00008097072012-10-012012-10-010000809707fist:S000006855Member2012-10-012012-10-010000809707fist:S000006855Memberfist:C000018523Member2012-10-012012-10-010000809707fist:S000006855Memberfist:C000120960Member2012-10-012012-10-010000809707fist:S000006855Memberfist:C000064444Member2012-10-012012-10-010000809707fist:S000006855Memberfist:C000018523Memberrr:AfterTaxesOnDistributionsMember2012-10-012012-10-010000809707fist:S000006855Memberfist:C000018523Memberrr:AfterTaxesOnDistributionsAndSalesMember2012-10-012012-10-010000809707fist:S000006855Memberfist:Index8935Member2012-10-012012-10-01 iso4217:USD xbrli:pure xbrli:shares iso4217:USD xbrli:shares 0000809707FRANKLIN INVESTORS SECURITIES TRUST485BPOS2012-09-272012-10-012011-10-31false2012-10-01~ http://xbrl.sec.gov/rr/role/RiskReturnDetail column period compact * row primary compact * ~Fund SummaryInvestment GoalA high level of current income as is consistent with prudent investing, while seeking preservation of capital.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.100000These 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 “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 (fees paid directly from your investment)~ http://xbrl.sec.gov/rr/role/ShareholderFeesData column dei_LegalEntityAxis compact fist_S000006855Member column rr_ProspectusShareClassAxis compact * row primary compact * ~0.02250.000.000.000.01000.00<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://xbrl.sec.gov/rr/role/OperatingExpensesData column dei_LegalEntityAxis compact fist_S000006855Member column rr_ProspectusShareClassAxis compact * row primary compact * ~0.00420.00420.00420.00250.00650.000.00370.00370.00370.00010.00010.00010.01050.01450.0080-0.0024-0.0024-0.00240.00810.01210.0056ExampleThis 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 waiver and/or expense reimbursement by the investment manager and/or administrator for the 1 Year numbers only. Although your actual costs may be higher or lower, based on these assumptions your costs would be:3065287691458~ http://xbrl.sec.gov/rr/role/ExpenseExample column dei_LegalEntityAxis compact fist_S000006855Member column rr_ProspectusShareClassAxis compact * row primary compact * ~223435769171557231421968If you do not sell your shares:~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption column dei_LegalEntityAxis compact fist_S000006855Member column rr_ProspectusShareClassAxis compact * row primary compact * ~1234357691715Portfolio Turnover0.7551<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 75.51% of the average value of its portfolio.</p></div>Principal Investment StrategiesUnder normal market conditions, the Fund invests primarily in investment grade debt securities and investments, including government and corporate debt securities, mortgage- and asset-backed securities, investment grade corporate loans, municipal securities and futures with reference securities that are investment grade, targeting an estimated average portfolio duration of three (3) years or less.<div><p>Under normal market conditions, the Fund invests primarily in investment grade debt securities and investments, including government and corporate debt securities, mortgage- and asset-backed securities, investment grade corporate loans, municipal securities and futures with reference securities that are investment grade, targeting an estimated average portfolio duration of three (3) years or less. Duration is a measure of the expected price volatility of a debt instrument as a result of changes in market rates of interest, based on the weighted average timing of the instrument&#146;s expected principal and interest payments and other factors.</p><p>The Fund may also invest up to 20% of its total assets in non-investment grade debt securities, including up to 5% in securities rated lower than B by S&amp;P or Moody&#146;s, which may include defaulted securities. The Fund may invest up to 25% of its total assets in foreign securities, including up to 20% of its total assets in non-U.S. dollar denominated securities and up to 10% of its total assets in emerging market securities. The Fund's focus on the credit quality of its portfolio is intended to reduce credit risk and help to preserve the Fund's capital.</p><p>Mortgage-backed securities represent an interest in a pool of mortgage loans made by banks and other financial institutions to finance purchases of homes, commercial buildings and other real estate. The individual mortgage loans are packaged or "pooled" together for sale to investors. As the underlying mortgage loans are paid off, investors receive principal and interest payments. These securities may be fixed-rate or adjustable-rate mortgage-backed securities (ARMS). The Fund may also invest a small portion of its assets directly in mortgage loans. Many of the mortgage-backed securities in which the Fund invests are issued or guaranteed by the U.S. government, its agencies or instrumentalities, such as Ginnie Mae and U.S. government-sponsored entities, such as Fannie Mae and Freddie Mac; others are issued by private entities.</p><p>To pursue its investment goals, the Fund regularly enters into various derivative transactions, including currency and cross-currency forwards, currency, currency index, bond and interest rate futures contracts and options on interest rate futures contracts, and swap agreements, including interest rate, currency and credit default swaps, and options on interest rate and credit default swap agreements. The use of these derivative transactions may allow the Fund to obtain net long or short exposures to select currencies, interest rates, countries, duration or credit risks. These derivatives may be used to enhance Fund returns, increase liquidity, gain exposure to certain instruments or markets in a more efficient or less expensive way and/or hedge risks associated with its other portfolio investments.</p><p>In choosing investments, the Fund&#146;s investment manager selects securities in various market sectors based on the investment manager&#146;s assessment of changing economic, market, industry and issuer conditions. The investment manager uses a &#147;top-down&#148; analysis of macroeconomic trends, combined with a &#147;bottom-up&#148; fundamental analysis of market sectors, industries and issuers, to try to take advantage of varying sector reactions to economic events.