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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName FRANKLIN CUSTODIAN FUNDS
Prospectus Date rr_ProspectusDate Feb. 01, 2015
Risk/Return [Heading] rr_RiskReturnHeading Fund Summary
Franklin Custodian Funds-14 | Franklin Growth Fund  
Risk/Return: rr_RiskReturnAbstract  
Objective [Heading] rr_ObjectiveHeading Investment Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock Capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock 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 $50,000 in Franklin Templeton funds. More information about these and other discounts is available from your financial professional and under “Your Account” on page 107 in the Fund's Prospectus and under “Buying and Selling Shares” on page 70 of the Fund’s Statement of Additional Information.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption

Annual Fund Operating Expenses

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

Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The Fund pays transaction 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 1.50% of the average value of its portfolio.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 1.50%rr_PortfolioTurnoverRate
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Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts 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 $50,000 in Franklin Templeton funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount 50,000rr_ExpenseBreakpointMinimumInvestmentRequiredAmount
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Expense Example [Heading] rr_ExpenseExampleHeading Example
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 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. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If you do not sell your shares:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund invests substantially in the equity securities of companies that are leaders in their industries. In selecting securities, the investment manager considers many factors, including historical and potential growth in revenues and earnings, assessment of strength and quality of management, and determination of a company's strategic positioning in its industry.

Although the Fund normally invests substantially in the equity securities (principally common stocks) of U.S.-based large and medium market capitalization companies, it may invest in companies in new and emerging industries where growth is expected to be above average and may invest up to 40% of its assets in smaller companies.

The Fund's investment manager is a research driven, fundamental investor, generally pursuing a "buy-and-hold" growth strategy. As a "bottom-up" investor focusing primarily on individual securities, the investment manager chooses companies that it believes are positioned for growth in revenues, earnings or assets. Such advantages as a particular marketing niche, proven technology, sound financial records, strong management, and industry leadership are all factors the investment manager believes point to strong growth potential. Although the investment manager searches for investments across a large number of sectors, from time to time, based on economic conditions, the Fund may have significant positions in particular sectors.

Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration Under normal market conditions, the Fund invests substantially in the equity securities of companies that are leaders in their industries.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

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.

Market

The market values of securities or other investments owned by the Fund will go up or down, sometimes rapidly or unpredictably. A security’s market value 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 securities. When there are more sellers than buyers, prices tend to fall. Likewise, when there are more buyers than sellers, prices tend to rise.

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.

Focus

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.

Midsize Companies

Securities issued by midsize companies may be more volatile in price than those of larger companies, involve substantial risks and should be considered speculative. Such risks may include greater sensitivity to economic conditions, less certain growth prospects, lack of depth of management and funds for growth and development and limited or less developed product lines and markets.

Growth Style Investing

Growth stock prices reflect projections of future earnings or revenues, and can, therefore, fall dramatically if the company fails to meet those projections. Prices of these companies’ securities may be more volatile than other securities, particularly over the short term.

Management

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.

Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

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.

Sales charges are not reflected in the bar chart, and if those charges were included, returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns 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.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone (800) DIAL BEN/342-5236
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress franklintempleton.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture 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] rr_BarChartHeading Class A Annual Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges are not reflected in the bar chart, and if those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best Quarter:Q3'0917.60%
Worst Quarter:Q4'08-20.30%
Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns
(figures reflect sales charges)

For the periods ended December 31, 2014

Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock

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.

