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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading
American Beacon Stephens Mid-Cap Growth FundSM
Objective [Heading] rr_ObjectiveHeading
Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks long-term growth of capital.
Expense [Heading] rr_ExpenseHeading
Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
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 discounts if you and your eligible family members invest, or agree to invest in the future, at least $50,000 in the A Class shares of the American Beacon Funds. More information about these and other discounts is available from your financial professional and in “Choosing Your Share Class” on page 31 of the Prospectus and “Additional Purchase and Sale Information for A Class Shares” on page 35 of the statement of additional information.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 2014-04-30
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading

Portfolio Turnover
Portfolio Turnover [Text Block] 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. During the most recent fiscal year, the Fund’s portfolio turnover rate was 27% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 27.00%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts
You may qualify for sales discounts if you and your eligible family members invest, or agree to invest in the future, at least $50,000 in the A Class shares of the American Beacon Funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expense Example [Heading] rr_ExpenseExampleHeading

Example.
Expense Example Narrative [Text Block] 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 [Text] rr_ExpenseExampleNoRedemptionByYearCaption
Assuming no redemption of shares:
Strategy [Heading] rr_StrategyHeading
Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of medium capitalization companies. The Fund considers a company to be a medium capitalization company if it has a market capitalization, at the time of investment, between $1 billion and the market capitalization of the largest company in the Russell Midcap® Index, which was $25.0 billion as of December 31, 2012.

Most of the assets of the Fund are invested in U.S. common stocks Stephens Investment Management Group, LLC (“SIMG”) believes have clear indicators of future earnings growth, or that demonstrate other potential for growth of capital. The Fund may invest in other securities, including preferred stock, securities convertible into common stock, U.S dollar denominated foreign stock traded on U.S. exchanges, American Depositary Receipts (“ADRs”) and real estate investment trusts (“REITs”). In selecting companies for the Fund, SIMG employs quantitative analysis and fundamental research with a focus on earnings growth. SIMG will sell a security when appropriate and consistent with the Fund’s investment objectives and policies.

The Fund may also invest cash balances in other investment companies, including money market funds.
Risk [Heading] rr_RiskHeading
Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

There is no assurance that the Fund will achieve its investment objective and you could lose part or all of your investment in the Fund. The Fund is not designed for investors who need an assured level of income and is intended to be a long-term investment. The Fund is not a complete investment program and may not be appropriate for all investors. Investors should carefully consider their own investment goals and risk tolerance before investing in the Fund. The principal risks of investing in the Fund are:

 

Equity Investments Risk

 

Equity securities generally are subject to market risk. The Fund’s investments in equity securities may include common stocks, preferred stocks, securities convertible into common stocks, U.S. dollar-denominated foreign stocks traded on U.S. exchanges, REITs, and ADRs. Investing in such securities may expose the Fund to additional risks.

 

Common stock generally is subordinate to preferred stock upon the liquidation or bankruptcy of the issuing company. Preferred stocks and convertible securities are sensitive to movements in interest rates. In addition, convertible securities are subject to the risk that the credit standing of the issuer may have an effect on the convertible securities’ investment value. Investments in ADRs are subject to certain of the risks associated with investing directly in foreign securities. Investments in REITs are subject to the risks associated with investing in the real estate industry such as adverse developments affecting the real estate industry and real property values.

 

Foreign Exposure Risk

 

The Fund may invest in securities issued by foreign companies through ADRs and U.S. dollar-denominated foreign stocks trading on U.S. exchanges. These securities are subject to many of the risks inherent in investing in foreign securities, including, but not limited to, currency fluctuations and political and financial instability in the home country of a particular ADR or foreign stock. Non-U.S. investments carry potential risks not associated with U.S. investments. Such risks include, but are not limited to: (1) currency exchange rate fluctuations, (2) political and financial instability, (3) less liquidity and greater volatility, (4) lack of uniform accounting, auditing and financial reporting standards, (5) increased price volatility, and (6) less government regulation and supervision of foreign stock exchanges, brokers and listed companies.

