Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	PIONEER FUND
Prospectus Date	rr_ProspectusDate	May 01, 2022
Pioneer Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund summary
Objective [Heading]	rr_ObjectiveHeading	<span style="color:#000000;font-family:Arial;font-size:11pt;font-weight:bold;">Investment objectives</span>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Reasonable income and capital growth.
Expense [Heading]	rr_ExpenseHeading	<span style="color:#000000;font-family:Arial;font-size:11pt;font-weight:bold;">Fees and expenses of the fund</span>
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that 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 or your family invest, or agree to invest in the future, at least $50,000 in Class A shares of the Pioneer funds. More information about these and other discounts is available from your investment professional and in the “Sales charges” section of the prospectus beginning on page 45, the “Intermediary defined sales charge waiver policies” section of the prospectus beginning on page 83, and the “Sales charges” section of the statement of additional information beginning on page 53. If you invest in Class K shares or Class Y shares through an investment professional or financial intermediary, that investment professional or financial intermediary may charge you a commission. Such commissions, if any, are not charged by the fund and are not reflected in the fee table or expense example below.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	<span style="color:#000000;font-family:Arial;font-size:9pt;font-weight:bold;">Shareowner fees</span> <br/><span style="color:#000000;font-family:Arial;font-size:9pt;">(fees paid directly from your investment)</span>
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<span style="color:#000000;font-family:Arial;font-size:9pt;font-weight:bold;">Annual fund operating expenses</span> <br/><span style="color:#000000;font-family:Arial;font-size:9pt;">(expenses that you pay each year as a percentage of the value of your investment)</span>
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	<span style="font-family:Arial;font-size:8pt;">May 1, </span><span style="font-family:Arial;font-size:8pt;">2023</span>
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<span style="color:#000000;font-family:Arial;font-size:11pt;font-weight:bold;">Portfolio turnover</span>
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 89% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	89.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See “Sales charges.”
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	<span style="font-family:Times New Roman;font-size:10pt;">You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $</span><span style="font-family:Times New Roman;font-size:10pt;">50,000</span><span style="font-family:Times New Roman;font-size:10pt;"> in Class A shares of the Pioneer funds.</span>
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	<span style="color:#000000;font-family:Arial;font-size:9pt;font-weight:bold;">Example</span>
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the fund for the time periods shown and then, except as indicated, redeem all of your shares at the end of those periods. It also assumes that (a) your investment has a 5% return each year and (b) the fund's total annual operating expenses remain the same except for year one (which considers the effect of the expense limitation). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	<span style="font-family:Arial;font-size:7pt;font-weight:bold;">If you redeem your shares</span><span style="font-family:Arial;font-size:7pt;font-weight:bold;">Number of years you own your shares</span>
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	<span style="font-family:Arial;font-size:7pt;font-weight:bold;">If you do not redeem your shares</span><span style="font-family:Arial;font-size:7pt;font-weight:bold;">Number of years you own your shares</span>
Strategy [Heading]	rr_StrategyHeading	<span style="color:#000000;font-family:Arial;font-size:11pt;font-weight:bold;">Principal investment strategies</span>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The fund invests in a broad group of carefully selected securities that the fund's adviser believes are reasonably priced, rather than in securities whose prices reflect a premium resulting from their current market popularity. The fund invests predominantly in equity securities. For purposes of the fund's investment policies, equity securities include common stocks and other equity instruments, such as securities of other investment companies (including mutual funds, exchange-traded funds and closed-end funds) that invest primarily in equity securities, equity interests in real estate investment trusts (REITs), depositary receipts, warrants, rights and preferred stocks.The fund primarily invests in securities of U.S. issuers. The fund may invest up to 15% of its total assets in securities of non-U.S. issuers. The fund will not invest more than 5% of its total assets in the securities of emerging markets issuers.The fund may invest up to 15% of its net assets in REITs.The fund may invest in initial public offerings of equity securities. The fund may also invest in investment grade and below investment grade debt securities (known as “junk bonds”).The fund may, but is not required to, use derivatives. The fund may use derivatives, such as stock index futures and options, for a variety of purposes, including: in an attempt to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates; as a substitute for purchasing or selling