Franklin Custodian Funds-14 | Franklin Growth Fund | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price) rr_MaximumCumulativeSalesChargeOverOfferingPrice 5.75%rr_MaximumCumulativeSalesChargeOverOfferingPrice
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Maximum Deferred Sales Charge (Load) (as percentage of the lower of original purchase price or sale proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management fees rr_ManagementFeesOverAssets 0.45%rr_ManagementFeesOverAssets
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Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%rr_DistributionAndService12b1FeesOverAssets
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Other expenses rr_OtherExpensesOverAssets 0.20%rr_OtherExpensesOverAssets
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Total annual Fund operating expenses rr_ExpensesOverAssets 0.90%rr_ExpensesOverAssets
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2005 rr_AnnualReturn2005 8.36%rr_AnnualReturn2005
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2006 rr_AnnualReturn2006 14.16%rr_AnnualReturn2006
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2007 rr_AnnualReturn2007 7.13%rr_AnnualReturn2007
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2008 rr_AnnualReturn2008 (33.39%)rr_AnnualReturn2008
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2009 rr_AnnualReturn2009 34.25%rr_AnnualReturn2009
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2010 rr_AnnualReturn2010 14.87%rr_AnnualReturn2010
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2011 rr_AnnualReturn2011 0.63%rr_AnnualReturn2011
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2012 rr_AnnualReturn2012 13.69%rr_AnnualReturn2012
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Annual Return 2013 rr_AnnualReturn2013 29.39%rr_AnnualReturn2013
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Annual Return 2014 rr_AnnualReturn2014 14.88%rr_AnnualReturn2014
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Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.60%rr_BarChartHighestQuarterlyReturn
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Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.30%)rr_BarChartLowestQuarterlyReturn
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Franklin Custodian Funds-14 | Franklin Growth Fund | Class C  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price) rr_MaximumCumulativeSalesChargeOverOfferingPrice none
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[1]
Management fees rr_ManagementFeesOverAssets 0.45%rr_ManagementFeesOverAssets
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Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%rr_DistributionAndService12b1FeesOverAssets
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Other expenses rr_OtherExpensesOverAssets 0.20%rr_OtherExpensesOverAssets
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Total annual Fund operating expenses rr_ExpensesOverAssets 1.65%rr_ExpensesOverAssets
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Franklin Custodian Funds-14 | Franklin Growth Fund | Class R  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price) rr_MaximumCumulativeSalesChargeOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as percentage of the lower of original purchase price or sale proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management fees rr_ManagementFeesOverAssets 0.45%rr_ManagementFeesOverAssets
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Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.50%rr_DistributionAndService12b1FeesOverAssets
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Total annual Fund operating expenses rr_ExpensesOverAssets 1.15%rr_ExpensesOverAssets
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Franklin Custodian Funds-14 | Franklin Growth Fund | Class R6  
Risk/Return: rr_RiskReturnAbstract  
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Maximum Deferred Sales Charge (Load) (as percentage of the lower of original purchase price or sale proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
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Franklin Custodian Funds-14 | Franklin Growth Fund | Advisor Class  
Risk/Return: rr_RiskReturnAbstract  
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Maximum Deferred Sales Charge (Load) (as percentage of the lower of original purchase price or sale proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management fees rr_ManagementFeesOverAssets 0.45%rr_ManagementFeesOverAssets
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Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.20%rr_OtherExpensesOverAssets
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10 years rr_ExpenseExampleYear10 809rr_ExpenseExampleYear10
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_ProspectusShareClassAxis
= fcf_C000018327Member
Franklin Custodian Funds-14 | Franklin Growth Fund | Return Before Taxes | Class A  
Risk/Return: rr_RiskReturnAbstract  
Column rr_AverageAnnualReturnColumnName Franklin Growth Fund
