<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>165</ContextCount>
  <ElementCount>91</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>77</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentDocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>000011 - Document - Risk/Return Summary {Unlabeled} - Janus Flexible Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusFlexibleBondFund</Role>
      <ShortName>Risk/Return Summary  - Janus Flexible Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>000019 - Disclosure - Risk/Return Detail Data {Elements} - Janus Flexible Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusFlexibleBondFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Flexible Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>000021 - Document - Risk/Return Summary {Unlabeled} - Janus Global Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusGlobalBondFund</Role>
      <ShortName>Risk/Return Summary  - Janus Global Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>000029 - Disclosure - Risk/Return Detail Data {Elements} - Janus Global Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusGlobalBondFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Global Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>000031 - Document - Risk/Return Summary {Unlabeled} - Janus High-Yield Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusHigh-YieldFund</Role>
      <ShortName>Risk/Return Summary  - Janus High-Yield Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>000039 - Disclosure - Risk/Return Detail Data {Elements} - Janus High-Yield Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusHigh-YieldFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus High-Yield Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>000041 - Document - Risk/Return Summary {Unlabeled} - Janus Short-Term Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusShort-TermBondFund</Role>
      <ShortName>Risk/Return Summary  - Janus Short-Term Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>000049 - Disclosure - Risk/Return Detail Data {Elements} - Janus Short-Term Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusShort-TermBondFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Short-Term Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>000051 - Document - Risk/Return Summary {Unlabeled} - Perkins Large Cap Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledPerkinsLargeCapValueFund</Role>
      <ShortName>Risk/Return Summary  - Perkins Large Cap Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>000059 - Disclosure - Risk/Return Detail Data {Elements} - Perkins Large Cap Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsPerkinsLargeCapValueFund</Role>
      <ShortName>Risk/Return Detail Data  - Perkins Large Cap Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>000061 - Document - Risk/Return Summary {Unlabeled} - Perkins Mid Cap Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledPerkinsMidCapValueFund</Role>
      <ShortName>Risk/Return Summary  - Perkins Mid Cap Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>000069 - Disclosure - Risk/Return Detail Data {Elements} - Perkins Mid Cap Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsPerkinsMidCapValueFund</Role>
      <ShortName>Risk/Return Detail Data  - Perkins Mid Cap Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>000071 - Document - Risk/Return Summary {Unlabeled} - Perkins Select Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledPerkinsSelectValueFund</Role>
      <ShortName>Risk/Return Summary  - Perkins Select Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>000079 - Disclosure - Risk/Return Detail Data {Elements} - Perkins Select Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsPerkinsSelectValueFund</Role>
      <ShortName>Risk/Return Detail Data  - Perkins Select Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>000081 - Document - Risk/Return Summary {Unlabeled} - Perkins Small Cap Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledPerkinsSmallCapValueFund</Role>
      <ShortName>Risk/Return Summary  - Perkins Small Cap Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>000089 - Disclosure - Risk/Return Detail Data {Elements} - Perkins Small Cap Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsPerkinsSmallCapValueFund</Role>
      <ShortName>Risk/Return Detail Data  - Perkins Small Cap Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>000091 - Document - Risk/Return Summary {Unlabeled} - Perkins Value Plus Income Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledPerkinsValuePlusIncomeFund</Role>
      <ShortName>Risk/Return Summary  - Perkins Value Plus Income Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>000099 - Disclosure - Risk/Return Detail Data {Elements} - Perkins Value Plus Income Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsPerkinsValuePlusIncomeFund</Role>
      <ShortName>Risk/Return Detail Data  - Perkins Value Plus Income Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>000101 - Document - Risk/Return Summary {Unlabeled} - Janus Emerging Markets Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusEmergingMarketsFund</Role>
      <ShortName>Risk/Return Summary  - Janus Emerging Markets Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>000109 - Disclosure - Risk/Return Detail Data {Elements} - Janus Emerging Markets Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusEmergingMarketsFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Emerging Markets Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>000111 - Document - Risk/Return Summary {Unlabeled} - Janus Global Research Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusGlobalResearchFund</Role>
      <ShortName>Risk/Return Summary  - Janus Global Research Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>000119 - Disclosure - Risk/Return Detail Data {Elements} - Janus Global Research Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusGlobalResearchFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Global Research Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>000121 - Document - Risk/Return Summary {Unlabeled} - Janus Global Select Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusGlobalSelectFund</Role>
      <ShortName>Risk/Return Summary  - Janus Global Select Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>000129 - Disclosure - Risk/Return Detail Data {Elements} - Janus Global Select Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusGlobalSelectFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Global Select Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>000131 - Document - Risk/Return Summary {Unlabeled} - Janus International Equity Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/role/DocumentRiskReturnSummaryUnlabeledJanusInternationalEquityFund</Role>
      <ShortName>Risk/Return Summary  - Janus International Equity Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>000139 - Disclosure - Risk/Return Detail Data {Elements} - Janus International Equity Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusInternationalEquityFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus International Equity Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>000141 - Document - Risk/Return Summary {Unlabeled} - Janus Overseas Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusOverseasFund</Role>
