2.2.0.25truefalse040000 - Disclosure - Risk/Return Detail Data {Elements}truetruefalse1falsefalsefalsefalse1/29/2010 - 1/28/2011 TwelveMonthsEnded_28Jan2011http://www.sec.gov/CIK0000277751duration2010-01-29T00:00:002011-01-28T00:00:002true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:3false0dei_DocumentTypedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00OtherfalsefalsefalsefalsefalseOtherus-types:SECReportItemTypenaThe type of document being provided (such as 10-K, 10-Q, N-1A, etc). The document type should be limited to the same value as the supporting SEC submission type. The acceptable values are as follows: S-1, S-3, S-4, S-11, F-1, F-3, F-4, F-9, F-10, 6-K, 8-K, 10, 10-K, 10-Q, 20-F, 40-F, N-1A, 485BPOS, NCSR, N-Q, and Other.No authoritative reference available.falsefalseDocument Type4false0dei_DocumentPeriodEndDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002010-09-30falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements this will be the filing date. The format of the date is CCYY-MM-DD.No authoritative reference available.falsefalseDocument Period End Date5false0dei_EntityRegistrantNamedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00JANUS INVESTMENT FUNDfalsefalsefalsefalsefalseOtherxbrli:normalizedStringItemTypenormalizedstringThe exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 falsefalseRegistrant Name6false0dei_EntityCentralIndexKeydeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse000000277751falsefalsefalsefalsefalseOtherus-types:centralIndexKeyItemTypenaA unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 falsefalseCentral Index Key7false0dei_AmendmentFlagdeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalsefalseOtherxbrli:booleanItemTypenaIf the value is true, then the document as an amendment to previously-filed/accepted document.No authoritative reference available.falsefalseAmendment Flag8false0dei_DocumentCreationDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-03-03falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.No authoritative reference available.falsefalseDocument Creation Date9false0dei_DocumentEffectiveDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-03-03falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.No authoritative reference available.falsefalseDocument Effective Date10false0rr_ProspectusDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-01-28falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe date of the prospectus.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 1 -Paragraph 3 -Subsection a falsefalseProspectus Date11false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://janus.com/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : Janus Worldwide Fund [Member] {dei_LegalEntityAxis} : Global & International - Class A, C, S, I, R and T Shares [Member] 1/29/2010 - 1/28/2011 TwelveMonthsEnded_28Jan2011_S000010489_Member_Prospectus_One_Memberhttp://www.sec.gov/CIK0000277751duration2010-01-29T00:00:002011-01-28T00:00:00falsefalseJanus Worldwide Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldijif277751_S000010489Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseGlobal & International - Class A, C, S, I, R and T Shares [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldijif277751_ProspectusOneMemberdei_LegalEntityAxisexplicitMemberOthernaNo definition available.No authoritative reference available.falsefalseJanus Worldwide Fund [Member] | Global & International - Class A, C, S, I, R and T Shares [Member]12true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:13false0jif277751_SupplementTextBlockjif277751falsenadurationSupplement.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00Janus Investment FundJanus Worldwide FundSupplement dated March 3, 2011 to Currently Effective ProspectusesEffective May 16, 2011, the following changes apply as noted.falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringSupplement.No authoritative reference available.falsefalseSupplement [Text Block]14false0jif277751_SupplementObjectiveTextBlockjif277751falsenadurationSupplement Objective.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse001. The following replaces the corresponding information in its entirety under “Investment Objective” in the Fund Summary section of the Prospectus for the Fund:falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringSupplement Objective.No authoritative reference available.falsefalseSupplement Objective [Text Block]15false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Janus Worldwide Fund seeks long-term growth of capital.falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective, Primary [Text Block]16false0jif277751_SupplementPrincipalInvestmentStrategyTextBlockjif277751falsenadurationSupplement Principal Investment Strategy.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002. The following replaces the corresponding information under “Principal Investment Strategies” in the Fund Summary section of the Prospectus for the Fund: Principal Investment StrategiesThe Fund pursues its investment objective by investing primarily in equity securities, which include, but are not limited to, common stocks, preferred stocks, and depositary receipts of companies of any size located throughout the world. The Fund normally invests in issuers from several different countries, including the United States. The Fund may, under unusual circumstances, invest in a single country. The Fund may have significant exposure to emerging markets. The Fund may also invest in foreign equity and debt securities.The portfolio manager applies a “bottom up” approach in choosing investments. In other words, the portfolio manager looks at companies one at a time to determine if a company is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.The Fund may invest a significant portion of its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as stocks, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund intends to invest in derivative instruments (by taking long and/or short positions) including, but not limited to, put and call options, swaps, and forward currency contracts to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund, and to earn income and enhance returns. The Fund may also invest in derivative instruments for other purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions).falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringSupplement Principal Investment Strategy.No authoritative reference available.falsefalseSupplement Principal Investment Strategy [Text Block]17false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://janus.com/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse3falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : Janus Worldwide Fund [Member] {dei_LegalEntityAxis} : Global & International - Class D Shares [Member] 1/29/2010 - 1/28/2011 TwelveMonthsEnded_28Jan2011_S000010489_Member_Prospectus_Two_Memberhttp://www.sec.gov/CIK0000277751duration2010-01-29T00:00:002011-01-28T00:00:00falsefalseJanus Worldwide Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldijif277751_S000010489Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseGlobal & International - Class D Shares [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldijif277751_ProspectusTwoMemberdei_LegalEntityAxisexplicitMemberOthernaNo definition available.No authoritative reference available.falsefalseJanus Worldwide Fund [Member] | Global & International - Class D Shares [Member]18true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:19false0jif277751_SupplementTextBlockjif277751falsenadurationSupplement.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00Janus Investment FundJanus Worldwide FundSupplement dated March 3, 2011 to Currently Effective ProspectusesEffective May 16, 2011, the following changes apply as noted.falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringSupplement.No authoritative reference available.falsefalseSupplement [Text Block]20false0jif277751_SupplementObjectiveTextBlockjif277751falsenadurationSupplement Objective.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse001. The following replaces the corresponding information in its entirety under “Investment Objective” in the Fund Summary section of the Prospectus for the Fund:falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringSupplement Objective.No authoritative reference available.falsefalseSupplement Objective [Text Block]21false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Janus Worldwide Fund seeks long-term growth of capital.falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective, Primary [Text Block]22false0jif277751_SupplementPrincipalInvestmentStrategyTextBlockjif277751falsenadurationSupplement Principal Investment Strategy.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse002. The following replaces the corresponding information under “Principal Investment Strategies” in the Fund Summary section of the Prospectus for the Fund: Principal Investment StrategiesThe Fund pursues its investment objective by investing primarily in equity securities, which include, but are not limited to, common stocks, preferred stocks, and depositary receipts of companies of any size located throughout the world. The Fund normally invests in issuers from several different countries, including the United States. The Fund may, under unusual circumstances, invest in a single country. The Fund may have significant exposure to emerging markets. The Fund may also invest in foreign equity and debt securities.The portfolio manager applies a “bottom up” approach in choosing investments. In other words, the portfolio manager looks at companies one at a time to determine if a company is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.The Fund may invest a significant portion of its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as stocks, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund intends to invest in derivative instruments (by taking long and/or short positions) including, but not limited to, put and call options, swaps, and forward currency contracts to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund, and to earn income and enhance returns. The Fund may also invest in derivative instruments for other purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions).falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringSupplement Principal Investment Strategy.No authoritative reference available.falsefalseSupplement Principal Investment Strategy [Text Block]121Risk/Return Detail DataUnKnownUnKnownUnKnownUnKnownfalsetrue