 To 2016 [Member] Represents the 2014-2016 performance period under the entity's Long-Term Incentive Plan. Performance Period Equity Compensation Plan 2014-2015 Performance Period Equity Compensation Plan 2014-2015 [Member] Represents the 2014-2015 performance period under the entity's Equity Compensation Plan. Performance Period Equity Compensation Plan 2014 Performance Period Equity Compensation Plan 2014 [Member] Represents the 2014 performance period under the entity's Equity Compensation Plan. Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Three Month Vesting Period Three Month Vesting Period [Member] For the entity's stock compensation plan for outside directors, each director vests in the grant 25% every three months over the course of a year. Number of incentive plans for executives, senior vice presidents and other selected officers Number of Executive Incentive Plans Represents the Company's number of incentive plans for executives, senior vice presidents and other selected officers. Number of deferred compensation plans for executives, senior vice presidents and other selected officers Number of Executive Deferred Compensation Plans Represents the Company's number of deferred compensation plans for executives, senior vice presidents and other selected officers. Number of deferred compensation plans for outside directors Number of Director Deferred Compensation Plans Represents the Company's number of deferred compensation plans for directors. Maximum percentage of employee compensation that can be deferred Incentive Compensation, Maximum Annual Contributions Per Employee, Percent Maximum percentage of employee compensation the employee may defer under a deferred compensation plan of the Company. Vesting period of performance and/or service condition(s) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Maximum number of shares authorized for grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Maximum number of shares which may be received by any single participant during any specified period Share Based Compensation Arrangement by Share Based Payment Award, Maximum Number of Shares Per Employee Per Specified Period The maximum number of shares that may be earned by any single participant during any specified period, which may be a specified performance period or calendar year, net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. Maximum dollar amount which may be received by any single participant during any specified period Incentive Plan Maximum Compensation Expense Per Employee Per Specified Period The maximum amount of expense that may be earned by any single participant during any specified period, which may be a specified performance period or calendar year, arising from incentive plan compensation arrangements, other than share-based awards, with employees, directors and potentially certain consultants qualifying for treatment as employees. Compensation cost related to share-based compensation plan awards Allocated Share-based Compensation Expense Average price per share for shares delivered Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted Average Price of Shares Delivered The weighted average share price for shares delivered to participants under the plan. Tax benefits recognized in income related to award expense Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Incentive plan compensation cost reimbursed to Indemnity from the Exchange and its subsidiaries (as a percent) Incentive Plans, Compensation Cost Reimbursement Percentage Represents the percentage at which incentive plan costs are reimbursed to the parent company. Total unrecognized compensation cost related to share-based compensation plan awards pertaining to open performance periods Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Expected period of recognition related to unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Vesting percent of the grant in Class A common stock Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Payment period for vested share credits Payment Period For Vested Share Credits Period over which vested share credits will be paid upon separation from service. Organization, Consolidation and Presentation of Financial Statements [Abstract] Expense Classification [Table] Expense Classification [Table] Describes the nature and type of expenses and the percentage that those expenses are to total expenses. Expense Classification [Axis] Expense Classification [Axis] Information by nature and type of expense. Expense Classification [Domain] Expense Classification [Domain] Represents the nature and type of expenses. Agent compensation expense Agent Compensation Expense [Member] Scheduled commissions to agents based upon premiums written as well as additional commissions and bonuses to agents, which are earned by achieving targeted measures. Underwriting and policy processing expense Underwriting Expense [Member] Underwriting and policy processing services provided. Information technology expense Information Technology Expense [Member] Information technology services that support all functions. Nature of expense as a percentage of total policy issuance and renewal expenses Expense Classification [Line Items] 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. Nature of expense as a percentage of total policy issuance and renewal expenses Percentage of Total Expenses Represents the nature and type of expense as a percentage of total expenses. Document and Entity Information [Abstract] -- None. No documentation exists for this element. -- Entry Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Public Float Entity Public Float Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Concentrations of credit risk from unsecured receivables Concentration Risks, Types, No Concentration Percentage [Abstract] Receivables from Erie Insurance Exchange and its subsidiaries Actuarial assumptions used to determine benefit obligations: Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] Discount rate Pre-retirement discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation Pre Retirement Discount Rate The pre-retirement interest rate used to adjust for the time value of money for the plan. Post-retirement discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation Post Retirement, Discount Rate The post-retirement interest rate used to adjust for the time value of money for the plan. Compensation increases Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Actuarial assumptions used to determine net periodic benefit cost: Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Pre-retirement discount rate Defined Benefit Plan, Assumptions Used Calculating, Net Periodic Benefit Cost, Pre Retirement Discount Rate The pre-retirement