2.2.0.25truefalse061200 - Document - Risk/Return Summary {Unlabeled} (Principal LifeTime 2025 Fund)falsefalsetrue1falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : SummaryS000022104 Member {dei_LegalEntityAxis} : S000022104 Member 3/1/2011 - 3/1/2011 eol_0000898745-11-000043_STD_1_20110301_0_396770x-9996685_396840x-9994418http://www.sec.gov/CIK0000898745duration2011-03-01T00:00:002011-03-01T00:00:00falsefalseck0000898745_SummaryS000022104Memberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_SummaryS000022104Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseck0000898745_S000022104Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure01false0natruenanaNo 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_0000898745-11-000043_STD_1_20110301_0_396770x-9996685_396840x-9994418http://www.sec.gov/CIK0000898745duration2011-03-01T00:00:002011-03-01T00:00:00falsefalseck0000898745_SummaryS000022104Memberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_SummaryS000022104Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseck0000898745_S000022104Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0OthernaNo 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, Heading4false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Objective:falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInvestment 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 falsefalseInvestment Objective, Heading5false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The Fund seeks a total return consisting of long-term growth of capital and current income.</pre>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 falsefalseinvestment Objective, Primary6false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Fees and Expenses of the FundfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Fee Table Includes the following information, in plain English under rule 421(d) under the Securities Act, after Item 2 Fees and expenses of the Fund This table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Shareholder Fees (fees paid directly from your investment) Example This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be You would pay the following expenses if you did not redeem your shares The Example does not reflect sales charges (loads) on reinvested dividends [and other distributions]. If these sales charges (loads) were included, your costs would be higher. Portfolio Turnover The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was __% of the average value of its whole portfolio. Instructions. A.3.instructions.6 New Funds. For purposes of this Item, a "New Fund" is a Fund that does not include in Form N-1A financial statements reporting operating results or that includes financial statements for the Fund's initial fiscal year reporting operating results for a period of 6 months or less. The following Instructions apply to New Funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph d -Subsection instructions falsefalseExpense, Heading7false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. The Fund operates as a fund of funds and thus bears both its own expenses and, indirectly, its proportionate share of the expenses of the underlying funds in which it invests.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThis table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown.The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense, Narrative8false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Shareholder Fees (fees paid directly from your investment): NonefalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringShareholder Fees (fees paid directly from your investment).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subsection table falsefalseShareholder Fees, Caption9false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 7 -Subsection table falsefalseOperating Expenses, Caption10false0rr_AnnualFundOperatingExpensesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.principal.com/role/OperatingExpensesData_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display:none">~ http://www.principal.com/role/OperatingExpensesData_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://www.principal.com/role/OperatingExpensesData_S000022104Memberfalsefalse061201 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Fund - R-1rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_C000063432Memberrr_ProspectusShareClassAxisexplicitMemberPrincipal LifeTime 2025 FundPrincipal LifeTime 2025 Fund - R-1iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$2falseColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Fund - 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Under an appropriate caption or a subcaption of "Other Expenses," disclose the amount of any distribution or similar expenses deducted from the Fund's assets other than pursuant to a rule 12b-1 plan.