Objective, Primary [Text Block]

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Risk/Return [Heading]

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FRANKLIN S&P 500 INDEX FUND

Objective [Heading]

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Investment objective

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The fund seeks to provide investment results that, before fees and expenses, correspond to the price and yield performance of the S&P 500^® Index (the “Index”).

Expense [Heading]

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Fees and expenses of the fund

Expense Narrative [Text Block]

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The accompanying 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.

Shareholder Fees Caption [Text]

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Shareholder fees(fees paid directly from your investment)

Operating Expenses Caption [Text]

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Annual fund operating expenses (%)(expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

December 31, 2026

Portfolio Turnover [Heading]

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Portfolio turnover.

Portfolio Turnover [Text Block]

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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 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 1% of the average value of its portfolio.

Portfolio Turnover, Rate

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1.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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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:

•

You invest $10,000 in the fund for the time periods indicated

•

Your investment has a 5% return each year and the fund’s operating expenses remain the same (except that any applicable fee waiver or expense reimbursement is reflected only through its expiration date)

•

You reinvest all distributions and dividends without a sales charge

Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example by, Year, Caption [Text]

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Number of years you own your shares ($)

Expense Example, No Redemption, By Year, Caption [Text]

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Number of years you own your shares ($)

Strategy [Heading]

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Principal investment strategies

Strategy Narrative [Text Block]

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Under normal circumstances, the fund invests at least 80% of its net assets, plus borrowings for investment purposes, if any, in equity securities, or other investments with similar economic characteristics, included in the Index. The fund seeks to be fully invested in stocks included in the Index. The fund seeks to hold a portfolio of common stocks that is comparable to the Index in terms of economic sector weightings, market capitalization and liquidity. The Index is a well-known stock market index that includes common stocks of 500 companies from a number of sectors and that measures the performance of large capitalization companies of the U.S. equities market.

By seeking to track the Index, from time to time, the fund may be significantly invested in companies in a particular sector. In recent years, the Index, which is market capitalization-weighted, has become significantly more exposed to companies in the information technology sector relative to other sectors, as a result of the increased market capitalization of companies in this sector.

The fund may also use derivatives to track the performance of the Index. The fund might do so, for example, in order to increase its investment exposure pending investment of cash in the stocks comprising the Index.

Risk [Heading]

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Principal risks

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

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The accompanying bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Class A shares. The table shows the average annual total returns of each class of the fund that has been in operation for at least one full calendar year and also compares the fund’s performance with the average annual total returns of a broad measure of market performance and the S&P 500 Index. Performance for classes other than those shown may vary from the performance shown to the extent the expenses for those classes differ. The fund makes updated performance information, including its current net asset value, available at www.franklintempleton.com/mutualfunds (select fund and share class), or by calling the fund at (877) 6LM‑FUND/656‑3863.

The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart shows changes in the fund’s performance from year to year for Class A shares. The table shows the average annual total returns of each class of the fund that has been in operation for at least one full calendar year and also compares the fund’s performance with the average annual total returns of a broad measure of market performance and the S&P 500 Index.

Performance Availability Phone [Text]

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(877) 6LM‑FUND/656‑3863

Performance Availability Website Address [Text]

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www.franklintempleton.com/mutualfunds (select fund and share class)

Performance Past Does Not Indicate Future [Text]

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The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

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Total returns (%) Before taxes

Bar Chart Closing [Text Block]

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Calendar Years ended December 31 Best Quarter (06/30/2020): 20.37 Worst Quarter (03/31/2020): (19.68)

Performance Table Heading

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Average annual total returns (%)(for periods ended December 31, 2024)

Performance Table Uses Highest Federal Rate

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Performance Table Not Relevant to Tax Deferred

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Actual after‑tax returns depend on an investor’s tax situation and may differ from those shown, and the after‑tax returns shown are not relevant to investors who hold their fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

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The after‑tax returns are shown only for Class A shares, 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 an investor’s tax situation and may differ from those shown, and the after‑tax returns shown are not relevant to investors who hold their fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After‑tax returns for classes other than Class A will vary from returns shown for Class A.

Performance Table Narrative

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Franklin S&P 500 Index Fund | Risk Lose Money [Member]

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Franklin S&P 500 Index Fund | Risk Not Insured Depository Institution [Member]

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You may lose part or all of your investment in the fund or your investment may not perform as well as other similar investments.