Growth Companies Risk

 

Growth companies are expected to increase their earnings at a certain rate. When these expectations are not met, the prices of these stocks may go down, even if earnings showed an absolute increase. Growth company stocks also typically lack the dividend yield that can cushion stock prices in market downturns. Different investment styles tend to shift in and out of favor, depending on market conditions and investor sentiment. The Fund’s growth style could cause the Fund to underperform funds that use a value or non-growth approach to investing or have a broader investment style.

 

Investment Risk

 

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. When you sell your shares of the Fund, they could be worth less than what you paid for them. Therefore, you may lose money by investing in the Fund.

 

Issuer Risk

 

The value of a security may decline for a number of reasons which directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods or services, as well as the historical and prospective earnings of the issuer and the value of its assets.

 

Market Events Risk

 

Turbulence in financial markets and reduced liquidity in equity, credit and fixed-income markets may negatively affect many issuers worldwide which could adversely affect the Fund.

 

Market Risk

 

Market risks, including political, regulatory, market and economic developments, and developments that impact specific economic sectors, industries or segments of the market, can affect the value of the Fund’s shares. The Fund’s equity investments are subject to stock market risk, which involves the possibility that the value of the Fund’s investments in stocks will decline due to drops in the stock market. From time to time, certain investments held by the Fund may have limited marketability and may be difficult to sell at favorable times or prices. If the Fund is forced to sell such holdings to meet redemption requests or other cash needs, the Fund may have to sell them at a loss.

 

Mid-Capitalization Companies Risk

 

Investing in the securities of mid-capitalization companies involves greater risk and the possibility of greater price volatility than investing in larger capitalization companies. Since mid-capitalization companies may have limited operating history, product lines and financial resources, the securities of these companies may lack sufficient market liquidity and can be sensitive to expected changes in interest rates, borrowing costs and earnings.

 

Other Investment Companies Risk

 

The Fund may invest in shares of other registered investment companies, including money market funds. To the extent that the Fund invests in shares of other registered investment companies, you will indirectly bear fees and expenses charged by the underlying funds in addition to the Fund’s direct fees and expenses and will be subject to the risks associated with investments in those funds.

 

Securities Selection Risk

 

Securities selected by the sub-advisor or the Manager for the Fund may not perform to expectations. This could result in the Fund’s underperformance compared to other funds with similar investment objectives.
Risk Lose Money [Text] rr_RiskLoseMoney
There is no assurance that the Fund will achieve its investment objective and you could lose part or all of your investment in the Fund.
Risk Not Insured Depository Institution [Text] 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
Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The bar chart and table below provide an indication of risk by showing how the Fund’s performance has varied from year to year. The table shows how the Fund’s performance compares to the Russell Midcap® Growth Index, which is the Fund’s primary benchmark and is a broad measure of market performance. In addition, the Fund’s performance is compared to the S&P 500®Index, which is the Fund’s secondary index and is provided to offer a broader market perspective.

 

The Investor Class and Institutional Class shares of the Fund have adopted the performance history and financial statements of the Class A and Class I shares, respectively, of the Fund’s predecessor. The performance of the Fund’s Investor Class shares shown in the chart and table below represents the returns achieved by the Class A shares of the Fund’s predecessor from February 1, 2006 to February 24, 2012, and the performance of the Investor Class from February 24, 2012 through December 31, 2012. The table below also shows the performance of the A Class, C Class, Y Class and Institutional Class shares of the Fund. The performance shown for the Institutional Class shares of the Fund represents: (1) the returns achieved by the Class A Shares of the Fund’s predecessor from February 1, 2006 to August 31, 2006, the inception date of the predecessor Fund’s Class I shares; (2) the performance of the Class I shares from inception to February 24, 2012; and (3) the performance of the Institutional Class shares from February 24, 2012 through December 31, 2012. Returns shown for the Fund’s Y Class, A Class and C Class shares represent the returns achieved by the Class A shares of the Fund’s predecessor from February 1, 2006 to February 24, 2012, and the performance of the Y Class, A Class and C Class shares, respectively, from February 24, 2012 through December 31, 2012. In each case, the newer share classes would have had similar annual returns to the predecessor Fund’s Class A and Class I shares because the shares of each class represent investments in the same portfolio securities. However, because the Class A shares of the predecessor Fund had higher expenses than the Fund’s Institutional Class and Y Class shares now have, the total returns were lower than the Institutional Class and Y Class shares would have realized had the Y Class shares been in existence since February 1, 2006. Since the Investor Class shares had lower expenses than the Fund’s A Class and C Class shares now have, its performance was better than the performance of the A Class and C Class shares would have realized in the same period. The performance of the Fund and the Fund’s predecessor shown in the bar chart below do not include sales charges. If sales charges were reflected, returns would be lower. You may obtain updated performance information on the Fund’s website at www.americanbeaconfunds.com. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns
The bar chart and table below provide an indication of risk by showing how the Fund’s performance has varied from year to year.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress