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 9 -Subsection table falsefalseDistribution and/or Service (12b-1) Fees0rr_DistributionAndService12b1FeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00350.0035falsefalsefalsetruefalse2truetruetrue0.00300.0030falsefalsefalsetruefalse3truetruetrue0.00250.0025falsefalsefalsetruefalse4truetruetrue0.00100.0010falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsefalsefalseOthernanafalsefalseDistribution and/or Service (12b-1) Fees3falseRowprimaryElement*5false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00540.0054falsefalsefalsetruefalse2truetruetrue0.00460.0046falsefalsefalsetruefalse3truetruetrue0.00330.0033falsefalsefalsetruefalse4truetruetrue0.00290.0029falsefalsefalsetruefalse5truetruetrue0.00270.0027falsefalsefalsetruefalseOtherrr:NonNegativePure4Typepure"Other Expenses" include all expenses not otherwise disclosed in the table that are deducted from the Fund's assets or charged to all shareholder accounts. The amount of expenses deducted from the Fund's assets are the amounts shown as expenses in the Fund's statement of operations (including increases resulting from complying with paragraph 2(g) of rule 6-07 of Regulation S-X [17 CFR 210.6-07]). "Other Expenses" do not include extraordinary expenses as determined under generally accepted accounting principles (see Accounting Principles Board Opinion No. 30). If extraordinary expenses were incurred that materially affected the Fund's "Other Expenses," disclose in a footnote to the table what "Other Expenses" would have been had the extraordinary expenses been included.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph c -Clause i -Subsection instructions falsefalseOther Expenses0rr_OtherExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00540.0054falsefalsefalsetruefalse2truetruetrue0.00460.0046falsefalsefalsetruefalse3truetruetrue0.00330.0033falsefalsefalsetruefalse4truetruetrue0.00290.0029falsefalsefalsetruefalse5truetruetrue0.00270.0027falsefalsefalsetruefalseOthernanafalsefalseOther Expenses4falseRowprimaryElement*6false0rr_AcquiredFundFeesAndExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00720.0072falsefalsefalsetruefalse2truetruetrue0.00720.0072falsefalsefalsetruefalse3truetruetrue0.00720.0072falsefalsefalsetruefalse4truetruetrue0.00720.0072falsefalsefalsetruefalse5truetruetrue0.00720.0072falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table falsefalseAcquired Fund Fees and Expenses0rr_AcquiredFundFeesAndExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00720.0072falsefalsefalsetruefalse2truetruetrue0.00720.0072falsefalsefalsetruefalse3truetruetrue0.00720.0072falsefalsefalsetruefalse4truetruetrue0.00720.0072falsefalsefalsetruefalse5truetruetrue0.00720.0072falsefalsefalsetruefalseOthernanafalsefalseAcquired Fund Fees and Expenses5falseRowprimaryElement*7false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01640.0164falsefalsefalsetruefalse2truetruetrue0.01510.0151falsefalsefalsetruefalse3truetruetrue0.01330.0133falsefalsefalsetruefalse4truetruetrue0.01140.0114falsefalsefalsetruefalse5truetruetrue0.01020.0102falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses. If the Fund is a Feeder Fund, reflect the aggregate expenses of the Feeder Fund and the Master Fund in a single fee table using the captions provided. In a footnote to the fee table, state that the table and Example reflect the expenses of both the Feeder and Master Funds. If the prospectus offers more than one Class of a Multiple Class Fund or more than one Feeder Fund that invests in the same Master Fund, provide a separate response for each Class or Feeder Fund. Base the percentages of "Annual Fund Operating Expenses" on amounts incurred during the Fund's most recent fiscal year, but include in expenses amounts that would have been incurred absent expense reimbursement or fee waiver arrangements. If the Fund has changed its fiscal year and, as a result, the most recent fiscal year is less than three months, use the fiscal year prior to the most recent fiscal year as the basis for determining "Annual Fund Operating Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph d -Subsection instructions falsefalseTotal Annual Fund Operating Expenses0rr_ExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01640.0164falsefalsefalsetruefalse2truetruetrue0.01510.0151falsefalsefalsetruefalse3truetruetrue0.01330.0133falsefalsefalsetruefalse4truetruetrue0.01140.0114falsefalsefalsetruefalse5truetruetrue0.01020.0102falsefalsefalsetruefalseOthernanafalsefalseTotal Annual Fund Operating Expenses55Annual Fund Operating Expenses Principal LifeTime 2025 FundUnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No authoritative reference available.falsefalseAnnual Fund Operating Expenses [Table]11false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00ExamplefalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalseExpense Example, Heading12false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThe Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection example falsefalseExpense Example, Narrative13false0rr_ExpenseExampleWithRedemptionTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.principal.com/role/ExpenseExample_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display:none">~ http://www.principal.com/role/ExpenseExample_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>truehttp://www.principal.com/role/ExpenseExample_S000022104Memberfalsefalse061202 - Schedule - Expense Example {Transposed}truefalsefalse1falseColumnprimaryElement*3false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue167167falsefalsefalsetruefalse2truefalsetrue154154falsefalsefalsetruefalse3truefalsetrue135135falsefalsefalsetruefalse4truefalsetrue116116falsefalsefalsetruefalse5truefalsetrue104104falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalseExpense Example, With Redemption, 1 YearfalseUSDfalsefalse$2falseColumnprimaryElement*4false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue517517falsefalsefalsetruefalse2truefalsetrue477477falsefalsefalsetruefalse3truefalsetrue421421falsefalsefalsetruefalse4truefalsetrue362362falsefalsefalsetruefalse5truefalsetrue325325falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalseExpense