2.4.0.8040000 - Disclosure - Risk/Return Detail Data {Elements}truetruefalse1false falsefalseD2013Q1Sept13http://www.sec.gov/CIK0000898745duration2013-09-13T00:00:002013-09-13T00:00:001true 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_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-09-13falsefalsetruexbrli: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_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-09-13falsefalsetruexbrli: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_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-09-13falsefalsetruexbrli: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_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002012-12-28falsefalsetruexbrli: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 truefalseD2013Q1Sept13_dei_DocumentInformationDocumentAxis_ck0000898745_PFIProspectusInstitutionalClassSharesMemberhttp://www.sec.gov/CIK0000898745duration2013-09-13T00:00:002013-09-13T00:00:00falsefalsePFI 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 13, 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 December 28, 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 February 8, 2013, March 15, 2013, April 29, 2013, </font></div><div style="line-height:120%;padding-bottom:8px;text-align:center;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;">June 14, 2013 and July 31, 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%;text-align:center;font-size:10pt;"><font style="font-family:Arial;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 truefalseD2013Q1Sept13_dei_DocumentInformationDocumentAxis_ck0000898745_PFIProspectusInstitutionalClassSharesMember_dei_LegalEntityAxis_ck0000898745_S000037378Memberhttp://www.sec.gov/CIK0000898745duration2013-09-13T00:00:002013-09-13T00:00:00falsefalsePFI Prospectus - Institutional Class Sharesdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_PFIProspectusInstitutionalClassSharesMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseBlue Chip Fund [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000037378Memberdei_LegalEntityAxisexplicitMembernanafalse0PFI Prospectus - Institutional Class Shares | Blue Chip Fund [Member]14true 1rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:15false 2rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Blue Chip Fund falsefalsefalsexbrli: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_RiskHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Under the Principal Risks heading, after the Growth Stock Risk, add the following:falsefalsefalsexbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b false0Risk [Heading]17false 2rr_RiskNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:8px;text-align:left;font-size:10pt;"><font style="font-family:Arial;font-size:10pt;font-weight:bold;">Risk of Being an Underlying Fund. </font><font style="font-family:Arial;font-size:10pt;">A fund is subject to the risk of being an underlying fund to the extent that a fund of funds invests in the fund. An underlying fund of a fund of funds may experience relatively large redemptions or investments as the fund of funds periodically reallocates or rebalances its assets. These transactions may cause the underlying fund to sell portfolio securities to meet such redemptions, or to invest cash from such investments, at times it would not otherwise do so, and may as a result increase transaction costs and adversely affect underlying fund performance.</font></div></div>falsefalsefalseus-types:textBlockItemTypestringNarrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph i -Clause instruction -Subsection b false0Risk Narrative [Text Block]18false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse4false truefalseD2013Q1Sept13_dei_DocumentInformationDocumentAxis_ck0000898745_PFIProspectusInstitutionalClassSharesMember_dei_LegalEntityAxis_ck0000898745_S000032942Memberhttp://www.sec.gov/CIK0000898745duration2013-09-13T00:00:002013-09-13T00:00:00falsefalsePFI Prospectus - Institutional Class Sharesdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_PFIProspectusInstitutionalClassSharesMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseSmall-MidCap Dividend Income Fund [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000032942Memberdei_LegalEntityAxisexplicitMembernanafalse0PFI Prospectus - Institutional Class Shares | Small-MidCap Dividend Income Fund [Member]19true 1rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:20false 2rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Small-MidCap Dividend 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]21false 2rr_StrategyHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Under the Principal Investment Strategies heading, delete the paragraph 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]22false 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;">Under normal circumstances, the Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in dividend-paying equity securities of companies with small to medium market capitalizations at the time of each purchase. For this Fund, companies with small to medium market capitalizations are those with market capitalizations similar to companies in the Russell 2500 Value Index (as of June 30, 2013, the range of the index was between approximately $29.4 million and $13.0 billion). The Fund invests in value equity securities, an investment strategy that emphasizes buying equity securities that appear to be undervalued. The Fund invests in the securities of foreign issuers, real estate investment trusts, preferred securities, convertible securities, fixed-income securities, master limited partnerships, and royalty trusts.</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/RiskReturnDetailData122