00000387212019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:C000199719Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:C000018329Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:C000018332Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:C000018334Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:C000128787Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:C000018333Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:ReturnBeforeTaxesMemberfcf:C000199719Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberrr:AfterTaxesOnDistributionsMemberfcf:C000199719Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberrr:AfterTaxesOnDistributionsAndSalesMemberfcf:C000199719Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:ReturnBeforeTaxesMemberfcf:C000018329Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:ReturnBeforeTaxesMemberfcf:C000018332Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:ReturnBeforeTaxesMemberfcf:C000018334Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:ReturnBeforeTaxesMemberfcf:C000128787Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:ReturnBeforeTaxesMemberfcf:C000018333Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:IndexHB0331Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:IndexHB10288Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:IndexBM0838Member2019-03-292019-03-290000038721fcf:S000006756Memberfcf:FranklinCustodianFunds26Memberfcf:IndexLM8920Member2019-03-292019-03-29 iso4217:USD xbrli:pure xbrli:shares iso4217:USD xbrli:shares 0000038721FRANKLIN CUSTODIAN FUNDS4972019-03-282019-03-292018-09-30falseN-1A2019-03-29Fund SummaryInvestment GoalTo maximize income while maintaining prospects for capital appreciation.Fees and Expenses of the FundYou may qualify for sales charge discounts in Class A if you and your family invest, or agree to invest in the future, at least $100,000 in Franklin Templeton funds.100000<div><p>These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts in Class A if you and your family invest, or agree to invest in the future, at least $100,000 in Franklin Templeton funds. More information about these and other discounts is available from your financial professional and under &#147;Your Account&#148; on page 118 in the Fund's Prospectus and under &#147;Buying and Selling Shares&#148; on page 82 of the Fund&#146;s Statement of Additional Information. In addition, more information about sales charge discounts and waivers for purchases of shares through specific financial intermediaries is set forth in Appendix A &#150; "Intermediary Sales Charge Discounts and Waivers" to the Fund&#146;s prospectus.</p><p>Please note that the tables and examples below do not reflect any transaction fees that may be charged by financial intermediaries, or commissions that a shareholder may be required to pay directly to its financial intermediary when buying or selling Class R6 or Advisor Class shares.</p></div>Shareholder Fees (fees paid directly from your investment)~ http://www.proofPlus.com/role/ShareholderFeesS000006756_FranklinCustodianFunds26 column period compact * ~0.03750.03750.000.000.000.000.000.000.01000.000.000.00<div><p>Annual Fund Operating Expenses</p><p>(expenses that you pay each year as a percentage of the value of your investment)</p></div>~ http://www.proofPlus.com/role/OperatingExpensesS000006756_FranklinCustodianFunds26 column period compact * ~0.00370.00370.00370.00370.00370.00370.00250.00150.00650.00500.000.000.00090.00090.00090.00090.00020.00090.00010.00010.00010.00010.00010.00010.00720.00620.01120.00970.00400.0047ExampleThis 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 indicated and then redeem all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The Example reflects adjustments made to the Fund's operating expenses due to the fee waivers and/or expense reimbursements by management for the 1 Year numbers only. Although your actual costs may be higher or lower, based on these assumptions your costs would be:4956458091281~ http://www.proofPlus.com/role/ExpenseExampleS000006756_FranklinCustodianFunds26 column period compact * ~486615756116621435661713639930953611904112822450548151263591If you do not sell your shares:~ http://www.proofPlus.com/role/ExpenseExampleNoRedemptionS000006756_FranklinCustodianFunds26 column period compact * ~1143566171363Portfolio Turnover0.4995<div><p>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 49.95% of the average value of its portfolio.</p></div>Principal Investment Strategies<div><p>Under normal market conditions, the Fund invests in a diversified portfolio of debt and equity securities. The Fund may shift its investments from one asset class to another based on the investment manager's analysis of the best opportunities for the Fund&#146;s portfolio in a given market. The equity securities in which the Fund invests consist primarily of common stocks. Debt securities include all varieties of fixed, floating and variable rate instruments, including secured and unsecured bonds, bonds convertible into common stock, senior floating rate and term loans, mortgage-backed securities and other asset-backed securities, debentures, and shorter term instruments. The Fund seeks income by selecting investments such as corporate, foreign and U.S. Treasury bonds, as well as stocks with dividend yields the investment manager believes are attractive. The Fund may invest up to 100% of its total assets in debt securities that are rated below investment grade (also known as "junk bonds"), including a portion in defaulted securities. The Fund maintains the flexibility to invest in securities of companies from a variety of sectors, but from time to time, based on economic conditions, the Fund may have significant investments in particular sectors. The Fund may also invest up to 25% of its assets in foreign securities, either directly or through depositary receipts.