securities; to attempt to increase the fund's return as a non-hedging strategy that may be considered speculative; to manage portfolio characteristics; and as a cash flow management technique. The fund may choose not to make use of derivatives for a variety of reasons, and any use may be limited by applicable law and regulations. The fund may also hold cash or other short-term investments.The fund's investment adviser uses a value approach to select the fund's investments to buy and sell. Using this investment style and environmental, social and corporate governance (ESG) analysis described below, the adviser seeks securities selling at reasonable prices or substantial discounts to their underlying values and then holds these securities until the market values reflect their intrinsic values. The adviser evaluates a security's potential value, including the attractiveness of its market valuation, based on the company's assets and prospects for earnings growth. In making that assessment, the adviser employs fundamental research and an evaluation of the issuer based on its financial statements and operations. In selecting securities, the adviser considers a security's potential to provide a reasonable amount of income. The adviser focuses on the quality and price of individual issuers.The adviser integrates ESG analysis into its investment process by focusing on companies with sustainable business models and evaluating ESG-related risks as part of its research recommendations. In addition, the adviser generally excludes corporate issuers that do not meet or exceed minimum ESG standards, based on a system that uses ESG ratings provided by third parties or internal sources. When using ESG ratings to exclude corporate issuers and evaluating ESG issues generally, the adviser considers ratings in the context of an issuer’s respective sector or industry. The fund generally will not invest in companies significantly involved in certain business activities, including but not limited to, the production of alcohol, tobacco products and certain controversial military weapons, and the operation of thermal coal mines and gambling casinos and other gaming businesses.
Risk [Heading]	rr_RiskHeading	<span style="color:#000000;font-family:Arial;font-size:11pt;font-weight:bold;">Principal risks of investing in the fund</span>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	You could lose money on your investment in the fund. As with any mutual fund, there is no guarantee that the fund will achieve its objectives.Market risk. The market prices of securities or other assets held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, recessions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets, the spread of infectious illness or other public health issues, armed conflict, market disruptions caused by tariffs, trade disputes, sanctions or other government actions, or other factors or adverse investor sentiment. If the market prices of the fund's securities and assets fall, the value of your investment will go down. A change in financial condition or other event affecting a single issuer or market may adversely impact securities markets as a whole. Rates of inflation have recently risen. The value of assets or income from an investment may be worth less in the future as inflation decreases the value of money. As inflation increases, the real value of the fund’s assets can decline as can the value of the fund’s distributions.In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars, terror attacks and economic sanctions); measures to address budget deficits; downgrading of sovereign debt; changes in oil and commodity prices; changes in currency exchange rates; global pandemics; and public sentiment. The global pandemic of the novel coronavirus respiratory disease designated COVID-19 has resulted in major disruption to economies and markets around the world, including the United States. Global financial markets have experienced extreme volatility and severe losses, and trading in many instruments has been disrupted. Liquidity for many instruments has been greatly reduced for periods of time. Some sectors of the economy and individual issuers have experienced particularly large losses. These circumstances may continue for an extended period of time, and may continue to affect adversely the value and liquidity of the fund’s investments. Following Russia’s recent invasion of Ukraine, Russian securities have lost all, or nearly all, their market value. Other securities or markets could be similarly affected by past or future geopolitical or other events or conditions.Governments and central banks, including the U.S. Federal Reserve, have taken extraordinary and unprecedented actions to support local and global economies and the financial markets. These actions have resulted in significant expansion of public debt, including in the U.S. The consequences of high public debt, including its future impact on the economy and securities markets, may not be known for some time. Interest rates are very low, which means there is more risk that they may go up. In some cases yields are negative. U.S. Federal Reserve or other U.S. or non-U.S. governmental or central bank actions, including increases or decreases in interest rates, or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and these and other events affecting global markets, such as the United Kingdom’s exit from the European Union (or Brexit), potential trade imbalances with China, or other countries, or sanctions or other government actions against Russia, other nations or individuals or companies (or their countermeasures), may contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the implications for market participants, may not be fully known for some time.Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, armed conflict including Russia's military invasion of Ukraine, terrorism, natural disasters, infectious illness or public health issues, cybersecurity events, supply chain disruptions, sanctions against Russia, other nations or individuals or companies and possible countermeasures, and other circumstances in one country or region could have profound impacts on other countries or regions and on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries or regions directly affected, the value and liquidity of the fund’s investments may be negatively affected. The fund may experience a substantial or complete loss on any security or derivative position.Value style risk. The prices of securities the adviser believes are undervalued may not appreciate as expected or may go down. Value stocks may fall out of favor with investors and underperform the overall equity market.Portfolio selection risk. The adviser's judgment about a particular security or issuer, or about the economy or a particular sector, region, market segment or industry, or about an investment strategy, may prove to be incorrect or may not produce the desired results, or there may be imperfections, errors or limitations in the models, tools and data used by the adviser.ESG risk. The fund’s adviser considers ESG factors in making investment decisions. Excluding specific issuers limits the universe of investments available to the fund as compared with other funds that do not consider ESG factors, which may mean forgoing some investment opportunities available to funds that do not consider ESG factors. Accordingly, the fund may underperform other funds that do not utilize an investment strategy that considers ESG factors. However, the strategy of seeking to identify companies with sustainable business models is believed to provide potential return and risk benefits, including the selection of issuers with fewer ESG-related risks. Further, in implementing its ESG approach, the adviserfocuses on investment considerations that relate to potential return and risk, without sacrificing these considerations for non-economic purposes. In considering ESG factors, the fund’s adviser may use third party ESG ratings information that it believes to be reliable, but such information may not be accurate or complete, or may be biased.Risks of investments in real estate related securities. Investments in real estate securities are affected by economic conditions, interest rates, governmental actions and other factors. In addition, investing in REITs involves unique risks. They are significantly affected by the market for real estate and are dependent upon management skills and cash flow. REITs may have lower trading volumes and may be subject to more abrupt or erratic price movements than the overall securities markets. Mortgage REITs are particularly subject to interest rate and credit risks. In addition to its own expenses, the fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests. Many real estate companies, including REITs, utilize leverage.Risks of warrants and rights. If the price of the underlying stock does not rise above the exercise price before the warrant expires, the warrant generally expires without any value and the fund loses any amount it paid for the warrant. The failure to exercise subscription rights to purchase common shares would result in the dilution of the fund’s interest in the issuing company.Preferred stocks risk. Preferred stocks may pay fixed or adjustable rates of return. Preferred stocks are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s preferred stocks generally pay dividends only after the company makes required payments to holders of its bonds and other debt. Thus, the value of preferred stocks will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects. The market value of preferred stocks generally decreases when interest rates rise. Preferred stocks of smaller companies may be more vulnerable to adverse developments than preferred stocks of larger companies.Risks of initial public offerings. Companies involved in initial public offerings (IPOs) generally have limited operating histories, and prospects for future profitability are uncertain. The market for IPO issuers has been volatile, and share prices of newly public companies have fluctuated significantly over short periods of time. The purchase of IPO shares may involve high transaction costs.Risks of investment in other funds. Investing in other investment companies, including exchange-traded funds (ETFs) and closed-end funds, subjects the fund to the risks of investing in the underlying securities or assets held by those funds. When investing in another fund, the fund will bear a pro rata portion of the underlying fund’s expenses, including management fees, in addition to its own expenses. ETFs and closed-end funds are bought and sold based on market prices and can trade at a premium or a discount to the ETF’s or closed-end fund’s net asset value.Debt securities risk. Factors that could contribute to a decline in the market value of debt securities in the fund include rising interest rates, if the issuer or other obligor of a security held by the fund fails to pay principal and/or interest, otherwise defaults or has its credit rating downgraded or is perceived to be less creditworthy or the credit quality or value of any underlying assets declines. A general rise in interest rates could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the