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Franklin S&P 500 Index Fund | Index investing risk [Member]

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An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or by any bank or government agency.

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Franklin S&P 500 Index Fund | Market events risk [Member]

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Index investing risk. As an index fund, the fund does not attempt to manage market volatility, use defensive strategies or reduce the effects of any periods of poor stock performance. The fund’s expenses, changes in securities markets, changes in the composition of the Index and the timing of purchases and redemptions of fund shares may affect the correlation between fund and Index performance. The fund may not perform as well as other investments if, among other things, the Index declines or performs poorly relative to other related indexes or individual securities or the securities issued by companies that comprise the Index fall out of favor with investors. Certain regulatory limitations, such as fund diversification requirements, may limit the fund’s ability to completely replicate the Index. The index used by the fund is weighted by market capitalization, which means that poor performance by one or a few stocks with large market capitalizations could adversely affect the fund’s performance relative to other investments.

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Franklin S&P 500 Index Fund | Stock market and equity securities risk [Member]

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Market events risk. The market values of securities or other assets will fluctuate, sometimes sharply and unpredictably, due to factors such as economic events, governmental actions or intervention, actions taken by the U.S. Federal Reserve or foreign central banks, market disruptions caused by trade disputes, labor strikes or other factors, political developments, armed conflicts, economic sanctions and countermeasures in response to sanctions, major cybersecurity events, the global and domestic effects of widespread or local health, weather or climate events, and other factors that may or may not be related to the issuer of the security or other asset. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, public health events, terrorism, wars, natural disasters and other circumstances in one country or region could have profound impacts 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 markets directly affected, the value and liquidity of the fund’s investments may be negatively affected. Ongoing armed conflicts between Russia and Ukraine in Europe and among Israel, Hamas and other militant groups in the Middle East have caused and could continue to cause significant market disruptions and volatility. The hostilities and sanctions resulting from those hostilities have and could continue to have a significant impact on certain fund investments as well as fund performance and liquidity. Following Russia’s invasion of Ukraine in 2022, Russian stocks lost all, or nearly all, of their market value. Other securities or markets could be similarly affected by past or future geopolitical or other events or conditions. Furthermore, events involving limited liquidity, defaults, non‑performance or other adverse developments that affect one industry, such as the financial services industry, or concerns or rumors about any events of these kinds, have in the past and may in the future lead to market-wide liquidity problems, may spread to other industries, and could negatively affect the value and liquidity of the fund’s investments.

Raising the ceiling on U.S. government debt has become increasingly politicized. Any failure to increase the total amount that the U.S. government is authorized to borrow could lead to a default on U.S. government obligations, with unpredictable consequences for economies and markets in the U.S. and elsewhere. Recently, inflation and interest rates have been volatile and may increase in the future. These circumstances could adversely affect the value and liquidity of the fund’s investments, impair the fund’s ability to satisfy redemption requests, and negatively impact the fund’s performance.

The United States and other countries are periodically involved in disputes over trade and other matters, which may result in tariffs, investment restrictions and adverse impacts on affected companies and securities. For example, the United States has imposed tariffs and other trade barriers on Chinese exports, has restricted sales of certain categories of goods to China, and has established barriers to investments in China. Trade disputes may adversely affect the economies of the United States and its trading partners, as well as companies directly or indirectly affected and financial markets generally. The United States government has prohibited U.S. persons from investing in Chinese companies designated as related to the Chinese military. These and possible future restrictions could limit the fund’s opportunities for investment and require the sale of securities at a loss or make them illiquid. Moreover, the Chinese government is involved in a longstanding dispute with Taiwan that has included threats of invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt unification of Taiwan by force, or if other geopolitical conflicts develop or get worse, economies, markets and individual securities may be severely affected both regionally and globally, and the value of the fund’s assets may go down.

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Franklin S&P 500 Index Fund | Issuer risk [Member]

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Stock market and equity securities risk. The stock markets are volatile and the market prices of equity securities held by the fund may go up or down, sometimes rapidly or unpredictably. Equity securities may include exchange-traded and over‑the‑counter common stocks, preferred stock, depositary receipts, trust certificates, limited partnership interests, warrants, rights, securities convertible into equity securities, and shares of other investment companies, including exchange-traded funds, and of real estate investment trusts. Equity securities may have greater price volatility than other asset classes, such as fixed income securities. The market price of a security may fluctuate based on overall market conditions, such as real or perceived adverse economic or political conditions or trends, tariffs and trade disruptions, inflation, substantial

economic downturn or recession, changes in interest rates, or adverse investor sentiment. Changes in market conditions will not typically have the same impact on all types of securities. If the market prices of the equity securities owned by the fund fall, the value of your investment in the fund will decline. If the fund holds equity securities in a company that becomes insolvent, the fund’s interests in the company will be subordinated to the interests of debtholders and general creditors of the company, and the fund may lose its entire investment.