      <ShortName>Risk/Return Summary  - Janus Overseas Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>000149 - Disclosure - Risk/Return Detail Data {Elements} - Janus Overseas Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusOverseasFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Overseas Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>000151 - Document - Risk/Return Summary {Unlabeled} - Janus Worldwide Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusWorldwideFund</Role>
      <ShortName>Risk/Return Summary  - Janus Worldwide Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>000159 - Disclosure - Risk/Return Detail Data {Elements} - Janus Worldwide Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusWorldwideFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Worldwide Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>000161 - Document - Risk/Return Summary {Unlabeled} - Janus Balanced Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusBalancedFund</Role>
      <ShortName>Risk/Return Summary  - Janus Balanced Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>000169 - Disclosure - Risk/Return Detail Data {Elements} - Janus Balanced Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusBalancedFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Balanced Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>000171 - Document - Risk/Return Summary {Unlabeled} - Janus Contrarian Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusContrarianFund</Role>
      <ShortName>Risk/Return Summary  - Janus Contrarian Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>000179 - Disclosure - Risk/Return Detail Data {Elements} - Janus Contrarian Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusContrarianFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Contrarian Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>000181 - Document - Risk/Return Summary {Unlabeled} - Janus Enterprise Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusEnterpriseFund</Role>
      <ShortName>Risk/Return Summary  - Janus Enterprise Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>000189 - Disclosure - Risk/Return Detail Data {Elements} - Janus Enterprise Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusEnterpriseFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Enterprise Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>000191 - Document - Risk/Return Summary {Unlabeled} - Janus Forty Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusFortyFund</Role>
      <ShortName>Risk/Return Summary  - Janus Forty Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>000199 - Disclosure - Risk/Return Detail Data {Elements} - Janus Forty Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusFortyFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Forty Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>000201 - Document - Risk/Return Summary {Unlabeled} - Janus Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusFund</Role>
      <ShortName>Risk/Return Summary  - Janus Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>000209 - Disclosure - Risk/Return Detail Data {Elements} - Janus Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>000211 - Document - Risk/Return Summary {Unlabeled} - Janus Growth and Income Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusGrowthandIncomeFund</Role>
      <ShortName>Risk/Return Summary  - Janus Growth and Income Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>000219 - Disclosure - Risk/Return Detail Data {Elements} - Janus Growth and Income Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusGrowthandIncomeFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Growth and Income Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>000221 - Document - Risk/Return Summary {Unlabeled} - Janus Research Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusResearchFund</Role>
      <ShortName>Risk/Return Summary  - Janus Research Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>000229 - Disclosure - Risk/Return Detail Data {Elements} - Janus Research Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusResearchFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Research Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>000231 - Document - Risk/Return Summary {Unlabeled} - Janus Triton Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusTritonFund</Role>
      <ShortName>Risk/Return Summary  - Janus Triton Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R137.htm</HtmlFileName>
      <LongName>000239 - Disclosure - Risk/Return Detail Data {Elements} - Janus Triton Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusTritonFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Triton Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R138.htm</HtmlFileName>
      <LongName>000241 - Document - Risk/Return Summary {Unlabeled} - Janus Venture Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledJanusVentureFund</Role>
      <ShortName>Risk/Return Summary  - Janus Venture Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R143.htm</HtmlFileName>
      <LongName>000249 - Disclosure - Risk/Return Detail Data {Elements} - Janus Venture Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsJanusVentureFund</Role>
      <ShortName>Risk/Return Detail Data  - Janus Venture Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R144.htm</HtmlFileName>
      <LongName>000251 - Document - Risk/Return Summary {Unlabeled} - Perkins Global Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DocumentRiskReturnSummaryUnlabeledPerkinsGlobalValueFund</Role>
      <ShortName>Risk/Return Summary  - Perkins Global Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R149.htm</HtmlFileName>
      <LongName>000259 - Disclosure - Risk/Return Detail Data {Elements} - Perkins Global Value Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.finra.org/Role/DisclosureRiskReturnDetailDataElementsPerkinsGlobalValueFund</Role>
      <ShortName>Risk/Return Detail Data  - Perkins Global Value Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R150.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>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs />
  <InputFiles>
    <File>jif2-20120530.xml</File>
    <File>jif2-20120530.xsd</File>
    <File>jif2-20120530_cal.xml</File>
    <File>jif2-20120530_def.xml</File>
    <File>jif2-20120530_lab.xml</File>
    <File>jif2-20120530_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>BarChart1.jpg</File>
    <File>BarChart2.jpg</File>
    <File>BarChart3.jpg</File>
    <File>BarChart4.jpg</File>
    <File>BarChart5.jpg</File>
    <File>BarChart6.jpg</File>
    <File>BarChart7.jpg</File>
    <File>BarChart8.jpg</File>
    <File>BarChart9.jpg</File>
    <File>BarChart10.jpg</File>
    <File>BarChart11.jpg</File>
    <File>BarChart12.jpg</File>
    <File>BarChart13.jpg</File>
    <File>BarChart14.jpg</File>
    <File>BarChart15.jpg</File>
    <File>BarChart16.jpg</File>
    <File>BarChart17.jpg</File>
    <File>BarChart18.jpg</File>
    <File>BarChart19.jpg</File>
    <File>BarChart20.jpg</File>
    <File>BarChart21.jpg</File>
    <File>BarChart22.jpg</File>
    <File>BarChart23.jpg</File>
    <File>BarChart24.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