fund. Junk bonds have a higher risk of default or are already in default and are considered speculative.Risks of non-U.S. investments. Investing in non-U.S. issuers, or in U.S. issuers that have significant exposure to foreign markets, may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced for issuers in emerging markets or to the extent that the fund invests significantly in one region or country. These risks may include different financial reporting practices and regulatory standards, less liquid trading markets, extreme price volatility, currency risks, changes in economic, political, regulatory and social conditions, military conflicts and sanctions, terrorism, sustained economic downturns, financial instability, reduction of government or central bank support, inadequate accounting standards, tariffs, tax disputes or other tax burdens, nationalization or expropriation of assets, arbitrary application of laws and regulations or lack of rule of law, and investment and repatriation restrictions. Lack of information and less market regulation also may affect the value of these securities. Withholding and other non-U.S. taxes may decrease the fund’s return. Non-U.S. issuers may be located in parts of the world that have historically been prone to natural disasters. Emerging market economies tend to be less diversified than those of more developed countries. They typically have fewer medical and economic resources than more developed countries and thus they may be less able to control or mitigate the effects of a pandemic. Investing in depositary receipts is subject to many of the same risks as investing directly in non-U.S. issuers. Depositary receipts may involve higher expenses and may trade at a discount (or premium) to the underlying security.A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties. In addition, the United Kingdom has withdrawn from the EU (commonly known as “Brexit”). Other countries may seek to withdraw from the EU and/or abandon the euro, the common currency of the EU. The range and potential implications of possible political, regulatory, economic, and market outcomes of Brexit cannot be fully known but could be significant, potentially resulting in increased volatility, illiquidity and potentially lower economic growth in the affected markets, which will adversely affect the fund's investments.Sanctions or other government actions against certain countries could negatively impact the fund’s investments in securities that have exposure to those countries. Circumstances that impact one country could have profound impacts on other countries and on global economies or markets. China and other developing market countries may be subject to considerable degrees of economic, political and social instability. In addition, the U.S. government has imposed restrictions on U.S. investor participation in certain Chinese investments. These matters could adversely affect China’s economy.Russia launched a large-scale invasion of Ukraine on February 24, 2022. In response to the military action by Russia, various countries, including the U.S., the United Kingdom, and European Union, issued broad-ranging economic sanctions against Russia and Belarus and certain companies and individuals. Since then, Russian securities have lost all, or nearly all, their market value, and many other issuers, securities and markets have been adversely affected. The United States and other countries may impose sanctions on other countries, companies and individuals in light of Russia’s military invasion. The extent and duration of the military action or future escalation of such hostilities, the extent and impact of existing and future sanctions, market disruptions and volatility, and the result of any diplomatic negotiations cannot be predicted. These and any related events could have a significant impact on the value and liquidity of certain fund investments, on fund performance and the value of an investment in the fund, particularly with respect to securities and commodities, such as oil and natural gas, as well as other sectors with exposure to Russian issuers or issuers in other countries affected by the invasion, and are likely to have collateral impacts on market sectors globally.Market segment risk. To the extent the fund emphasizes, from time to time, investments in a market segment, the fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation than a fund without the same focus.Industries in the technology segment, such as information technology, communications equipment, computer hardware and software, and office and scientific equipment, are generally subject to risks of rapidly evolving technology, short product lives, rates of corporate expenditures, falling prices and profits, competition from new market entrants, and general economic conditions.Derivatives risk. Using stock index futures and options and other derivatives can increase fund losses and reduce opportunities for gains when market prices, interest rates, currencies or the derivative instruments themselves behave in a way not anticipated by the fund. Using derivatives may increase the volatility of the fund's net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the fund. Some derivatives have the potential for unlimited loss, regardless of the size of the fund’s initial investment. Derivatives are generally subject to the risks applicable to the assets, rates, indices or other indicators underlying the derivative. Changes in a derivative’s value may not correlate well with the referenced asset or metric. The fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. Use