This table describes the fees and expenses that you may pay if you buy and hold shares 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 $50,000 in Class A shares of Principal Funds, Inc. More information about these and other discounts is available from your financial professional and in “Choosing a Share Class and The Costs of Investing” beginning on page 24 of the Fund’s prospectus and “Multiple Class Structure” beginning on page 53 of the Fund’s Statement of Additional Information.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment):

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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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. This is a new Fund and does not yet have a portfolio turnover rate to

disclose.

Expense Breakpoint Discounts [Text]

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You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Class A shares of Principal Funds, Inc.

Expense Breakpoint, Minimum Investment Required [Amount]

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$ 50,000

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

Expense Example by, Year, Caption [Text]

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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 [Text]

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You would pay the following expenses if you did not redeem your shares:

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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Under normal circumstances, the Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities of companies with small market capitalizations at the time of each purchase. For this Fund, companies with small market capitalizations are those with market capitalizations within the range of companies comprising the MSCI World ex-USA Small Cap Index (as of December 31, 2013, this range was between approximately $69 million and $8.4 billion). The Fund invests primarily in foreign equity securities. The Fund has no limitation on the percentage of assets that is invested in any one country or denominated in any one currency, but the Fund typically invests in foreign securities of more than 10 countries. Primary consideration is given to securities of corporations of developed areas, such as Japan, Western Europe, Canada, Australia, and New Zealand. The Fund actively trades securities.

Risk [Heading]

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Principal Risks

Risk Narrative [Text Block]

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The Fund may be an investment for investors seeking long-term growth of capital in markets outside of the U.S., who are able to assume the increased risks of higher price volatility and currency fluctuations associated with investments in international equity securities which trade in non-U.S. currencies.

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:

Active Trading Risk. A fund that has a portfolio turnover rate over 100% is considered actively traded. Actively trading portfolio securities may accelerate realization of taxable gains and losses, lower fund performance and may result in high portfolio turnover rates and increased brokerage costs.

Currency Risk. Risks of investing in securities denominated in, or that trade in, foreign (non-U.S.) currencies include changes in foreign exchange rates and foreign exchange restrictions.

Equity Securities Risk. The value of equity securities could decline 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.

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; settlement delays; and limited government regulation (including less stringent reporting, accounting, and disclosure standards than are required of U.S. companies).

Risk Lose Money [Text]

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Many factors affect that value, and it is possible to lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

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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]

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Performance

Performance Narrative [Text Block]

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No performance information is shown below because the Fund has not yet had a calendar year of performance. The Fund’s performance is benchmarked against the MSCI World ex-USA Small Cap Index. Performance information provides an indication of the risks of investing in the Fund. 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.principalfunds.com or by calling 1-800-222-5852.

Performance One Year or Less [Text]

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No performance information is shown below because the Fund has not yet had a calendar year of performance.

Performance Availability Phone [Text]

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1-800-222-5852

Performance Availability Website Address [Text]

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www.principalfunds.com

Performance Past Does Not Indicate Future [Text]

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Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

PFI Prospectus - Class A,P | International Small Company Fund | International Small Company Fund, Class A

Risk/Return:

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Trading Symbol

dei_TradingSymbol

PICAX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

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5.50%

Maximum Deferred Sales Charge (as a percentage)

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1.00%

Management Fees (as a percentage of Assets)

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1.05%

Distribution and Service (12b-1) Fees

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0.25%

Other Expenses (as a percentage of Assets):

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0.61%

^[1]

Expenses (as a percentage of Assets)

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1.91%

Fee Waiver or Reimbursement

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(0.31%)

^[2]

Net Expenses (as a percentage of Assets)

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1.60%

Fee Waiver or Reimbursement over Assets, Date of Termination

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December 29, 2015

Expense Example, with Redemption, 1 Year

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704

Expense Example, with Redemption, 3 Years

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1,089

Expense Example, No Redemption, 1 Year

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704

Expense Example, No Redemption, 3 Years

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1,089

PFI Prospectus - Class A,P | International Small Company Fund | International Small Company Fund, Class P

Risk/Return:

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Trading Symbol

dei_TradingSymbol

PCOPX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

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none

Maximum Deferred Sales Charge (as a percentage)

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none

Management Fees (as a percentage of Assets)

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1.05%

Other Expenses (as a percentage of Assets):

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0.50%

^[1]

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

1.55%

Fee Waiver or Reimbursement

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(0.30%)

^[2]

Net Expenses (as a percentage of Assets)

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1.25%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

December 29, 2015

Expense Example, with Redemption, 1 Year

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127

Expense Example, with Redemption, 3 Years

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460

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

127

Expense Example, No Redemption, 3 Years

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$ 460

[1]

Based on estimated amounts for the current fiscal year.

[2]

Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund’s expenses by paying, if necessary, expenses normally payable by the Fund, (excluding interest expense, expenses related to fund investments, acquired fund fees and expenses, and other extraordinary expenses) to maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 1.60% for Class A shares. In addition, for Class P, the expense limit will maintain "Other Expenses" (expressed as a percent of average net assets on an annualized basis) not to exceed 0.20%, (excluding interest expense, expenses related to fund investments, acquired fund fees and expenses, and other extraordinary expenses). It is expected that the expense limit will continue through the period ending December 29, 2015; 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.