Example, With Redemption, 3 YearsfalseUSDfalsefalse$3falseColumnprimaryElement*5false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue892892falsefalsefalsetruefalse2truefalsetrue824824falsefalsefalsetruefalse3truefalsetrue729729falsefalsefalsetruefalse4truefalsetrue628628falsefalsefalsetruefalse5truefalsetrue563563falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalseExpense Example, With Redemption, 5 YearsfalseUSDfalsefalse$4falseColumnprimaryElement*6false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue19441944falsefalsefalsetruefalse2truefalsetrue18021802falsefalsefalsetruefalse3truefalsetrue16011601falsefalsefalsetruefalse4truefalsetrue13861386falsefalsefalsetruefalse5truefalsetrue12481248falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalseExpense Example, With Redemption, 10 YearsfalseUSDfalsefalse$1falseRowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Fund - R-1rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_C000063432Memberrr_ProspectusShareClassAxisexplicitMemberPrincipal LifeTime 2025 FundPrincipal LifeTime 2025 Fund - R-1iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue167167falsefalsefalsetruefalse2truefalsetrue517517falsefalsefalsetruefalse3truefalsetrue892892falsefalsefalsetruefalse4truefalsetrue19441944falsefalsefalsetruefalseOthernanafalsefalsePrincipal LifeTime 2025 Fund - 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R-4iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue116116falsefalsefalsetruefalse2truefalsetrue362362falsefalsefalsetruefalse3truefalsetrue628628falsefalsefalsetruefalse4truefalsetrue13861386falsefalsefalsetruefalseOthernanafalsefalsePrincipal LifeTime 2025 Fund - R-45falseRowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Fund - R-5rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_C000063433Memberrr_ProspectusShareClassAxisexplicitMemberPrincipal LifeTime 2025 FundPrincipal LifeTime 2025 Fund - R-5iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue104104falsefalsefalsetruefalse2truefalsetrue325325falsefalsefalsetruefalse3truefalsetrue563563falsefalsefalsetruefalse4truefalsetrue12481248falsefalsefalsetruefalseOthernanafalsefalsePrincipal LifeTime 2025 Fund - R-545Expense Example Principal LifeTime 2025 Fund (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExample.No authoritative reference available.falsefalseExpense Example, With Redemption [Table]14false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Portfolio Turnover falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 5 -Subsection instructions falsefalsePortfolio Turnover, Heading15false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>As a fund of funds, the Fund does not pay transaction costs, such as commissions, when it buys and sells shares of underlying funds (or "turns over" its portfolio). An underlying fund does pay transaction costs when it buys and sells portfolio securities, and a higher portfolio turnover may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the examples, affect the performance of the underlying fund and the Fund. During its most recent fiscal year, the Fund's portfolio turnover rate was 25.2% of the average value of its portfolio.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subsection example falsefalsePortfolio Turnover16false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Principal Investment StrategiesfalsefalsefalsefalsefalseOtherxbrli: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 falsefalseInvestment Strategy, Heading17false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The Fund operates as a "target date fund." It invests in underlying Principal Funds, Inc. ("PFI") domestic and foreign equity, real estate investments, and fixed-income Funds according to an asset allocation strategy designed for investors having an investment time horizon comparable to that of the Fund. The Fund's asset allocation will become more conservative over time as investment goals near (for example, retirement, which is assumed to begin at age 65) and investors become more risk-averse. The Fund invests in PFI Institutional Class shares of underlying funds. It is managed by Principal Management Corporation ("Principal"); Principal has hired a sub-advisor, Principal Global Investors, LLC ("PGI"), to assist in managing the Fund. Principal, with assistance from PGI, develops, implements and monitors the Fund's strategic or long-term asset class targets and target ranges, is also responsible for an active rebalancing strategy designed to identify asset classes that appear attractive over the short term and sets the percentage of Fund assets to be allocated to a particular asset class. Principal selects the underlying funds for each asset class and the target weights for each underlying fund. Principal, with assistance from PGI, may shift asset class targets in response to normal evaluative processes, the shortening time horizon of the Fund or changes in market forces or Fund circumstances. Principal may add, remove, or substitute underlying funds at any time. In selecting underlying funds and target weights, Principal considers both quantitative measures (e.g., past performance, expected levels of risk and returns, expense levels, diversification and style consistency) and qualitative factors (e.g., organizational stability, investment experience, investment and risk management processes, and information, trading, and compliance systems). There are no minimum or maximum percentages of assets that the Fund must invest in a specific asset class or underlying fund. Within 10 to 15 years after its target year, the Fund's underlying fund allocation is expected to match that of the Principal LifeTime Strategic Income Fund. At that time, the Fund may be combined with that fund if the Board of Directors determines that the combination is in the best interests of Fund shareholders. It is expected that at the target date in the Fund's name, the shareholder will begin gradually withdrawing the account's value. There is no guarantee that this Fund will provide adequate income at or through retirement.