| Label | Element | Value | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Document Type | dei_DocumentType | 485BPOS | ||||||||
| Document Period End Date | dei_DocumentPeriodEndDate | Dec. 31, 2020 | ||||||||
| Entity Registrant Name | dei_EntityRegistrantName | Putnam Convertible Securities Fund | ||||||||
| Entity Central Index Key | dei_EntityCentralIndexKey | 0000081247 | ||||||||
| Entity Inv Company Type | dei_EntityInvCompanyType | N-1A | ||||||||
| Amendment Flag | dei_AmendmentFlag | false | ||||||||
| Putnam Convertible Securities Fund | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Risk/Return [Heading] | rr_RiskReturnHeading | Fund summary | ||||||||
| Objective [Heading] | rr_ObjectiveHeading | Goal | ||||||||
| Objective, Primary [Text Block] | rr_ObjectivePrimaryTextBlock | Putnam Convertible Securities Fund seeks, with equal emphasis, current income and capital appreciation. Its secondary objective is conservation of capital. |
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| Expense [Heading] | rr_ExpenseHeading | Fees and expenses | ||||||||
| Expense Narrative [Text Block] | rr_ExpenseNarrativeTextBlock | The following tables describe the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. More information about these and other discounts is available from your financial professional and in How do I buy fund shares? beginning on page 15 of the fund’s prospectus, in the Appendix to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s statement of additional information (SAI). |
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| Shareholder Fees Caption [Text] | rr_ShareholderFeesCaption | Shareholder fees (fees paid directly from your investment) | ||||||||
| Operating Expenses Caption [Text] | rr_OperatingExpensesCaption | Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment) | ||||||||
| Portfolio Turnover [Heading] | rr_PortfolioTurnoverHeading | Portfolio turnover | ||||||||
| Portfolio Turnover [Text Block] | rr_PortfolioTurnoverTextBlock | The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs and may result in higher taxes when the fund’s shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 98%.
Prospectus 3
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| Portfolio Turnover, Rate | rr_PortfolioTurnoverRate | 98.00% | ||||||||
| Expense Breakpoint Discounts [Text] | rr_ExpenseBreakpointDiscounts | You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. | ||||||||
| Expense Breakpoint, Minimum Investment Required [Amount] | rr_ExpenseBreakpointMinimumInvestmentRequiredAmount | $ 50,000 | ||||||||
| Expense Example [Heading] | rr_ExpenseExampleHeading | Example | ||||||||
| Expense Example Narrative [Text Block] | rr_ExpenseExampleNarrativeTextBlock | The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Your actual costs may be higher or lower. |
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| Strategy [Heading] | rr_StrategyHeading | Investments, risks, and performance | ||||||||
| Strategy Narrative [Text Block] | rr_StrategyNarrativeTextBlock | Investments We invest mainly in convertible securities of U.S. companies. Under normal circumstances, we invest at least 80% of the fund’s net assets in convertible securities. This policy may be changed only after 60 days’ notice to shareholders. Convertible securities combine the investment characteristics of bonds and common stocks. Convertible securities include bonds, preferred stocks and other instruments that can be converted into or exchanged for common stock or equivalent value. A significant portion of the convertible securities we buy are below-investment-grade (sometimes referred to as “junk bonds”). The convertible bonds we buy usually have intermediate-to long-term stated maturities (i.e., three years or longer), but often contain “put” features, which allow bondholders to sell the bond back to the company under specified circumstances, that result in shorter effective maturities. When deciding whether to buy or sell investments, we may consider, among other factors: (i) a security’s structural features, such as its position in a company’s capital structure and “put” and “call” features (a company’s right to repurchase the security under specified circumstances is a “call” feature); (ii) credit and prepayment risks; and (iii) with respect to a company’s common stock underlying a convertible security, the stock’s valuation and the company’s financial strength, growth potential, competitive position in its industry, projected future earnings, cash flows and dividends. |
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| Risk [Heading] | rr_RiskHeading | Risks | ||||||||
| Risk Narrative [Text Block] | rr_RiskNarrativeTextBlock | It is important to understand that you can lose money by investing in the fund. The value of investments in the fund’s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general economic, political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, asset class, geography, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the fund’s portfolio holdings. These risks are generally greater for convertible securities issued by small and midsize companies (which may constitute a significant portion of the fund’s investments from time to time). The novel coronavirus (COVID-19) pandemic and efforts to contain its spread are likely to negatively affect the value, volatility, and liquidity of the securities and other assets in which the fund invests and exacerbate other risks that apply to the fund. These effects could negatively impact the fund’s performance and lead to losses on your investment in the fund. The value of convertible securities may be adversely affected by changes in the prices of underlying common stocks. Convertible securities tend to provide higher yields than common stocks. However, a higher yield may not protect investors against the risk of loss or adequately mitigate any loss associated with a decline in the price of a convertible security. Convertible securities are subject to credit risk, which is the risk that an issuer of the fund’s investments may default on payment of interest or principal. Credit risk is generally greater for below-investment-grade convertible