www.americanbeaconfunds.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture
Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Investor Class shares Year-By-Year Percentage Returns as of 12/31 of Each Year
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads
The performance of the Fund and the Fund’s predecessor shown in the bar chart below do not include sales charges. If sales charges were reflected, returns would be lower.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Highest Quarterly Return:
(2/1/06 through 12/31/12)

 

16.31%
(3rd Quarter 2009)

Lowest Quarterly Return:
(2/1/06 through 12/31/12)

 

-28.39%
(4th Quarter 2008)
Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns For the periods ended December 31, 2012
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads
The performance of the Fund and the Fund’s predecessor shown in the bar chart below do not include sales charges. If sales charges were reflected, returns would be lower.
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes IndexNoDeductionForFeesExpensesTaxes
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate

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.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred

If you hold your Fund shares through a tax-deferred arrangement, such as an individual retirement account or a 401(k), the after-tax returns do not apply to your situation.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Investor Class shares; after-tax returns for other share classes will vary. 
Investor Class
  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge load (as a percentage of the lower of original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none
Management fees rr_ManagementFeesOverAssets 0.59%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 1.08% [1]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total annual fund operating expenses rr_ExpensesOverAssets 1.68%
Expense reduction and reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.30%)
Total annual fund operating expenses after expense reduction and reimbursement rr_NetExpensesOverAssets 1.38% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 141
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 501
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 885
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,962
Annual Return 2007 rr_AnnualReturn2007 24.44%
Annual Return 2008 rr_AnnualReturn2008 (45.89%)
Annual Return 2009 rr_AnnualReturn2009 39.94%
Annual Return 2010 rr_AnnualReturn2010 27.89%
Annual Return 2011 rr_AnnualReturn2011 2.45%
Annual Return 2012 rr_AnnualReturn2012 14.75%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel
Highest Quarterly Return:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 16.31%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel
Lowest Quarterly Return:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (28.39%)
1 Year rr_AverageAnnualReturnYear01 14.75% [3]
5 Years rr_AverageAnnualReturnYear05 2.71% [3]
Since Inception rr_AverageAnnualReturnSinceInception 4.89% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 01, 2006 [3]
A Class
  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum deferred sales charge load (as a percentage of the lower of original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none
Management fees rr_ManagementFeesOverAssets 0.59%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.99% [1]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total annual fund operating expenses rr_ExpensesOverAssets 1.84%
Expense reduction and reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.34%)
Total annual fund operating expenses after expense reduction and reimbursement rr_NetExpensesOverAssets 1.50% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 719
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 1,089
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,483
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,583
1 Year rr_AverageAnnualReturnYear01 8.15% [3]
5 Years rr_AverageAnnualReturnYear05 1.50% [3]
Since Inception rr_AverageAnnualReturnSinceInception 3.99% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 24, 2012 [3]
C Class
  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge load (as a percentage of the lower of original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther 1.00%
Management fees rr_ManagementFeesOverAssets 0.59%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other expenses rr_OtherExpensesOverAssets 12.95% [1]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total annual fund operating expenses rr_ExpensesOverAssets 14.55%
Expense reduction and reimbursement rr_FeeWaiverOrReimbursementOverAssets (12.30%)
Total annual fund operating expenses after expense reduction and reimbursement rr_NetExpensesOverAssets 2.25% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 328
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 2,940
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 5,158
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 9,096
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 228
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 2,940
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 5,158
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 9,096
1 Year rr_AverageAnnualReturnYear01 13.26% [3]