</pre>falsefalsefalsefalsefalseOtherus-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 falsefalseInvestment Strategy, Narrative18false0rr_RiskHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Principal RisksfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b falsefalseRisk, Heading19false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The broad diversification of the Fund is designed to cushion severe losses in any one investment sector and moderate overall price volatility. However, the Fund is subject to the particular risks of the underlying funds in the proportions in which the Fund invests in them, and its share prices will fluctuate as the prices of underlying fund shares rise or fall with changing market conditions. If you sell your shares when their value is less than the price you paid, you will lose money. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund (directly or indirectly through the underlying funds), in alphabetical order, are: Asset Allocation Risk. A fund's selection and weighting of asset classes and/or underlying funds may cause it to underperform other funds with a similar investment objective. Conflict of Interest Risk. The Advisor and its affiliates earn different fees from different underlying funds and may have an incentive to allocate more fund-of-fund assets to underlying funds from which they receive higher fees. Derivatives Risk. Transactions in derivatives (such as options, futures, and swaps) may increase volatility, cause the liquidation of portfolio positions when not advantageous to do so and produce disproportionate losses. Equity Securities Risk. Equity securities (common, convertible preferred stocks and other securities whose values are tied to the price of stocks, such as rights, warrants and convertible debt securities) could decline in value if the issuer's financial condition declines or in response to overall market and economic conditions. A fund's principal market segment(s), such as large cap, mid cap or small cap stocks, or growth or value stocks, may underperform other market segments or the equity markets as a whole. Investments in smaller companies and mid-size companies may involve greater risk and price volatility than investments in larger, more mature companies. Fixed-Income Securities Risk. Fixed-income securities are subject to interest rate risk and credit quality risk. The market value of fixed-income securities generally declines when interest rates rise, and an issuer of fixed-income securities could default on its payment obligations. Foreign Securities Risk. The risks of foreign securities include loss of value as a result of: political or economic instability; nationalization, expropriation or confiscatory taxation; changes in foreign exchange rates and foreign exchange restrictions; settlement delays; and limited government regulation (including less stringent reporting, accounting, and disclosure standards than are required of U.S. companies). Certain of these risks are greater for investments in emerging markets. Growth Stock Risk. Market prices of growth stocks are often more sensitive than other securities to earnings expectations. High Yield Securities Risk. High yield fixed-income securities (commonly referred to as "junk bonds") are subject to greater credit quality risk than higher rated fixed-income securities and should be considered speculative. Index Fund Investment Risk. More likely than not, the fund will not provide investment performance that matches the index performance due to the fees and expenses of the fund. Investment Company Securities Risk. Fund shareholders bear indirectly their proportionate share of the expenses of other investment companies in which the Fund invests. Portfolio Duration Risk. Portfolio duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund's average portfolio duration, the more sensitive the fund will be to changes in interest rates. Prepayment Risk. Unscheduled prepayments on mortgage-backed and asset-backed securities may have to be reinvested at lower rates. A reduction in prepayments may increase the effective maturities of these securities, exposing them to the risk of decline in market value over time (extension risk). Real Estate Investment Trusts ("REITs") Risk. A REIT could fail to qualify for tax-free pass-through of income under the Internal Revenue Code, and Fund shareholders will indirectly bear their proportionate share of the expenses of REITs in which the Fund invests. Real Estate Securities Risk. Real estate securities are subject to the risks associated with direct ownership of real estate, including declines in value, adverse economic conditions, increases in expenses, regulatory changes and environmental problems. Underlying Fund Risk. As of the date of this prospectus, this fund was being used as an underlying fund of a fund of funds, and 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. U.S. Government Securities Risk. Yields available from U.S. government securities are generally lower than yields from many other fixed-income securities. U.S. Government Sponsored Securities Risk. Securities issued by U.S. government-sponsored or -chartered enterprises such as the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association, and the Federal Home Loan Banks are not issued or guaranteed by the U.S. Treasury. Value Stock Risk. The market may not recognize the intrinsic value of value stocks for a long time, or they may be appropriately priced at the time of purchase.