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Franklin S&P 500 Index Fund | Industry or sector focus risk [Member]

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Issuer risk. The market price of a security held by the fund can go up or down more than the market as a whole and can perform differently from the value of the market as a whole due to factors specifically relating to the security’s issuer, such as disappointing earnings reports by the issuer, unsuccessful products or services, loss of major customers, changes in management, corporate actions, negative perception in the marketplace, or major litigation or changes in government regulations affecting the issuer or the competitive environment. An individual security may also be affected by factors relating to the industry or sector of the issuer or the securities markets as a whole, and conversely an industry or sector or the securities markets may be affected by a change in financial condition or other event affecting a single issuer. The fund may experience a substantial or complete loss on an individual security.

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Franklin S&P 500 Index Fund | Information technology sector risks [Member]

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Industry or sector focus risk. The fund may be susceptible to an increased risk of loss, including losses due to events that adversely affect the fund’s investments more than the market as a whole, to the extent that the fund may, from time to time, have greater exposure to the securities of a particular issuer or issuers within the same industry or sector.

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Franklin S&P 500 Index Fund | Derivatives risks [Member]

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Information technology sector risk. Companies in the rapidly changing field of information technology face special risks. Additionally, companies in this field are dependent upon consumer and business acceptance as new technologies evolve. Information technology companies face intense competition and potentially rapid product obsolescence. They are also heavily dependent on intellectual property rights and may be adversely affected by the loss or impairment of, or inability to enforce, those rights.

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Franklin S&P 500 Index Fund | Illiquidity risk [Member]

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Derivatives risk. Using derivatives can increase fund losses and reduce opportunities for gains, such as when market prices, interest rates, currencies, or the derivatives themselves, behave in a way not anticipated by the fund’s subadviser. Using derivatives also can have a leveraging effect and increase fund volatility. Certain derivatives have the potential for unlimited loss, regardless of the size of the initial investment. Derivatives may not be available at the time or price desired, may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. Derivatives are generally subject to the risks applicable to the assets, rates, indices or other indicators underlying the derivative. The value of a derivative may fluctuate more than the underlying assets, rates, indices or other indicators to which it relates. Use of derivatives may have different tax consequences for the fund than an investment in the underlying asset, and those differences may affect the

amount, timing and character of income distributed to shareholders. The U.S. government and non‑U.S. governments have adopted and implemented 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 derivatives more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets.

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Franklin S&P 500 Index Fund | Valuation risk [Member]

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Illiquidity risk. Some assets held by the fund may be or become impossible or difficult to sell, particularly during times of market turmoil. These illiquid assets may also be difficult to value. Markets may become illiquid quickly. Markets may become illiquid when, for instance, there are few, if any, interested buyers or sellers or when dealers are unwilling or unable to make a market for certain securities. As a general matter, dealers have been less willing to make markets in recent years. If the fund is forced to sell an illiquid asset to meet redemption requests or other cash needs, or to try to limit losses, the fund may be forced to sell at a substantial loss or may not be able to sell at all.

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Franklin S&P 500 Index Fund | Cybersecurity risk [Member]

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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 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 securities or had used a different valuation methodology. The fund’s ability to value its investments may be impacted by technological issues and/or errors by pricing services or other third party service providers. The valuation of the fund’s investments involves subjective judgment, which may prove to be incorrect.

