2.4.1.9 Html 106 85 1 true 57 0 false 4 false false R1.htm 000000 - Document - Document and Entity Information {Elements} Sheet http://www.proofPlus.com/role/DocumentInformation Document and Entity Information false true R2.htm 000001 - Document - Risk/Return Summary {Unlabeled} - Franklin Balanced Fund Sheet http://www.proofPlus.com/role/SummaryS000012705_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Summary - Franklin Balanced Fund false false R9.htm 000009 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Balanced Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000012705_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Detail Data - Franklin Balanced Fund false true R10.htm 000010 - Document - Risk/Return Summary {Unlabeled} - Franklin Convertible Securities Fund Sheet http://www.proofPlus.com/role/SummaryS000006851_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Summary - Franklin Convertible Securities Fund false false R17.htm 000018 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Convertible Securities Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000006851_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Detail Data - Franklin Convertible Securities Fund false true R18.htm 000019 - Document - Risk/Return Summary {Unlabeled} - Franklin Equity Income Fund Sheet http://www.proofPlus.com/role/SummaryS000006852_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Summary - Franklin Equity Income Fund false false R25.htm 000027 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Equity Income Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000006852_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Detail Data - Franklin Equity Income Fund false true R26.htm 000028 - Document - Risk/Return Summary {Unlabeled} - Franklin Real Return Fund Sheet http://www.proofPlus.com/role/SummaryS000006856_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Summary - Franklin Real Return Fund false false R33.htm 000036 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Real Return Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000006856_FranklinInvestorsSecuritiesTrustFIST115 Risk/Return Detail Data - Franklin Real Return Fund false true R34.htm 000037 - Document - Risk/Return Summary {Unlabeled} - Franklin Adjustable U.S. Government Securities Fund Sheet http://www.proofPlus.com/role/SummaryS000006850_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Summary - Franklin Adjustable U.S. Government Securities Fund false false R41.htm 000045 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Adjustable U.S. Government Securities Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000006850_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Detail Data - Franklin Adjustable U.S. Government Securities Fund false true R42.htm 000046 - Document - Risk/Return Summary {Unlabeled} - Franklin Floating Rate Daily Access Fund Sheet http://www.proofPlus.com/role/SummaryS000006853_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Summary - Franklin Floating Rate Daily Access Fund false false R49.htm 000054 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Floating Rate Daily Access Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000006853_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Detail Data - Franklin Floating Rate Daily Access Fund false true R50.htm 000055 - Document - Risk/Return Summary {Unlabeled} - Franklin Low Duration Total Return Fund Sheet http://www.proofPlus.com/role/SummaryS000006855_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Summary - Franklin Low Duration Total Return Fund false false R57.htm 000063 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Low Duration Total Return Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000006855_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Detail Data - Franklin Low Duration Total Return Fund false true R58.htm 000064 - Document - Risk/Return Summary {Unlabeled} - Franklin Total Return Fund Sheet http://www.proofPlus.com/role/SummaryS000006857_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Summary - Franklin Total Return Fund false false R65.htm 000072 - Disclosure - Risk/Return Detail Data {Elements} - Franklin Total Return Fund Sheet http://www.proofPlus.com/role/DisclosureDetailS000006857_FranklinInvestorsSecuritiesTrustFIST217 Risk/Return Detail Data - Franklin Total Return Fund false false R66.htm 040000 - Disclosure - Risk/Return Detail Data {Elements} Sheet http://xbrl.sec.gov/rr/role/RiskReturnDetailData Risk/Return Detail Data true false All Reports Book All Reports fist-20150301.xml fist-20150301.xsd fist-20150301_cal.xml fist-20150301_def.xml fist-20150301_lab.xml fist-20150301_pre.xml BarChart1.jpg BarChart2.jpg BarChart3.jpg BarChart4.jpg BarChart5.jpg BarChart6.jpg BarChart7.jpg BarChart8.jpg true true