Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 13, 2012
Small-MidCap Dividend Income Fund (Prospectus Summary) | Small-MidCap Dividend Income Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Small-MidCap Dividend Income Fund
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Fund primarily seeks to provide a relatively high level of current income and long-term growth of income
Investment Objective, Secondary	rr_ObjectiveSecondaryTextBlock	and secondarily long-term growth of capital, while investing primarily in small- to mid-capitalization companies.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. Information about discounts is available from your financial professional and in "Choosing a Share Class and The Costs of Investing" beginning on page 38 of the Fund's prospectus and "Multiple Class Structure" beginning on page 59 of the Fund's Statement of Additional Information.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. From June 6, 2011, date operations commenced, through August 31, 2011, the Fund's annualized portfolio turnover rate was 43.5% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	43.50%
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses estimated for the year ending August 31, 2012.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	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:
Expense Example, No Redemption, By Year, Caption	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets, plus borrowings for investment purposes, in dividend-paying equity securities of companies with small to medium market capitalizations (those with market capitalizations ranging from between $200 million and $7 billion) at the time of purchase. The Fund invests in value equity securities, an investment strategy that emphasizes buying equity securities that appear to be undervalued. The Fund will invest in the securities of foreign issuers, real estate investment trusts, preferred securities, convertible securities, fixed-income securities, master limited partnerships, and royalty trusts.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Fund may be an appropriate investment for investors who seek dividends to generate income or to reinvest for growth and who can accept fluctuations in the value of investments and the risks of investing in real estate investment trust securities and foreign securities.    The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. 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, in alphabetical order, are:    Convertible Securities Risk. Convertible securities can be bonds, notes, debentures, preferred stock or other securities which are convertible into common stock. Convertible securities are subject to both the credit and interest rate risks associated with fixed income securities and to the stock market risk associated with equity securities.    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).    Master Limited Partnership ("MLP") Risk. MLPs are publicly-traded limited partnership interests or units. An MLP that invests in a particular industry (e.g., oil and gas) will be harmed by detrimental economic events within that industry. As partnerships, MLPs may be subject to less regulation (and less protection for investors) under state laws than corporations. In addition, MLPs may be subject to state taxation in certain jurisdictions, which may reduce the amount of income an MLP pays to its investors.    Preferred Securities Risk. Preferred securities are junior subordinated securities in a company's capital structure and therefore can be subject to greater credit and liquidation risk. An issuer of preferred securities could redeem the security prior to the stated maturity date and reduce the return of the security.    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. Risk of Being an Underlying 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.    Royalty Trust Risk. A royalty trust generally acquires an interest in natural resource or chemical companies and distributes the income it receives to its investors. A sustained decline in demand for natural resource and related products could adversely affect royalty trust revenues and cash flows. Such a decline could result from a recession or other adverse economic conditions, an increase in the market price of the underlying commodity, higher taxes or other regulatory actions that increase costs, or a shift in consumer demand. Rising interest rates could adversely affect the performance, and limit the capital appreciation, of royalty trusts because of the increased availability of alternative investments at more competitive yields. Fund shareholders will indirectly bear their proportionate share of the royalty trusts' expenses.    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.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	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.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	No performance information is shown because the Fund has not yet had a calendar year of performance. The Fund's performance will be benchmarked against the Russell 2500 Value Index.
Performance, One Year or Less	rr_PerformanceOneYearOrLess	No performance information is shown because the Fund has not yet had a calendar year of performance.
Small-MidCap Dividend Income Fund (Prospectus Summary) | Small-MidCap Dividend Income Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of dollars subject to charge)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.39%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.19%
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2]
Total Annual Fund Operating Expenses after Expense Reimbursement	rr_NetExpensesOverAssets	2.15%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-12-31
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	318
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	681
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	218
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	681

[1] Other Expenses estimated for the year ending August 31, 2012.

[2] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund's expenses attributable to Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense through the period ending December 31, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 2.15% for Class C shares. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.