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Franklin S&P 500 Index Fund | Class A

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Cybersecurity risk. Like other funds and business enterprises, the fund, the manager, the subadvisers and their service providers are subject to the risk of cyber incidents occurring from time to time. Cybersecurity incidents, whether intentionally caused by third parties or otherwise, may allow an unauthorized party to gain access to fund assets, fund or customer data (including private shareholder information) or proprietary information, cause the fund, the manager, the subadvisers and/or their service providers (including, but not limited to, fund accountants, custodians, sub‑custodians, transfer agents and financial intermediaries) to suffer data breaches, data corruption or loss of operational functionality, or prevent fund investors from purchasing, redeeming or exchanging shares, receiving distributions or receiving timely information regarding the fund or their investment in the fund. The fund, the manager, and the subadvisers have limited ability to prevent or mitigate cybersecurity incidents affecting third party service providers, and such third party service providers may have limited indemnification obligations to the fund, the manager, and/or the subadvisers. Cybersecurity incidents may result in financial losses to the fund and its shareholders, and substantial costs may be incurred in order to prevent or mitigate any future cybersecurity incidents. Issuers of securities in which the fund invests are also subject to cybersecurity risks, and the value of these securities could decline if the issuers experience cybersecurity incidents.

New ways to carry out cyber attacks continue to develop. There is a chance that some risks have not been identified or prepared for, or that an attack may not be detected, which puts limitations on the fund’s ability to plan for or respond to a cyber attack.

Maximum sales charge (load) imposed on purchases (as a % of offering price)

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none

Maximum deferred sales charge (load) (as a % of the lower of net asset value at purchase or redemption)

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none

Small account fee ($)

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$ 15

^[1]

Management fees

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0.25%

Distribution and/or service (12b-1) fees

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0.20%

Other expenses

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0.13%

Total annual fund operating expenses

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0.58%

Fees waived and/or expenses reimbursed

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(0.04%)

^[2]

Total annual fund operating expenses after waiving fees and/or reimbursing expenses

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0.54%

rr_ExpenseExampleYear01

$ 55

rr_ExpenseExampleYear03

182

rr_ExpenseExampleYear05

321

rr_ExpenseExampleYear10

724

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rr_ExpenseExampleNoRedemptionYear03

182

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321

Highest Quarterly Return, Label

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$ 724

2015

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0.82%

2016

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11.37%

2017

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21.14%

2018

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(4.93%)

2019

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30.67%

2020

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17.81%

2021

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27.96%

2022

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(18.41%)

2023

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25.62%

2024

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24.36%

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Best Quarter

Highest Quarterly Return, Date

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Jun. 30, 2020

Highest Quarterly Return

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20.37%

Lowest Quarterly Return, Label

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Worst Quarter

Lowest Quarterly Return, Date

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Mar. 31, 2020

Lowest Quarterly Return

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(19.68%)

rr_AverageAnnualReturnYear01

24.36%

rr_AverageAnnualReturnYear05

13.95%

Franklin S&P 500 Index Fund | Class D

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12.50%

Maximum sales charge (load) imposed on purchases (as a % of offering price)

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none

Maximum deferred sales charge (load) (as a % of the lower of net asset value at purchase or redemption)

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none

Small account fee ($)

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none

^[1]

Management fees

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0.25%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

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0.14%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.39%

Fees waived and/or expenses reimbursed

rr_FeeWaiverOrReimbursementOverAssets

(0.05%)

^[2]

Total annual fund operating expenses after waiving fees and/or reimbursing expenses

rr_NetExpensesOverAssets

0.34%

rr_ExpenseExampleYear01

$ 35

rr_ExpenseExampleYear03

121

rr_ExpenseExampleYear05

215

rr_ExpenseExampleYear10

489

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rr_ExpenseExampleNoRedemptionYear03

121

rr_ExpenseExampleNoRedemptionYear05

215

rr_ExpenseExampleNoRedemptionYear10

$ 489

rr_AverageAnnualReturnYear01

24.59%

rr_AverageAnnualReturnYear05

14.18%

Franklin S&P 500 Index Fund | Return after taxes on distributions | Class A

rr_AverageAnnualReturnYear10

12.72%

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rr_AverageAnnualReturnYear01

24.04%

rr_AverageAnnualReturnYear05

13.04%

Franklin S&P 500 Index Fund | Return after taxes on distributions and sale of fund shares | Class A

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11.46%

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rr_AverageAnnualReturnYear01

14.66%

rr_AverageAnnualReturnYear05

10.99%

Franklin S&P 500 Index Fund | Russell 3000 Index (reflects no deduction for fees, expenses or taxes)

rr_AverageAnnualReturnYear10

10.07%

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rr_AverageAnnualReturnYear01

23.81%

rr_AverageAnnualReturnYear05

13.86%

Franklin S&P 500 Index Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

rr_AverageAnnualReturnYear10

12.55%

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rr_AverageAnnualReturnYear01

25.02%

rr_AverageAnnualReturnYear05

14.53%