2.4.0.8040000 - Disclosure - Risk/Return Detail Data {Elements}truetruefalse1false falsefalseD2013Q1Sept20http://www.sec.gov/CIK0000898745duration2013-09-20T00:00:002013-09-20T00:00:001true 1rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:2false 2dei_DocumentTypedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Otherfalsefalsefalseus-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 definition available.false0Document Type3false 2dei_DocumentPeriodEndDatedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-09-20falsefalsetruexbrli: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 definition available.false0Document Period End Date4false 2dei_EntityRegistrantNamedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PRINCIPAL FUNDS INCfalsefalsefalsexbrli: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 false0Registrant Name5false 2dei_EntityCentralIndexKeydei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse000000898745falsefalsefalseus-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 false0Central Index Key6false 2dei_AmendmentFlagdei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsexbrli:booleanItemTypenaIf the value is true, then the document as an amendment to previously-filed/accepted document.No definition available.false0Amendment Flag7false 2dei_DocumentCreationDatedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-09-20falsefalsetruexbrli: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 definition available.false0Document Creation Date8false 2dei_DocumentEffectiveDatedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-09-20falsefalsetruexbrli: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 definition available.false0Document Effective Date9false 2rr_ProspectusDaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-03-01falsefalsetruexbrli:dateItemTypedateThe date of the prospectus.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 1 -Paragraph 3 -Subsection a false0Prospectus Date10false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false truefalseD2013Q1Sept20_dei_DocumentInformationDocumentAxis_ck0000898745_PFIProspectusInstitutionalClassSharesMemberhttp://www.sec.gov/CIK0000898745duration2013-09-20T00:00:002013-09-20T00:00:00falsefalsePFI Prospectus - Institutional Class Sharesdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_PFIProspectusInstitutionalClassSharesMemberdei_DocumentInformationDocumentAxisexplicitMembernanafalse0PFI Prospectus - Institutional Class Shares11true 1rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:12false 2ck0000898745_SupplementTextBlockck0000898745_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;font-weight:bold;">Supplement dated September 20, 2013</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;font-weight:bold;">to the Classes Institutional, R-1, R-2, R-3, R-4, and R-5 Shares Prospectus</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;font-weight:bold;">for Principal Funds, Inc.</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;font-weight:bold;">dated March 1, 2013</font></div><div style="line-height:120%;text-align:left;text-indent:48px;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;">&#160;&#160;&#160;&#160;</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;">(as supplemented on March 28, 2013, April 2, 2013, April 17, 2013, May 9, 2013, </font></div><div style="line-height:120%;padding-bottom:10px;text-align:center;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;">June 14, 2013 and September 13, 2013)</font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;">This supplement updates information currently in the Prospectus. Retain this supplement with the Prospectus.</font></div><div style="line-height:120%;padding-bottom:4px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;padding-bottom:16px;text-align:left;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;font-weight:bold;">FUND SUMMARIES</font></div></div>falsefalsefalseus-types:textBlockItemTypestringSupplement [Text Block]No definition available.false0Supplement [Text Block]13false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse3false truefalseD2013Q1Sept20_dei_DocumentInformationDocumentAxis_ck0000898745_PFIProspectusInstitutionalClassSharesMember_dei_LegalEntityAxis_ck0000898745_S000024296Memberhttp://www.sec.gov/CIK0000898745duration2013-09-20T00:00:002013-09-20T00:00:00falsefalsePFI Prospectus - Institutional Class Sharesdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_PFIProspectusInstitutionalClassSharesMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseGlobal Diversified Income Fund [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000024296Memberdei_LegalEntityAxisexplicitMembernanafalse0PFI Prospectus - Institutional Class Shares | Global Diversified Income Fund [Member]14true 1rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:15false 2rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Global Diversified Income Fundfalsefalsefalsexbrli:stringItemTypestringRisk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicatedReference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 false0Risk/Return [Heading]16false 2rr_StrategyHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00On or about November 6, 2013, under the Principal Investment Strategies heading, delete the paragraph that begins “A portion of the Fund's assets is invested in publicly-listed infrastructure companies” and substitute:falsefalsefalsexbrli:stringItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a false0Strategy [Heading]17false 2rr_StrategyNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;">A portion of the Fund's assets is invested in publicly-listed infrastructure companies (domestic and foreign public utility, energy, and transportation companies). Publicly-listed infrastructure equity securities trade on an exchange and include companies involved to a significant extent in providing products, services or equipment for: transportation (including toll roads, airports, railways, and ports); the generation, transmission or distribution of electricity, gas or water (utilities); or telecommunications activities as well as in companies involved in the discovery, development, production, generation, transmission, refinement, measurement, trading, marketing or distribution of energy.</font></div></div>falsefalsefalseus-types:textBlockItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a false0Strategy Narrative [Text Block]falseRisk/Return Detail DataUnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://xbrl.sec.gov/rr/role/RiskReturnDetailData117