2.2.0.25truefalse06108 - Document - Risk/Return Summary {Unlabeled} (Principal LifeTime 2025 Fund)falsefalsefalse1falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : SummaryS000022104 Member {dei_LegalEntityAxis} : S000022104 Member 3/1/2011 - 3/1/2011 eol_0000898745-11-000126_STD_1_20110301_0_396770x-9996685_396840x-9994418http://www.sec.gov/CIK0000898745duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Fund (Prospectus Summary)dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_SummaryS000022104Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMember1false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.principal.com/role/riskreturn_s000022104member1falsefalsefalse00Principal LifeTime 2025 Fund (Prospectus Summary) | Principal LifeTime 2025 FundPrincipal LifeTime 2025 Fund (Prospectus Summary) | Principal LifeTime 2025 Fundfalsefalsefalsefalsefalse1falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : SummaryS000022104 Member {dei_LegalEntityAxis} : S000022104 Member 3/1/2011 - 3/1/2011 eol_0000898745-11-000126_STD_1_20110301_0_396770x-9996685_396840x-9994418http://www.sec.gov/CIK0000898745duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Fund (Prospectus Summary)dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_SummaryS000022104Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberOthernaNo definition available.No authoritative reference available.falsefalsePrincipal LifeTime 2025 Fund (Prospectus Summary) | Principal LifeTime 2025 Fund3false0rr_RiskReturnHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PRINCIPAL LIFETIME 2025 FUNDfalsefalsefalsefalsefalseOtherxbrli: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 falsefalseRisk/Return, Heading4false0ck0000898745_SupplementTextBlockck0000898745falsenadurationRisk/Return, Supplement Text Blockfalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>Supplement dated March 14, 2011 to the Class R-1, Class R-2, Class R-3, Class R-4 and Class R-5 Prospectus for Principal Funds, Inc. dated March 1, 2011 This supplement updates information currently in the Prospectus. Retain this supplement with the Prospectus. Replace the "Underlying Fund Risk" for the funds listed below: PRINCIPAL LIFETIME STRATEGIC INCOME FUND (page 111) PRINCIPAL LIFETIME 2010 FUND (page 116) PRINCIPAL LIFETIME 2015 FUND (page 121) PRINCIPAL LIFETIME 2020 FUND (page 126) PRINCIPAL LIFETIME 2025 FUND (page 131) PRINCIPAL LIFETIME 2030 FUND (page 136) PRINCIPAL LIFETIME 2035 FUND (page 141) PRINCIPAL LIFETIME 2040 FUND (page 146) PRINCIPAL LIFETIME 2045 FUND (page 151) PRINCIPAL LIFETIME 2050 FUND (page 156) PRINCIPAL LIFETIME 2055 FUND (page 161) STRATEGIC ASSET MANAGEMENT ("SAM") BALANCED PORTFOLIO (page 166) STRATEGIC ASSET MANAGEMENT ("SAM") CONSERVATIVE BALANCED PORTFOLIO (page 171) STRATEGIC ASSET MANAGEMENT ("SAM") CONSERVATIVE GROWTH PORTFOLIO (page 176) STRATEGIC ASSET MANAGEMENT ("SAM") FLEXIBLE INCOME PORTFOLIO (page 181) STRATEGIC ASSET MANAGEMENT ("SAM") STRATEGIC GROWTH PORTFOLIO (page 186) with the following: Underlying Fund Risk. 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.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringRisk/Return, Supplement Text BlockNo authoritative reference available.falsefalseRisk/Return, Supplement Text Block5false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>Underlying Fund Risk. 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.</pre>falsefalsefalsefalsefalseOtherus-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 falsefalseRisk, Narrative14Risk/Return Summary (Principal LifeTime 2025 Fund) (Principal LifeTime 2025 Fund (Prospectus Summary), Principal LifeTime 2025 Fund)UnKnownUnKnownUnKnownUnKnownfalsetrue