Label rr_AverageAnnualReturnLabel Return Before Taxes
Past 1 year rr_AverageAnnualReturnYear01 8.27%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Past 5 years rr_AverageAnnualReturnYear05 12.98%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Past 10 years rr_AverageAnnualReturnYear10 8.11%rr_AverageAnnualReturnYear10
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Franklin Custodian Funds-14 | Franklin Growth Fund | Return Before Taxes | Class C  
Risk/Return: rr_RiskReturnAbstract  
Past 1 year rr_AverageAnnualReturnYear01 13.01%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018326Member
Past 5 years rr_AverageAnnualReturnYear05 13.48%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018326Member
Past 10 years rr_AverageAnnualReturnYear10 7.94%rr_AverageAnnualReturnYear10
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018326Member
Franklin Custodian Funds-14 | Franklin Growth Fund | Return Before Taxes | Class R  
Risk/Return: rr_RiskReturnAbstract  
Past 1 year rr_AverageAnnualReturnYear01 14.58%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018328Member
Past 5 years rr_AverageAnnualReturnYear05 14.04%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018328Member
Past 10 years rr_AverageAnnualReturnYear10 8.48%rr_AverageAnnualReturnYear10
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018328Member
Franklin Custodian Funds-14 | Franklin Growth Fund | Return Before Taxes | Class R6  
Risk/Return: rr_RiskReturnAbstract  
Past 1 year rr_AverageAnnualReturnYear01 15.36%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000128786Member
Past 5 years rr_AverageAnnualReturnYear05 21.86%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000128786Member
[2]
Franklin Custodian Funds-14 | Franklin Growth Fund | Return Before Taxes | Advisor Class  
Risk/Return: rr_RiskReturnAbstract  
Past 1 year rr_AverageAnnualReturnYear01 15.15%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018327Member
Past 5 years rr_AverageAnnualReturnYear05 14.62%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018327Member
Past 10 years rr_AverageAnnualReturnYear10 9.03%rr_AverageAnnualReturnYear10
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_ReturnBeforeTaxesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018327Member
Franklin Custodian Funds-14 | Franklin Growth Fund | Return After Taxes on Distributions | Class A  
Risk/Return: rr_RiskReturnAbstract  
Column rr_AverageAnnualReturnColumnName Franklin Growth Fund
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
Past 1 year rr_AverageAnnualReturnYear01 8.20%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= rr_AfterTaxesOnDistributionsMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Past 5 years rr_AverageAnnualReturnYear05 12.90%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= rr_AfterTaxesOnDistributionsMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Past 10 years rr_AverageAnnualReturnYear10 8.03%rr_AverageAnnualReturnYear10
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= rr_AfterTaxesOnDistributionsMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Franklin Custodian Funds-14 | Franklin Growth Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class A  
Risk/Return: rr_RiskReturnAbstract  
Column rr_AverageAnnualReturnColumnName Franklin Growth Fund
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
Past 1 year rr_AverageAnnualReturnYear01 4.73%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= rr_AfterTaxesOnDistributionsAndSalesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Past 5 years rr_AverageAnnualReturnYear05 10.41%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= rr_AfterTaxesOnDistributionsAndSalesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Past 10 years rr_AverageAnnualReturnYear10 6.62%rr_AverageAnnualReturnYear10
/ dei_DocumentInformationDocumentAxis
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= rr_AfterTaxesOnDistributionsAndSalesMember
/ rr_ProspectusShareClassAxis
= fcf_C000018324Member
Franklin Custodian Funds-14 | Franklin Growth Fund | S&P 500® Index (index reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
Past 1 year rr_AverageAnnualReturnYear01 13.69%rr_AverageAnnualReturnYear01
/ dei_DocumentInformationDocumentAxis
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/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_IndexHB0331Member
Past 5 years rr_AverageAnnualReturnYear05 15.46%rr_AverageAnnualReturnYear05
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
= fcf_IndexHB0331Member
Past 10 years rr_AverageAnnualReturnYear10 7.68%rr_AverageAnnualReturnYear10
/ dei_DocumentInformationDocumentAxis
= fcf_FranklinCustodianFunds14Member
/ dei_LegalEntityAxis
= fcf_S000006755Member
/ rr_PerformanceMeasureAxis
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[1] There is a 1% contingent deferred sales charge that applies to investments of $1 million or more (see "Investments of $1 Million or More" under "Choosing a Share Class") and purchases by certain retirement plans without an initial sales charge.
[2] Since inception May 01, 2013.