</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, Narrative20false0rr_BarChartAndPerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PerformancefalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalseBar Chart and Performance Table, Heading21false0rr_PerformanceNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The following information provides an indication of the risks of investing in the Fund. The bar chart shows the investment returns of the Fund's Class R-2 shares for each full calendar year of operations for 10 years (or, if shorter, the life of the Fund). The table shows, for each share class of the Fund and for the last one, five, and ten calendar year periods (or, if shorter, the life of the Fund), how the Fund's average annual total returns compare to the returns of one or more broad-based market indices. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. You may get updated performance information online at www.principal.com or by calling 1-800-547-7754. The Life of Fund results are measured from the date the R-1, R-2, R-3, R-4, and R-5 Class Shares were first sold (February 29, 2008). Performance of a blended index shows how the Fund's performance compares to an index with similar investment objectives. Performance of the components of the blended index are also shown. Effective March 31, 2010, the weightings for the Principal LifeTime 2025 Blended Index were 52.3% Russell 3000 Index, 20.2% MSCI-EAFE Index NDTR D, and 27.5% Barclays Capital Aggregate Bond Index. Effective March 31, 2011, the weightings for the Principal LifeTime 2025 Blended Index will be 53.25% Russell 3000 Index, 21.50% MSCI-EAFE Index NDTR D, and 25.25% Barclays Capital Aggregate Bond Index.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalsePerformance, Narrative22false0rr_BarChartNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The bar chart shows the investment returns of the Fund's Class R-2 shares for each full calendar year of operations for 10 years (or, if shorter, the life of the Fund).</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringProvide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalseBar Chart, Narrative23false0rr_BarChartHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Total Returns as of December 31 each year (Class R-2 shares) falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalseBar Chart, Heading24false0rr_BarChartTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.principal.com/role/BarChartData_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalseBarChart34.jpg<div style="display:none">~ http://www.principal.com/role/BarChartData_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://www.principal.com/role/BarChartData_S000022104Memberfalsefalse061203 - Schedule - Annual Total Returnstruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Fund - R-2rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_C000063430Memberrr_ProspectusShareClassAxisexplicitMemberPrincipal LifeTime 2025 FundPrincipal LifeTime 2025 Fund - R-2iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*11false0rr_AnnualReturn2009rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.25910.2591falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a -Subsection b falsefalseAnnual Return 20090rr_AnnualReturn2009truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.25910.2591falsefalsefalsetruefalseOthernanafalsefalseAnnual Return 20092falseRowprimaryElement*12false0rr_AnnualReturn2010rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.14190.1419falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 20100rr_AnnualReturn2010truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.14190.1419falsefalsefalsetruefalseOthernanafalsefalseAnnual Return 201012Annual Total Returns UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No authoritative reference available.falsefalseBar Chart [Table]25false0rr_BarChartClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>Highest return for a quarter during the period of the bar chart above: Q3 '09 15.34% Lowest return for a quarter during the period of the bar chart above: Q1 '09 -9.33% </pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseBar Chart, Closing26false0rr_PerformanceTableNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class R-1 shares only and would be different for Class R-2, R-3, R-4 and R-5 shares.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a table showing the Fund's (A) average annual total return; (B) average annual total return (after taxes on distributions); and (C) average annual total return (after taxes on distributions and redemption). A Money Market Fund should show only the returns described in clause (A) of the preceding sentence. All returns should be shown for 1-, 5-, and 10- calendar year periods ending on the date of the most recently completed calendar year (or for the life of the Fund, if shorter), but only for periods subsequent to the effective date of the Fund's registration statement. The table also shouldshow the returns of an appropriate broadbased securities market index as defined in Instruction 5 to Item 22(b)(7) for the same periods. A Fund that has been in existence for more than 10 years also may include returns for the life of the Fund. A Money Market Fund may provide the Fund's 7-day yield ending on the date of the most recent calendar year or disclose a toll-free (or collect) telephone number that investors can use to obtain the Fund's current 7-day yield. For a Fund (other than a Money Market Fund or a Fund described in General Instruction C.3.