of derivatives may have different tax consequences for the fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to shareholders. The U.S. government and foreign governments are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets.Leveraging risk. The value of your investment may be more volatile and other risks tend to be compounded if the fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the fund's underlying assets and creates a risk of loss of value on a larger pool of assets than the fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations or meet segregation requirements.Valuation risk. The sales price the fund could receive for any particular portfolio investment may differ from the fund’s valuation of the investment, particularly for illiquid securities and securities that trade in thin or volatile markets or that are valued using a fair value methodology. These differences may increase significantly and affect fund investments more broadly during periods of market volatility. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the fund had not fair-valued the securities or had used a different valuation methodology. The fund’s ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers.Liquidity risk. Some securities and derivatives held by the fund may be or become impossible or difficult to purchase, sell or unwind, particularly during times of market turmoil. Illiquid securities and derivatives also may be difficult to value. If the fund is forced to sell an illiquid asset or unwind a derivatives position to meet redemption requests or other cash needs, the fund may be forced to sell at a loss.Redemption risk. The fund may experience heavy redemptions that could cause the fund to liquidate its assets at inopportune times or at a loss or depressed value, which could cause the value of your investment to decline.Cybersecurity risk. Cybersecurity failures by and breaches of the fund’s adviser, transfer agent, distributor, custodian, fund accounting agent or other service providers may disrupt fund operations, interfere with the fund’s ability to calculate its NAV, prevent fund shareholders from purchasing, redeeming or exchanging shares or receiving distributions, cause loss of or unauthorized access to private shareholder information, and result in financial losses to the fund and its shareholders, regulatory fines, penalties, reputational damage, or additional compliance costs.Expense risk. Your actual costs of investing in the fund may be higher than the expenses shown in “Annual fund operating expenses” for a variety of reasons. For example, expense ratios may be higher than those shown if overall net assets decrease. Net assets are more likely to decrease and fund expense ratios are more likely to increase when markets are volatile.Please note that there are many other factors that could adversely affect your investment and that could prevent the fund from achieving its goals.An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">You could lose money on your investment in the fund.</span>
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</span>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<span style="color:#000000;font-family:Arial;font-size:11pt;font-weight:bold;">The fund's past performance</span>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Standard & Poor’s 500 Index, a broad-based measure of market performance that has characteristics relevant to the fund’s investment strategies.You can obtain updated performance information by visiting https://www.amundi.com/usinvestors/Products/Mutual-Funds or by calling 1-800-225-6292.The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Standard & Poor’s 500 Index, a broad-based measure of market performance that has characteristics relevant to the fund’s investment strategies.</span>
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">1-800-225-6292</span>
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">https://www.amundi.com/usinvestors/Products/Mutual-Funds</span>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.</span>
Bar Chart [Heading]	rr_BarChartHeading	<span style="color:#000000;font-family:Arial;font-size:9pt;font-weight:bold;">Annual return Class A shares (%)</span><span style="color:#000000;font-family:Times New Roman;font-size:10pt;">(Year ended December 31)</span>
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.</span>
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	For the period covered by the bar chart:ReturnsPeriod BeginningPeriod EndingHighest Calendar Quarter19.92%04/01/2020 to06/30/2020Lowest Calendar Quarter–16.62%01/01/2020 to03/31/2020
Performance Table Heading	rr_PerformanceTableHeading	<span style="color:#000000;font-family:Arial;font-size:9pt;font-weight:bold;">Average annual total return (%)</span><span style="font-family:Times New Roman;font-size:10pt;">(for periods ended December 31, 2021)</span>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.</span>
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.</span>
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R and Class Y shares will vary.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R and Class Y shares will vary.
Pioneer Fund | A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.67%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.14%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.06%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Net Expenses	rr_NetExpensesOverAssets	1.06%	[2]
1	rr_ExpenseExampleYear01	$ 677
3	rr_ExpenseExampleYear03	893
5	rr_ExpenseExampleYear05	1,126
10	rr_ExpenseExampleYear10	1,795