securities (a significant part of the fund’s investments). Generally, convertible securities may be less sensitive to interest rate changes than non-convertible bonds as a result of convertible securities’ convertibility and “put” features. Interest rate risk is generally greater for longer-term bonds and convertible securities whose underlying stock price has fallen significantly below the conversion price. Bond investments may be more susceptible to downgrades or defaults during economic downturns or other periods of economic stress. There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the fund will produce the intended outcome or that the investments we select for the fund will perform as well as other securities that were not selected for the fund. We, or the fund’s other service providers, may experience disruptions or operating errors that could negatively impact the fund. The fund may not achieve its goal, and it is not intended to be a complete investment program. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. |
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| Risk Lose Money [Text] | rr_RiskLoseMoney | It is important to understand that you can lose money by investing in the fund. | ||||||||
| Risk Not Insured Depository Institution [Text] | rr_RiskNotInsuredDepositoryInstitution | An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. | ||||||||
| Bar Chart and Performance Table [Heading] | rr_BarChartAndPerformanceTableHeading | Performance | ||||||||
| Performance Narrative [Text Block] | rr_PerformanceNarrativeTextBlock | The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at putnam.com. |
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| Performance Information Illustrates Variability of Returns [Text] | rr_PerformanceInformationIllustratesVariabilityOfReturns | The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. | ||||||||
| Performance Availability Website Address [Text] | rr_PerformanceAvailabilityWebSiteAddress | putnam.com | ||||||||
| Performance Past Does Not Indicate Future [Text] | rr_PerformancePastDoesNotIndicateFuture | Please remember that past performance is not necessarily an indication of future results. | ||||||||
| Bar Chart [Heading] | rr_BarChartHeading | Annual total returns for class A shares before sales charges | ||||||||
| Bar Chart Does Not Reflect Sales Loads [Text] | rr_BarChartDoesNotReflectSalesLoads | The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. | ||||||||
| Highest Quarterly Return, Label | rr_HighestQuarterlyReturnLabel | Best calendar quarter | ||||||||
| Highest Quarterly Return, Date | rr_BarChartHighestQuarterlyReturnDate | Jun. 30, 2020 | ||||||||
| Highest Quarterly Return | rr_BarChartHighestQuarterlyReturn | 25.30% | ||||||||
| Lowest Quarterly Return, Label | rr_LowestQuarterlyReturnLabel | Worst calendar quarter | ||||||||
| Lowest Quarterly Return, Date | rr_BarChartLowestQuarterlyReturnDate | Sep. 30, 2011 | ||||||||
| Lowest Quarterly Return | rr_BarChartLowestQuarterlyReturn | (14.14%) | ||||||||
| Performance Table Heading | rr_PerformanceTableHeading | Average annual total returns after sales charges (for periods ended 12/31/20) | ||||||||
| Performance Table Uses Highest Federal Rate | rr_PerformanceTableUsesHighestFederalRate | After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes. | ||||||||
| Performance Table Not Relevant to Tax Deferred | rr_PerformanceTableNotRelevantToTaxDeferred | Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. | ||||||||
| Performance Table One Class of after Tax Shown [Text] | rr_PerformanceTableOneClassOfAfterTaxShown | After-tax returns are shown for class A shares only and will vary for other classes. | ||||||||
| Performance Table Closing [Text Block] | rr_PerformanceTableClosingTextBlock | ICE BofA Indexes: ICE Data Indices, LLC (“ICE BofA”), used with permission. ICE BofA permits use of the ICE BofA indices and related data on an “as is” basis; makes no warranties regarding same; does not guarantee the suitability, quality, accuracy, timeliness, and/or completeness of the ICE BofA indices or any data included in, related to, or derived therefrom; assumes no liability in connection with the use of the foregoing; and does not sponsor, endorse, or recommend Putnam Investments, or any of its products or services. After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are shown for class A shares only and will vary for other classes. These after-tax returns do not apply if you hold your fund shares through a 401(k) plan, an IRA, or another tax-advantaged arrangement. Class B share performance reflects conversion to class A shares after eight years. |
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| Putnam Convertible Securities Fund | ICE BofA U.S. Convertible Index (no deduction for fees, expenses or taxes | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 46.22% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 17.76% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 12.59% | ||||||||
| Putnam Convertible Securities Fund | Class A | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | 5.75% | ||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | 1.00% | [1] | |||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.62% | ||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.17% | ||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 1.04% | ||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 675 | ||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 887 | ||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 1,116 | ||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 1,773 | ||||||||