</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>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. In general, securities with longer maturities are more sensitive to these interest rate changes.</p><p>Credit</p><p>An issuer of debt securities may fail to make interest payments and 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>Income</p><p>Because the Fund can only distribute what it earns, the Fund's distributions to shareholders may decline when prevailing interest rates fall or when the Fund experiences defaults on debt securities it holds.</p><p>High-Yield Debt Securities</p><p>Issuers of lower-rated or "high-yield" debt securities are not as strong financially as those issuing higher credit quality debt securities. These issuers are more likely to encounter financial difficulties and 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>Derivative Instruments</p><p>The performance of derivative instruments (including currency and credit related derivatives) depends largely on the performance of an underlying currency, security or index and such derivatives often have risks similar to their underlying instrument, in addition to other risks. Derivatives involve costs and can create economic leverage in the Fund's portfolio which may result in significant volatility and cause the Fund to participate in losses (as well as enable gains) in an amount that exceeds the Fund'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 used for hedging, the change in value of the derivative may also not correlate specifically with the currency, security or other risk being hedged. With over-the-counter derivatives, there is the risk that the other party to the transaction will fail to perform.</p><p>Mortgage-Backed Securities</p><p>Mortgage-backed securities differ from conventional debt securities because principal is paid back periodically over the life of the security rather than at maturity. The Fund may receive unscheduled prepayments of principal due to voluntary prepayments, refinancings or foreclosures on the underlying mortgage loans. Because of repayments, mortgage-backed securities may be less effective than some other types of debt securities as a means of "locking in" long-term interest rates and may have less potential for capital appreciation during periods of falling interest rates. A reduction in the anticipated rate of principal prepayments, especially during periods of rising interest rates, may increase or extend the effective maturity of mortgage-backed securities, making them more sensitive to interest rate changes, subject to greater price volatility, and more susceptible than some other debt securities to a decline in market value when interest rates rise.</p><p>Foreign Securities</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. The risks of investing in foreign securities are typically greater in less developed or emerging market countries.</p><p><b>Currency Management Strategies</b></p><p>Currency management strategies may substantially change the Fund&#146;s exposure to currency exchange rates and could result in losses to the Fund if currencies do not perform as the investment manager expects. In addition, currency management strategies, to the extent that they reduce the Fund&#146;s exposure to currency risks, may also reduce the Fund&#146;s ability to benefit from favorable changes in currency exchange rates. Using currency management strategies for purposes other than hedging further increases the Fund&#146;s exposure to foreign investment losses. Currency markets generally are not as regulated as securities markets. In addition, currency rates may fluctuate significantly over short periods of time, and can reduce returns.</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.</p><p>Market</p><p>The market values of securities owned by the Fund will go up or down, sometimes rapidly or unpredictably. A security&#146;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.</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></div>PerformanceThe 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.(800) DIAL BEN/342-5236franklintempleton.comSales 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>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 RETURNS0.01260.04260.05860.02320.08240.04790.0060~ http://xbrl.sec.gov/rr/role/BarChartData column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact fist_S000006855Member ~Best Quarter:2009-09-300.0287Worst Quarter:2011-09-30-0.0194<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">Q3'09</td><td style="border-bottom: 2px solid #ffffff;" valign="bottom" align="right">2.87%</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">-1.94%</td></tr></table><div><p>AVERAGE ANNUAL TOTAL RETURNS<br/>(figures reflect sales charges)</p><p>For the periods ended December 31, 2011</p></div>~ http://xbrl.sec.gov/rr/role/PerformanceTableData column dei_LegalEntityAxis compact fist_S000006855Member column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~Return Before Taxes-0.01690.03840.0347-0.02730.02530.0218-0.01090.02510.02200.00200.03820.03310.00820.04540.03960.01590.03990.03652004-11-172004-11-172004-11-172004-11-172004-11-17<div><p>Historical performance for Class C and Advisor Class shares prior to their inception is based on the performance of Class A shares. Class C and Advisor Class performance has been adjusted to reflect differences in sales charges and 12b-1 expenses (with respect to Class C only) between classes.</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>The Fund began offering Class C shares on October 1, 2012.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 investment manager and administrator have contractually agreed to waive or assume certain expenses so that common expenses (excluding the Rule 12b-1 fees and acquired fund fees and expenses) for each class of the Fund do not exceed 0.65% (other than certain non-routine expenses), until February 28, 2013. Effective October 1, 2012, the investment manager and fund administrator will lower this contractual common expense cap from 0.65% to 0.55%. The table reflects the cap after the change on October 1, 2012. The investment manager also has agreed in advance to reduce its fees as a result of the Fund's investment in a Franklin Templeton money fund (acquired fund) for at least the next 12-month period.The Fund began offering Advisor Class shares on May 15, 2008.