</p><p>The Fund may, from time to time, use a variety of equity-related derivatives and complex equity securities, which may include purchasing or selling call and put options on equity securities and equity security indices, futures on equity securities and equity indexes, options on equity index futures and equity-linked notes, for various purposes including enhancing Fund returns, increasing liquidity, gaining exposure to particular instruments in more efficient or less expensive ways and/or hedging risks relating to changes in certain equity markets. In addition, the Fund may use interest rate derivatives, including interest rate swaps and interest rate and/or bond futures contracts (including U.S. Treasury futures contracts) for various purposes including enhancing Fund returns, increasing liquidity, gaining exposure to particular instruments in more efficient or less expensive ways and/or hedging risks relating to changes in interest rates. The Fund also may, from time to time, use currency derivatives, such as forward foreign currency exchange contracts, currency futures contracts, currency swaps and currency options to hedge (protect) against currency risks, and credit-related derivatives, such as credit default swaps and options on credit default swaps, to hedge (protect) against credit risks. The use of such derivative transactions may allow the Fund to obtain net long or net short exposures to selected markets, interest rates, countries or durations.</p><p>The Fund's investment manager searches for undervalued or out-of-favor securities it believes offer opportunities for income today and significant growth tomorrow. It generally performs independent analysis of the debt securities being considered for the Fund's portfolio, rather than relying principally on the ratings assigned by rating organizations. In analyzing both debt and equity securities, the investment manager considers a variety of factors, including:</p><p>a security's relative value based on such factors as anticipated cash flow, interest or dividend coverage, asset coverage, and earnings prospects;</p><p>the experience and strength of the company's management;</p><p>the company's changing financial condition and market recognition of the change;</p><p>the company's sensitivity to changes in interest rates and business conditions; and</p><p>the company's debt maturity schedules and borrowing requirements.</p><p>When choosing equity investments for the Fund, the investment manager applies a "bottom-up," value oriented, long-term approach, focusing on the market price of a company's securities relative to the investment manager's evaluation of the company's long-term earnings, asset value and cash flow potential. The investment manager also considers a company's price/earnings ratio, profit margins and liquidation value.</p></div>Principal Risks<div><p>You could lose money by investing in the Fund. Mutual fund shares are not deposits or obligations of, or guaranteed or endorsed by, any bank, and are not insured by the Federal Deposit Insurance Corporation, the Federal Reserve Board, or any other agency of the U.S. government.</p><p>Market</p><p>The market values of securities or other investments owned by the Fund will go up or down, sometimes rapidly or unpredictably. The market value of a security or other investment may be reduced by market activity or other results of supply and demand unrelated to the issuer. This is a basic risk associated with all investments. When there are more sellers than buyers, prices tend to fall. Likewise, when there are more buyers than sellers, prices tend to rise.</p><p>Stock prices tend to go up and down more dramatically than those of debt securities. A slower-growth or recessionary economic environment could have an adverse effect on the prices of the various stocks held by the Fund.</p><p>High-Yield Debt Securities</p><p>Issuers of lower-rated or &#147;high-yield&#148; debt securities (also known as &#147;junk bonds&#148;) are not as strong financially as those issuing higher credit quality debt securities. High-yield debt securities are generally considered predominantly speculative by the applicable rating agencies as their issuers are more likely to encounter financial difficulties because they may be more highly leveraged, or because of other considerations. In addition, high yield debt securities generally are more vulnerable to changes in the relevant economy, such as a recession or a sustained period of rising interest rates, that could affect their ability to make interest and principal payments when due. The prices of high-yield debt securities generally fluctuate more than those of higher credit quality. High-yield debt securities are generally more illiquid (harder to sell) and harder to value.