interest rate used to adjust for the time value of money. Post-retirement discount rate Defined Benefit Plan, Assumptions Used Calculating, Net Periodic Benefit Cost, Post Retirement Discount Rate The post-retirement interest rate used to adjust for the time value of money. Expected return on assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Basis Fair Value, Measurements, Recurring [Member] Fair value option using net asset value (NAV) Fair Value Measured at Net Asset Value Per Share [Member] Fair value measurements on a recurring basis by asset class and level of input Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Available-for-sale debt securities Other limited partnership investments Alternative Investment Available-for-sale equity securities Total available-for-sale securities Total Investments, Fair Value Disclosure Other limited partnership investments: Other Investments [Abstract] Contributions made to the funds Distributions received from the funds Unfunded commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Number of real estate funds reported under the fair value option Amounts included in accumulated other comprehensive income Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract] Net actuarial loss Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Prior service cost Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Net amount not yet recognized Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Nature of Operations Nature of Operations [Text Block] Schedule of provision for income taxes Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Current income tax expense Current Income Tax Expense (Benefit) Valuation Allowance [Abstract] Valuation Allowance [Abstract] Deferred tax asset valuation allowance Deferred Tax Assets, Valuation Allowance Reconciliation of unrecognized tax benefits Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Balance at the beginning of the year Unrecognized Tax Benefits Additions for current year tax positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Reductions for current year tax positions Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions Additions for prior year tax positions Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Reductions for prior year tax positions Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Balance at the end of the year Tax expense related to uncertain tax positions Effective income tax rate change as a result of tax law change (percent) Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Current liability for uncertain tax position Liability for Uncertainty in Income Taxes, Current Interest expense related to uncertain tax positions Unrecognized Tax Benefits, Interest on Income Taxes Expense Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] Related party transactions Minimum number of affiliates to be classified as an insurance holding company system Insurance Holding Company System, Minimum Affiliates Minimum number of affiliates to be defined as an insurance holding company system. Minimum number of insurer affiliates to be classified as an insurance holding company system Insurance Holding Company System, Minimum Affiliate Insurers Minimum number of insurer affiliates to be defined as an insurance holding company system. Rent expense on office space leased from Exchange Operating Leases, Rent Expense Operating expenses on office space leased from Exchange Operating Costs and Expenses Reimbursements from the Exchange for rent and related operating expenses Rent Reimbursed from Related Party Represents rent expense reimbursed from Erie Insurance Exchange and Erie Family Life. Annual rentals paid to EFL Payments for Rent Number of field office facilities leased from the Exchange Number Of Field Office Facilities Leased From Related Party Represents the number of field office facilities leased from related parties. Note receivable from EFL Note receivable from EFL, annual interest rate (as a percent) Related Party Transaction, Rate Dividends declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Level 1 Level 2 Fair Value Measurements, Fair Value Pricing Sources [Axis] Fair Value Measurements, Fair Value Pricing Sources [Axis] Fair value information by pricing source. Fair Value Measurements, Fair Value Pricing Sources [Domain] Fair Value Measurements, Fair Value Pricing Sources [Domain] Provides the categories of pricing sources used to value financial assets and liabilities measured at fair value. Priced via pricing services Pricing Services [Member] Represents the source of fair value measurement as a nationally recognized pricing service. Priced via market comparables/broker quotes MarketComparablesBrokerQuote [Member] Represents the source of fair value measurement as broker quotes and/or market comparables which are generally used when a price from the pricing service is not available. Priced via unobservable inputs Unobservable Inputs [Member] Represents the source of fair value measurement as unobservable inputs. Fair value measurements on a recurring basis, valuation techniques Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair value by pricing source Fair Value by Pricing Source [Abstract] -- None. No documentation exists for this element. -- Fair value of plan assets: Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Fair value of plan assets, beginning of year Actual (loss) gain on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Employer contributions Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Settlements Defined Benefit Plan, Plan Assets, Payment for Settlement Fair value of plan assets, end of year Income Statement [Abstract] Service agreement revenue Service Agreement [Member] Service charges we collect from subscribers/policyholders for providing extended payment terms on policies written and assumed by the Exchange, and late payment and policy reinstatement fees. The service charges are fixed dollar amounts per billed installment. Operating revenue Revenues [Abstract] Operating expenses Operating Expenses [Abstract] Operating income Operating Income (Loss) Investment income Investment Income, Nonoperating [Abstract] Net investment income Net realized investment (losses) gains Net impairment losses recognized in earnings Total investment income Interest expense, net Interest Expense Other income (expense) Other Nonoperating Income (Expense) Income tax expense Net income Weighted average shares outstanding – Basic Weighted Average Number of Shares Outstanding, Basic [Abstract] Common stock - basic (in shares) Weighted average shares outstanding – Diluted Weighted Average Number of Shares Outstanding, Diluted [Abstract] Common stock - diluted (in shares) Earnings Per Share Earnings Per Share [Text Block]