1	rr_ExpenseExampleNoRedemptionYear01	677
3	rr_ExpenseExampleNoRedemptionYear03	893
5	rr_ExpenseExampleNoRedemptionYear05	1,126
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,795
2012	rr_AnnualReturn2012	9.90%
2013	rr_AnnualReturn2013	33.06%
2014	rr_AnnualReturn2014	10.87%
2015	rr_AnnualReturn2015	(0.43%)
2016	rr_AnnualReturn2016	9.60%
2017	rr_AnnualReturn2017	21.54%
2018	rr_AnnualReturn2018	(1.74%)
2019	rr_AnnualReturn2019	31.00%
2020	rr_AnnualReturn2020	23.90%
2021	rr_AnnualReturn2021	27.81%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	<span style="font-family:Arial;font-size:8pt;margin-left:0.0pt;">Highest Calendar Quarter</span>
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	19.92%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	<span style="font-family:Arial;font-size:8pt;margin-left:0.0pt;">Lowest Calendar Quarter</span>
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn
1 Year	rr_AverageAnnualReturnYear01	20.45%
5 Years	rr_AverageAnnualReturnYear05	18.48%
10 Years	rr_AverageAnnualReturnYear10	15.24%
InceptionDate	rr_AverageAnnualReturnInceptionDate	Feb. 13, 2028
Pioneer Fund | C
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.67%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.83%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Net Expenses	rr_NetExpensesOverAssets	1.83%	[2]
1	rr_ExpenseExampleYear01	$ 286
3	rr_ExpenseExampleYear03	576
5	rr_ExpenseExampleYear05	990
10	rr_ExpenseExampleYear10	2,148
1	rr_ExpenseExampleNoRedemptionYear01	186
3	rr_ExpenseExampleNoRedemptionYear03	576
5	rr_ExpenseExampleNoRedemptionYear05	990
10	rr_ExpenseExampleNoRedemptionYear10	$ 2,148
1 Year	rr_AverageAnnualReturnYear01	25.79%
5 Years	rr_AverageAnnualReturnYear05	18.95%
10 Years	rr_AverageAnnualReturnYear10	15.02%
InceptionDate	rr_AverageAnnualReturnInceptionDate	Jul. 01, 2096
Pioneer Fund | K
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.67%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.06%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.73%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.12%	[2]
Net Expenses	rr_NetExpensesOverAssets	0.61%	[2]
1	rr_ExpenseExampleYear01	$ 62
3	rr_ExpenseExampleYear03	221
5	rr_ExpenseExampleYear05	394
10	rr_ExpenseExampleYear10	895
1	rr_ExpenseExampleNoRedemptionYear01	62
3	rr_ExpenseExampleNoRedemptionYear03	221
5	rr_ExpenseExampleNoRedemptionYear05	394
10	rr_ExpenseExampleNoRedemptionYear10	$ 895
1 Year	rr_AverageAnnualReturnYear01	28.23%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
InceptionDate	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2019
Pioneer Fund | R
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.67%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.28%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.45%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Net Expenses	rr_NetExpensesOverAssets	1.45%	[2]
1	rr_ExpenseExampleYear01	$ 148
3	rr_ExpenseExampleYear03	459
5	rr_ExpenseExampleYear05	792
10	rr_ExpenseExampleYear10	1,735
1	rr_ExpenseExampleNoRedemptionYear01	148
3	rr_ExpenseExampleNoRedemptionYear03	459
5	rr_ExpenseExampleNoRedemptionYear05	792
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,735
1 Year	rr_AverageAnnualReturnYear01	27.28%
5 Years	rr_AverageAnnualReturnYear05	19.40%
10 Years	rr_AverageAnnualReturnYear10	15.48%
InceptionDate	rr_AverageAnnualReturnInceptionDate	Apr. 01, 2003
Pioneer Fund | Y
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.67%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.14%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.81%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.20%	[2]
Net Expenses	rr_NetExpensesOverAssets	0.61%	[2]
1	rr_ExpenseExampleYear01	$ 62
3	rr_ExpenseExampleYear03	239
5	rr_ExpenseExampleYear05	430
10	rr_ExpenseExampleYear10	983
1	rr_ExpenseExampleNoRedemptionYear01	62
3	rr_ExpenseExampleNoRedemptionYear03	239
5	rr_ExpenseExampleNoRedemptionYear05	430
10	rr_ExpenseExampleNoRedemptionYear10	$ 983
1 Year	rr_AverageAnnualReturnYear01	28.24%
5 Years	rr_AverageAnnualReturnYear05	20.22%
10 Years	rr_AverageAnnualReturnYear10	16.26%
InceptionDate	rr_AverageAnnualReturnInceptionDate	May 06, 2099
Pioneer Fund | Return After Taxes on Distributions | A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	15.40%
5 Years	rr_AverageAnnualReturnYear05	14.85%
10 Years	rr_AverageAnnualReturnYear10	11.52%
Pioneer Fund | Return After Taxes on Distributions and Sale of Fund Shares | A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	13.94%
5 Years	rr_AverageAnnualReturnYear05	13.80%
10 Years	rr_AverageAnnualReturnYear10	11.29%
Pioneer Fund | Standard & Poor's 500 Index (reflects no deduction for fees, expenses or taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	28.71%
5 Years	rr_AverageAnnualReturnYear05	18.47%
10 Years	rr_AverageAnnualReturnYear10	16.55%

[1] Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See “Sales charges.”

[2] The fund’s investment adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than taxes, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, such as litigation) to the extent required to reduce fund expenses to 0.61% and 0.61% of the average daily net assets attributable to Class K shares and Class Y shares, respectively. These expense limitations are in effect through May 1, 2023. There can be no assurance that the adviser will extend the expense limitations beyond such time. Net expenses for a class may exceed the applicable expense limitation to the extent that the fund incurs excluded expenses.While in effect, the arrangement may be terminated for a class only by agreement of the adviser and the Board of Trustees.