<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.23.3</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>1239</ContextCount>
  <ElementCount>95</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>230</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000000 - Document - Document and Entity Information {Elements}</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DocumentDocumentandEntityInformationElements</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>000019 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Allocation Fund - Conservative (Class A C S I T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalAllocationFund-ConservativeClassACSITShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Allocation Fund - Conservative (Class A C S I T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>000029 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Allocation Fund - Moderate (Class A C S I T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalAllocationFund-ModerateClassACSITShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Allocation Fund - Moderate (Class A C S I T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>000039 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Allocation Fund - Growth (Class A C S I T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalAllocationFund-GrowthClassACSITShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Allocation Fund - Growth (Class A C S I T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>000049 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Allocation Fund - Conservative (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalAllocationFund-ConservativeClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Allocation Fund - Conservative (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>000059 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Allocation Fund - Moderate (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalAllocationFund-ModerateClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Allocation Fund - Moderate (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>000069 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Allocation Fund - Growth (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalAllocationFund-GrowthClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Allocation Fund - Growth (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>000079 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Absolute Return Income Opportunities Fund (Class A C S I N R T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonAbsoluteReturnIncomeOpportunitiesFundClassACSINRTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Absolute Return Income Opportunities Fund (Class A C S I N R T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>000089 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Developed World Bond Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonDevelopedWorldBondFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Developed World Bond Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>000099 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Flexible Bond Fund (Class A C S I N R T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonFlexibleBondFundClassACSINRTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Flexible Bond Fund (Class A C S I N R T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>000109 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Bond Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalBondFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Bond Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>000119 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson High-Yield Fund (Class A C S I N R T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonHigh-YieldFundClassACSINRTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson High-Yield Fund (Class A C S I N R T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>000129 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Multi-Sector Income Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonMulti-SectorIncomeFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Multi-Sector Income Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>000139 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Short Duration Flexible Bond Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonShortDurationFlexibleBondFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Short Duration Flexible Bond Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>000149 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Absolute Return Income Opportunities Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonAbsoluteReturnIncomeOpportunitiesFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Absolute Return Income Opportunities Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>000159 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Developed World Bond Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonDevelopedWorldBondFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Developed World Bond Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>000169 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Flexible Bond Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonFlexibleBondFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Flexible Bond Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>000179 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Global Bond Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGlobalBondFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Global Bond Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>000189 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson High-Yield Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonHigh-YieldFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson High-Yield Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>000199 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Multi-Sector Income Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonMulti-SectorIncomeFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Multi-Sector Income Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>000209 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Short Duration Flexible Bond Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonShortDurationFlexibleBondFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Short Duration Flexible Bond Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>000219 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Adaptive Global Allocation Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonAdaptiveGlobalAllocationFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Adaptive Global Allocation Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>000229 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Adaptive Global Allocation Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonAdaptiveGlobalAllocationFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Adaptive Global Allocation Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>000239 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Government Money Market Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGovernmentMoneyMarketFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Government Money Market Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>000249 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Money Market Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonMoneyMarketFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Money Market Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>000259 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Government