</p><p>Interest Rate</p><p>When interest rates rise, debt security prices generally fall. The opposite is also generally true: debt security prices rise when interest rates fall. Interest rate changes are influenced by a number of factors, including government policy, monetary policy, inflation expectations, perceptions of risk, and supply of and demand for bonds. In general, securities with longer maturities or durations are more sensitive to interest rate changes.</p><p>Credit</p><p>An issuer of debt securities may fail to make interest payments or repay principal when due, in whole or in part. Changes in an issuer's financial strength or in a security's credit rating may affect a security's value.</p><p>Foreign Securities (non-U.S.)</p><p>Investing in foreign securities typically involves more risks than investing in U.S. securities, including risks related to currency exchange rates and policies, country or government specific issues, less favorable trading practices or regulation and greater price volatility. Certain of these risks also may apply to securities of U.S. companies with significant foreign operations.</p><p>Income</p><p>The Fund's distributions to shareholders may decline when prevailing interest rates fall, when the Fund experiences defaults on debt securities it holds, or when the Fund realizes a loss upon the sale of a debt security.</p><p>Focus</p><p>To the extent that the Fund focuses on particular countries, regions, industries, sectors or types of investment from time to time, the Fund may be subject to greater risks of adverse developments in such areas of focus than a fund that invests in a wider variety of countries, regions, industries, sectors or investments.</p><p>Equity-Linked Notes (ELNs)</p><p>ELNs may not perform as expected and could cause the Fund to realize significant losses including its entire principal investment. Other risks include counterparty risk, liquidity risk and imperfect correlation between ELNs and the underlying securities.</p><p>Management</p><p>The Fund is subject to management risk because it is an actively managed investment portfolio. The Fund's investment manager applies investment techniques and risk analyses in making investment decisions for the Fund, but there can be no guarantee that these decisions will produce the desired results.</p><p>Value Style Investing</p><p>A value stock may not increase in price as anticipated by the investment manager if other investors fail to recognize the company's value and bid up the price, the markets favor faster-growing companies, or the factors that the investment manager believes will increase the price of the security do not occur or do not have the anticipated effect.</p><p>Prepayment</p><p>Prepayment risk occurs when a debt security can be repaid in whole or in part prior to the security's maturity and the Fund must reinvest the proceeds it receives, during periods of declining interest rates, in securities that pay a lower rate of interest. Also, if a security has been purchased at a premium, the value of the premium would be lost in the event of prepayment. Prepayments generally increase when interest rates fall.</p><p>Derivative Instruments</p><p>The performance of derivative instruments depends largely on the performance of an underlying instrument, such as a currency, security, interest rate or index, and such instruments often have risks similar to the underlying instrument, in addition to other risks. Derivatives involve costs and can create economic leverage in the Fund&#146;s portfolio which may result in significant volatility and cause the Fund to participate in losses (as well as gains) in an amount that exceeds the Fund&#146;s initial investment. Other risks include illiquidity, mispricing or improper valuation of the derivative instrument, and imperfect correlation between the value of the derivative and the underlying instrument so that the Fund may not realize the intended benefits. When a derivative is used for hedging, the change in value of the derivative may also not correlate specifically with the currency, security, interest rate, index or other risk being hedged. Derivatives also may present the risk that the other party to the transaction will fail to perform.</p></div>Performancefranklintempleton.com(800) DIAL BEN/342-5236The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.The following 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 how the Fund's average annual returns for 1 year, 5 years, 10 years or since inception, as applicable, compared with those of a broad measure of market performance.Sales charges are not reflected in the bar chart, and if those charges were included, returns would be less than those shown.<div><p>The following 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 how the Fund's average annual returns for 1 year, 5 years, 10 years or since inception, as applicable, compared with those of a broad measure of market performance. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. You can obtain updated performance information at franklintempleton.com or by calling (800) DIAL BEN/342-5236.</p><p>The secondary indices in the table below show how the Fund's performance compares to a group of securities that align with a portion of the Fund's portfolio and to the returns of an index of funds with similar investment objectives as the Fund, respectively.</p><p>Sales charges are not reflected in the bar chart, and if those charges were included, returns would be less than those shown.