| Annual Return 2011 | rr_AnnualReturn2011 | (6.47%) | ||||||||
| Annual Return 2012 | rr_AnnualReturn2012 | 15.09% | ||||||||
| Annual Return 2013 | rr_AnnualReturn2013 | 21.96% | ||||||||
| Annual Return 2014 | rr_AnnualReturn2014 | 7.47% | ||||||||
| Annual Return 2015 | rr_AnnualReturn2015 | (7.03%) | ||||||||
| Annual Return 2016 | rr_AnnualReturn2016 | 9.51% | ||||||||
| Annual Return 2017 | rr_AnnualReturn2017 | 14.93% | ||||||||
| Annual Return 2018 | rr_AnnualReturn2018 | (3.26%) | ||||||||
| Annual Return 2019 | rr_AnnualReturn2019 | 24.31% | ||||||||
| Annual Return 2020 | rr_AnnualReturn2020 | 44.97% | ||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 36.64% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 15.64% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 10.49% | ||||||||
| Putnam Convertible Securities Fund | Class A | After Taxes on Distributions | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 32.32% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 13.22% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 8.68% | ||||||||
| Putnam Convertible Securities Fund | Class A | After Taxes on Distributions and Sales | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 23.26% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 11.73% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 7.87% | ||||||||
| Putnam Convertible Securities Fund | Class B | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | 5.00% | [2] | |||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.62% | ||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.17% | ||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 1.79% | ||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 682 | ||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 863 | ||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 1,170 | ||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | 1,908 | ||||||||
| Expense Example, No Redemption, 1 Year | rr_ExpenseExampleNoRedemptionYear01 | 182 | ||||||||
| Expense Example, No Redemption, 3 Years | rr_ExpenseExampleNoRedemptionYear03 | 563 | ||||||||
| Expense Example, No Redemption, 5 Years | rr_ExpenseExampleNoRedemptionYear05 | 970 | ||||||||
| Expense Example, No Redemption, 10 Years | rr_ExpenseExampleNoRedemptionYear10 | $ 1,908 | ||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 38.90% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 15.93% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 10.49% | ||||||||
| Putnam Convertible Securities Fund | Class C | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | 1.00% | [3] | |||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.62% | ||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.17% | ||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 1.79% | ||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 282 | ||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 563 | ||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 970 | ||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | 2,105 | ||||||||
| Expense Example, No Redemption, 1 Year | rr_ExpenseExampleNoRedemptionYear01 | 182 | ||||||||
| Expense Example, No Redemption, 3 Years | rr_ExpenseExampleNoRedemptionYear03 | 563 | ||||||||
| Expense Example, No Redemption, 5 Years | rr_ExpenseExampleNoRedemptionYear05 | 970 | ||||||||
| Expense Example, No Redemption, 10 Years | rr_ExpenseExampleNoRedemptionYear10 | $ 2,105 | ||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 42.88% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 16.14% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 10.32% | ||||||||
| Putnam Convertible Securities Fund | Class R | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.62% | ||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.50% | ||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.17% | ||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 1.29% | ||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 131 | ||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 409 | ||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 708 | ||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 1,556 | ||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 44.62% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 16.73% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 10.88% | ||||||||
| Putnam Convertible Securities Fund | Class R6 | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.62% | ||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.10% | ||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 0.72% | ||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 74 | ||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 230 | ||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 401 | ||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 894 | ||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 45.41% | [4] | |||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 17.35% | [4] | |||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 11.45% | [4] | |||||||
| Putnam Convertible Securities Fund | Class Y | ||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.62% | ||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.17% | ||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 0.79% | ||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 81 | ||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 252 | ||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 439 | ||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 978 | ||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 45.33% | ||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 17.31% | ||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 11.43% | ||||||||
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