(d)(iii)), provide the information in the following table with the specified captions AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, _____). For a Fund that provides annual total returns for only one calendar year or for a Fund that does not include the bar chart because it does not have annual returns for a full calendar year, modify, as appropriate, the narrative explanation required by paragraph (c)(2)(i) (e.g., by stating that the information gives some indication of the risks of an investment in the Fund by comparing the Fund's performance with a broad measure of market performance).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iv -Subsection b falsefalsePerformance Table, Narrative27false0rr_AverageAnnualReturnCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Average Annual Total Returns For the periods ended December 31, 2010falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 5 -Subsection b falsefalseAverage Annual Returns, Caption28false0rr_PerformanceTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.principal.com/role/PerformanceTableData_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div>falsefalse<div style="display:none">~ http://www.principal.com/role/PerformanceTableData_S000022104Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div>truehttp://www.principal.com/role/PerformanceTableData_S000022104Memberfalsefalse061204 - Schedule - Average Annual Total Returns {Transposed}truefalsefalse1falseColumnprimaryElement*3false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Class R-1 Return Before Taxesfalsefalsefalsetruefalse2falsetruefalse00Class R-1 Return After Taxes on Distributionsfalsefalsefalsetruefalse3falsetruefalse00Class R-1 Return After Taxes on Distribution and Sale of Fund Sharesfalsefalsefalsetruefalse4falsetruefalse00Class R-2 Return Before Taxesfalsefalsefalsetruefalse5falsetruefalse00Class R-3 Return Before Taxesfalsefalsefalsetruefalse6falsetruefalse00Class R-4 Return Before Taxesfalsefalsefalsetruefalse7falsetruefalse00Class R-5 Return Before Taxesfalsefalsefalsetruefalse8falsetruefalse00MSCI -EAFE Index NDTR D (reflects no deduction for fees, expenses, or taxes)falsefalsefalsetruefalse9falsetruefalse00Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)falsefalsefalsetruefalse10falsetruefalse00Barclays Capital Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)falsefalsefalsetruefalse11falsetruefalse00Principal LifeTime 2025 Blended Index (reflects no deduction for fees, expenses, or taxes)falsefalsefalsetruefalseOtherxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, LabelfalseUSDfalsefalse$2falseColumnprimaryElement*4false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.14070.1407falsefalsefalsetruefalse2truetruetrue0.13310.1331falsefalsefalsetruefalse3truetruetrue0.09480.0948falsefalsefalsetruefalse4truetruetrue0.14190.1419falsefalsefalsetruefalse5truetruetrue0.14510.1451falsefalsefalsetruefalse6truetruetrue0.14590.1459falsefalsefalsetruefalse7truetruetrue0.14800.1480falsefalsefalsetruefalse8truetruetrue0.07750.0775falsefalsefalsetruefalse9truetruetrue0.16930.1693falsefalsefalsetruefalse10truetruetrue0.06540.0654falsefalsefalsetruefalse11truetruetrue0.12730.1273falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, 1 YearfalseUSDfalsefalse$3falseColumnprimaryElement*7false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00090.0009falsefalsefalsetruefalse2truetruetrue-0.0045-0.0045falsefalsefalsetruefalse3truetruetrue-0.0017-0.0017falsefalsefalsetruefalse4truetruetrue0.00210.0021falsefalsefalsetruefalse5truetruetrue0.00350.0035falsefalsefalsetruefalse6truetruetrue0.00570.0057falsefalsefalsetruefalse7truetruetrue0.00690.0069falsefalsefalsetruefalse8truetruetrue-0.0466-0.0466falsefalsefalsetruefalse9truetruetrue0.01170.0117falsefalsefalsetruefalse10truetruetrue0.05580.0558falsefalsefalsetruefalse11truetruetrue0.01470.0147falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Since InceptionfalseUSDfalsefalse$4falseColumnprimaryElement*8false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002008-02-29falsefalsetruetruefalse2falsetruefalse002008-02-29falsefalsetruetruefalse3falsetruefalse002008-02-29falsefalsetruetruefalse4falsetruefalse002008-02-29falsefalsetruetruefalse5falsetruefalse002008-02-29falsefalsetruetruefalse6falsetruefalse002008-02-29falsefalsetruetruefalse7falsetruefalse002008-02-29falsefalsetruetruefalse8falsetruefalse002008-02-29falsefalsetruetruefalse9falsetruefalse002008-02-29falsefalsetruetruefalse10falsetruefalse002008-02-29falsefalsetruetruefalse11falsetruefalse002008-02-29falsefalsetruetruefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception DatefalseUSDfalsefalse$1falseRowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-03-01T00:00:002011-03-01T00:00:00falsefalsePrincipal LifeTime 2025 Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000898745_S000022104Memberdei_LegalEntityAxisexplicitMemberfalsefalsePrincipal LifeTime 2025 Fund - 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