Money Market Fund (Class T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonGovernmentMoneyMarketFundClassTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Government Money Market Fund (Class T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>000269 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Money Market Fund (Class T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonMoneyMarketFundClassTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Money Market Fund (Class T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>000279 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Adaptive Risk Managed U.S. Equity Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonAdaptiveRiskManagedU.S.EquityFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Adaptive Risk Managed U.S. Equity Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>000289 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Adaptive Risk Managed U.S. Equity Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonAdaptiveRiskManagedU.S.EquityFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Adaptive Risk Managed U.S. Equity Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>000299 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Mid Cap Value Fund (Class A C S I N R T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonMidCapValueFundClassACSINRTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Mid Cap Value Fund (Class A C S I N R T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>000309 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Responsible International Dividend Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonResponsibleInternationalDividendFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Responsible International Dividend Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>000319 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Small Cap Value Fund (Class A C S I N R T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonSmallCapValueFundClassACSINRTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Small Cap Value Fund (Class A C S I N R T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>000329 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Small-Mid Cap Value Fund (Class A C S I N T Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonSmall-MidCapValueFundClassACSINTShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Small-Mid Cap Value Fund (Class A C S I N T Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>000339 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Mid Cap Value Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonMidCapValueFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Mid Cap Value Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>000349 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Responsible International Dividend Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonResponsibleInternationalDividendFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Responsible International Dividend Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>000359 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Small Cap Value Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonSmallCapValueFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Small Cap Value Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>000369 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Small-Mid Cap Value Fund (Class D Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonSmall-MidCapValueFundClassDShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Small-Mid Cap Value Fund (Class D Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>000379 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Mid Cap Value Fund (Class L Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonMidCapValueFundClassLShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Mid Cap Value Fund (Class L Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>000389 - Disclosure - Risk/Return Detail Data {Elements} - Janus Henderson Small Cap Value Fund (Class L Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.janushenderson.com/role/DisclosureRiskReturnDetailDataElementsJanusHendersonSmallCapValueFundClassLShares</Role>
      <ShortName>Risk/Return Detail Data- Janus Henderson Small Cap Value Fund (Class L Shares)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="d520479d485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>040000 - Disclosure - Risk/Return Detail Data {Elements}</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/RiskReturnDetailData</Role>
      <ShortName>Risk/Return Detail Data</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="485BPOS" isN1a="true" isRR="true" isRRorOEF="true" original="d520479d485bpos.htm">d520479d485bpos.htm</File>
    <File>jif-20231027.xsd</File>
    <File>jif-20231027_cal.xml</File>
    <File>jif-20231027_def.xml</File>
    <File>jif-20231027_lab.xml</File>
    <File>jif-20231027_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>g520479assetcat_1.jpg</File>
    <File>g520479cov_tab.gif</File>
    <File>g520479img035b77f61.jpg</File>
    <File>g520479img0389bea82.jpg</File>
    <File>g520479img04047b384.jpg</File>
    <File>g520479img096706091.jpg</File>
    <File>g520479img0e0674808.jpg</File>
    <File>g520479img1c4fd9bb2.jpg</File>
    <File>g520479img1cf8ee6f1.jpg</File>
    <File>g520479img1ebb4c055.jpg</File>
    <File>g520479img24b0ca871.gif</File>
    <File>g520479img304054f57.jpg</File>
    <File>g520479img331d59091.jpg</File>
    <File>g520479img3ba8ca834.jpg</File>
    <File>g520479img3e3c4b3d3.jpg</File>
    <File>g520479img3f27c30a2.jpg</File>
    <File>g520479img41b0bc261.jpg</File>
    <File>g520479img424d461b1.gif</File>
    <File>g520479img4410dec33.jpg</File>
    <File>g520479img45fbf21b1.jpg</File>
    <File>g520479img47c9a7882.jpg</File>
    <File>g520479img5255c4602.jpg</File>
    <File>g520479img5362af0a2.jpg</File>
    <File>g520479img5818a2056.jpg</File>
    <File>g520479img59a030641.jpg</File>
    <File>g520479img5b2e8a302.jpg</File>
    <File>g520479img5c514bdc1.gif</File>
    <File>g520479img606aff932.jpg</File>
    <File>g520479img66c6741c3.jpg</File>
    <File>g520479img695a41472.jpg</File>
    <File>g520479img6a6519002.jpg</File>
    <File>g520479img6add397f1.jpg</File>
    <File>g520479img7ca5ceb02.jpg</File>
    <File>g520479img7f5794663.jpg</File>
    <File>g520479img8ae6c5297.jpg</File>
    <File>g520479img91ce2d302.jpg</File>
    <File>g520479img92840bad1.jpg</File>
    <File>g520479img94eb1d841.jpg</File>
    <File>g520479img970c41614.jpg</File>
    <File>g520479img97402f715.jpg</File>
    <File>g520479img9b8751093.jpg</File>
    <File>g520479img9e6a925d2.jpg</File>
    <File>g520479img9fa23a198.jpg</File>
    <File>g520479imga102e5c45.jpg</File>
    <File>g520479imgac40cea42.jpg</File>
    <File>g520479imgb27d2b382.jpg</File>
    <File>g520479imgbc951ba06.jpg</File>
    <File>g520479imgc012a57f4.jpg</File>
    <File>g520479imgcf48e8881.jpg</File>
    <File>g520479imgcf4ae16c4.jpg</File>
    <File>g520479imgd16f67c43.jpg</File>
    <File>g520479imgd3e0c5ed2.jpg</File>
    <File>g520479imgded10c8a1.gif</File>
    <File>g520479imge0d9f0453.jpg</File>
    <File>g520479imge9dd75551.jpg</File>
    <File>g520479imgf099acde4.jpg</File>
    <File>g520479imgf2a3dc1b5.jpg</File>
    <File>g520479imgf330b9fa1.jpg</File>
    <File>g520479imgf70bdfb22.jpg</File>
    <File>g520479imgf95e14353.jpg</File>
    <File>g520479imgfb3818393.jpg</File>
    <File>g520479janush_logo.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="128">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
    <BaseTaxonomy items="5837">http://xbrl.sec.gov/rr/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