</p></div>Class A Annual Total Returns0.34990.12900.02820.13670.14220.0411-0.07820.16280.0841-0.0577~ http://www.proofPlus.com/role/AnnualTotalReturnsBarChartS000006756_FranklinCustodianFunds26 column period compact * ~Best Quarter:2009-06-300.1879Worst Quarter:2011-09-30-0.1019<table style="font: 11px sans-serif; background-color:#DDDDDD" border="0" cellspacing="0" cellpadding="5" width="745"><tr><td style="border-bottom: 2px solid #ffffff;" valign="top">Best Quarter:</td><td style="border-bottom: 2px solid #ffffff;" valign="bottom" align="right">Q2'09</td><td style="border-bottom: 2px solid #ffffff;" valign="bottom" align="right">18.79%</td></tr><tr><td style="border-bottom: 2px solid #ffffff;" valign="top">Worst Quarter:</td><td style="border-bottom: 2px solid #ffffff;" valign="bottom" align="right">Q3'11</td><td style="border-bottom: 2px solid #ffffff;" valign="bottom" align="right">-10.19%</td></tr></table><div><p>Average Annual Total Returns<br/>(figures reflect sales charges)</p><p>For the periods ended December 31, 2018</p></div>~ http://www.proofPlus.com/role/AverageAnnualTotalReturnsS000006756_FranklinCustodianFunds26 column period compact * ~Return Before TaxesFranklin Income Fund-0.09770.01770.0830Return After Taxes on DistributionsFranklin Income Fund-0.1161-0.00140.0614Return After Taxes on Distributions and Sale of Fund SharesFranklin Income Fund-0.05680.00670.0585-0.09480.01850.0839-0.06630.02210.0831-0.05740.02350.0848-0.05170.02900.0377-0.05220.02840.0900-0.04380.08500.1312-0.01610.06250.10510.00010.02520.0348-0.05810.03180.0751<div><p>No one index is representative of the Fund's portfolio.</p><p>Historical performance for Class A shares in the bar chart and table above is based on the performance of Class A1 shares and has been adjusted to reflect differences in Rule 12b-1 fees between classes.</p><p>The figures in the average annual total returns table above reflect the Class A and Class A1 maximum front-end sales charge of 4.25% that was in effect prior to March 1, 2019. Class A and A1 shares, however, currently are subject to a maximum front-end sales charge of 3.75% effective on March 1, 2019. If the maximum front-end sales charge of 3.75% was reflected, performance for Class A and Class A1 in the average annual total returns table would be higher.</p><p>The 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 an investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown only for Class A and after-tax returns for other classes will vary.</p></div>Effective October 5, 2018, Class C shares of the Fund convert automatically to Class A shares of the Fund on a monthly basis in the month of, or the month following, the 10-year anniversary of the Class C shares’ purchase date. Such conversions are on the basis of the relative net asset values of the two classes, are not subject to Class A shares’ sales charges and are not expected to be a taxable event for federal income tax purposes. Certain shares that are invested through retirement plans, omnibus accounts or in certain other instances may not automatically convert if the financial intermediary does not have the ability to track purchases to credit individual shareholders’ holding periods. (See “Your Account – Choosing a Share Class – Sales Charges - Class C – Automatic Conversion of Class C Shares to Class A Shares After 10-Year Holding Period” for more information.)The Fund publicly began offering Class A shares (formerly Class M shares) on September 10, 2018.The Example numbers for Class A and A1 shares reflect the maximum sales charge (load) imposed on purchases of Class A and A1 shares of 4.25%, which is the maximum sales charge (load) on purchases of Class A and A1 shares prior to March 1, 2019. If the maximum sales charge (load) on purchases of Class A and A1 shares of 3.75% that was effective on March 1, 2019 was reflected, the expenses for Class A and A1 shares in the chart above would be lower.Total annual Fund operating expenses differ from the ratio of expenses to average net assets shown in the Financial Highlights, which reflect the operating expenses of the Fund and do not include acquired fund fees and expenses.The Blended 50% MSCI USD High Dividend Yield Index + 25% Bloomberg Barclays High Yield Very Liquid Index + 25% Bloomberg Barclays US Aggregate Index is replacing the Bloomberg Barclays U.S. Aggregate Index as a secondary index.The transfer agent has contractually agreed to cap transfer agency fees for Class R6 shares of the Fund so that transfer agency fees for that class do not exceed 0.02% until January 31, 2020. Contractual fee waiver and/or expense reimbursement agreements may not be changed or terminated during the time period set forth above.There is a 0.75% contingent deferred sales charge that applies to investments of $500,000 or more (see "Investments of $500,000 or More – Income, U.S. Government Securities and Utilities Funds" under "Choosing a Share Class") and purchases by certain retirement plans without an initial sales charge on shares sold within 18 months of purchase.The Fund publicly began offering Class A shares on September 10, 2018. Other expenses for Class A are based on estimated amounts for the current fiscal year.Since inception May 1, 2013.Effective March 1, 2019, the maximum sales charge (load) imposed on purchases of Class A and A1 shares is 3.75%. Prior to March 1, 2019, the maximum sales charge (load) on purchases of Class A and A1 shares is 4.25%.