5 Years rr_AverageAnnualReturnYear05 2.62% [3]
Since Inception rr_AverageAnnualReturnSinceInception 4.82% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 24, 2012 [3]
Y Class
  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge load (as a percentage of the lower of original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none
Management fees rr_ManagementFeesOverAssets 0.59%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 3.26% [1]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total annual fund operating expenses rr_ExpensesOverAssets 3.86%
Expense reduction and reimbursement rr_FeeWaiverOrReimbursementOverAssets (2.76%)
Total annual fund operating expenses after expense reduction and reimbursement rr_NetExpensesOverAssets 1.10% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 923
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,753
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 3,913
1 Year rr_AverageAnnualReturnYear01 15.26% [3]
5 Years rr_AverageAnnualReturnYear05 2.80% [3]
Since Inception rr_AverageAnnualReturnSinceInception 4.96% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 24, 2012 [3]
Institutional Class
  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge load (as a percentage of the lower of original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none
Management fees rr_ManagementFeesOverAssets 0.59%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.69% [1]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total annual fund operating expenses rr_ExpensesOverAssets 1.29%
Expense reduction and reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.29%)
Total annual fund operating expenses after expense reduction and reimbursement rr_NetExpensesOverAssets 1.00% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 102
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 381
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 680
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,531
1 Year rr_AverageAnnualReturnYear01 15.19% [3]
5 Years rr_AverageAnnualReturnYear05 2.99% [3]
Since Inception rr_AverageAnnualReturnSinceInception 7.12% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2006 [3]
After Taxes on Distributions | Investor Class
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 14.65% [3]
5 Years rr_AverageAnnualReturnYear05 2.69% [3]
Since Inception rr_AverageAnnualReturnSinceInception 4.88% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 01, 2006 [3]
After Taxes on Distributions and Sales | Investor Class
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 9.72% [3]
5 Years rr_AverageAnnualReturnYear05 2.32% [3]
Since Inception rr_AverageAnnualReturnSinceInception 4.24% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 01, 2006 [3]
Russell Mid-Cap® Growth Index
  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel
(reflects no deduction for fees, expenses or taxes)
 [3]
1 Year rr_AverageAnnualReturnYear01 15.81% [3]
5 Years rr_AverageAnnualReturnYear05 3.23% [3]
Since Inception rr_AverageAnnualReturnSinceInception 4.59% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 01, 2006 [3]
Lipper Mid-Cap Growth Funds Index
  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel
(reflects no deduction for fees, expenses or taxes)
 [3]
1 Year rr_AverageAnnualReturnYear01 13.37% [3]
5 Years rr_AverageAnnualReturnYear05 1.49% [3]
Since Inception rr_AverageAnnualReturnSinceInception 4.53% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 01, 2006 [3]
S&P 500 Index
  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel
(reflects no deduction for fees, expenses or taxes)
 [3]
1 Year rr_AverageAnnualReturnYear01 16.00% [3]
5 Years rr_AverageAnnualReturnYear05 1.66% [3]
Since Inception rr_AverageAnnualReturnSinceInception 3.78% [3]
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 01, 2006 [3]
[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets provided in the Fund's Financial Highlights table, which reflects the operating expenses of the Fund and does not include Acquired Fund Fees and Expenses.
[2] The Manager has contractually agreed to reduce and/or reimburse the A Class, C Class, Y Class, Institutional Class, and Investor Class of the Fund for Other Expenses through April 30, 2014 to the extent that Total Annual Fund Operating Expenses for the Fund exceed 1.49%, 2.24%, 1.99%, 0.09% and 1.37% for the A Class, C Class, Y Class, Institutional Class, and Investor Class, respectively (excluding taxes, brokerage commissions, acquired fund fees and expenses and other extraordinary expenses such as litigation). The contractual expense arrangement can be changed by approval of a majority of the Fund's Board of Trustees. The Manager can be reimbursed by the Fund for any contractual or voluntary fee reductions or expense reimbursements if reimbursement to the Manager (a) occurs within three years after the Manager's own reduction or reimbursement and (b) does not cause the Total Annual Fund Operating Expenses of a class to exceed the percentage limit contractually agreed.
[3] After-tax returns are shown only for Investor Class shares; after-tax returns for other share classes will vary. 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. If you hold your Fund shares through a tax-deferred arrangement, such as an individual retirement account or a 401(k), the after-tax returns do not apply to your situation.