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Buffalo Mid Cap Discovery Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO MID CAP DISCOVERY FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the Buffalo Mid Cap Discovery Fund (“Mid Cap Discovery Fund” or the “Fund”) (formerly known as “Buffalo Discovery Fund”) is 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 42% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 42.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Mid Cap Discovery Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “mid-cap discovery companies.” Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), defines mid-cap discovery companies as companies, at the time of purchase, with market capitalizations within the range of the Russell Midcap® Growth Index, and are companies engaged in the pursuit and practical application of knowledge to discover, develop, and commercialize products, services, or intellectual property. As of June 30, 2024, the range of market capitalizations of the Russell Midcap® Growth Index was $658 million to $61.6 billion. In addition to the Fund’s investments in domestic securities, the Fund may invest up to 20% of its net assets in
sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.
Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. Currently, the Fund has significant investments in the information technology sector. The Fund may have significant investments in the healthcare sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Mid Cap Discovery Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “mid-cap discovery companies.”
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Mid Cap Discovery Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Mid Cap Discovery Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 0.38%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 23.84%
Worst Quarter: June 30, 2022 = -21.37%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Russell 3000® Index has replaced the Russell Midcap® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Mid Cap Discovery Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Mid Cap Discovery Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Mid Cap Discovery Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Mid Cap Discovery Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Mid Cap Discovery Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Mid Cap Discovery Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Mid Cap Discovery Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Mid Cap Discovery Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Mid Cap Discovery Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Mid Cap Discovery Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Mid Cap Discovery Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.

Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.

Healthcare Sector Risk. To the extent the Fund invests a significant portion of its assets in the healthcare sector, the Fund will be sensitive to changes in, and its performance will depend to a greater extent on, the overall condition of the healthcare sector. Companies in the healthcare sector are subject to extensive government regulation and their profitability can be significantly affected by regulatory changes. Other risk factors include rising costs of medical products and services, pricing pressure and limited product lines, loss or impairment of intellectual property rights and litigation regarding product or service liability.
Buffalo Mid Cap Discovery Fund | Sector Risk, Health Care Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Healthcare Sector Risk. To the extent the Fund invests a significant portion of its assets in the healthcare sector, the Fund will be sensitive to changes in, and its performance will depend to a greater extent on, the overall condition of the healthcare sector. Companies in the healthcare sector are subject to extensive government regulation and their profitability can be significantly affected by regulatory changes. Other risk factors include rising costs of medical products and services, pricing pressure and limited product lines, loss or impairment of intellectual property rights and litigation regarding product or service liability.
Buffalo Mid Cap Discovery Fund | Sector Risk, Information Technology Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Mid Cap Discovery Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo Mid Cap Discovery Fund | Large-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Large-Cap Company Risk – Larger, more established companies may be unable to respond quickly to new competitive challenges and are sometimes unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.
Buffalo Mid Cap Discovery Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Mid Cap Discovery Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Mid Cap Discovery Fund | Small-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Small-Cap Company Risk – Investing in small-cap companies may involve greater risk than investing in large- or mid-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than mid- and large-cap companies. In addition, small-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Mid Cap Discovery Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Mid Cap Discovery Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less
information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Mid Cap Discovery Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less
information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Mid Cap Discovery Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Mid Cap Discovery Fund | Russell Midcap® Growth Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell Midcap® Growth Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.87%
5 Years rr_AverageAnnualReturnYear05 13.81%
10 Years rr_AverageAnnualReturnYear10 10.57%
Buffalo Mid Cap Discovery Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index*(reflects no deduction for fees, expenses or taxes) [1]
1 Year rr_AverageAnnualReturnYear01 25.96% [1]
5 Years rr_AverageAnnualReturnYear05 15.16% [1]
10 Years rr_AverageAnnualReturnYear10 11.48% [1]
Buffalo Mid Cap Discovery Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFTX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.15%
Other Expenses rr_Component2OtherExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.01% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 103
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 322
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 558
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,236
Annual Return 2014 rr_AnnualReturn2014 10.68%
Annual Return 2015 rr_AnnualReturn2015 5.64%
Annual Return 2016 rr_AnnualReturn2016 5.56%
Annual Return 2017 rr_AnnualReturn2017 25.44%
Annual Return 2018 rr_AnnualReturn2018 (6.54%)
Annual Return 2019 rr_AnnualReturn2019 31.63%
Annual Return 2020 rr_AnnualReturn2020 33.81%
Annual Return 2021 rr_AnnualReturn2021 11.90%
Annual Return 2022 rr_AnnualReturn2022 (28.67%)
Annual Return 2023 rr_AnnualReturn2023 24.30%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 0.38%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 23.84%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.37%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 24.30%
5 Years rr_AverageAnnualReturnYear05 11.81%
10 Years rr_AverageAnnualReturnYear10 9.72%
Buffalo Mid Cap Discovery Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 24.30%
5 Years rr_AverageAnnualReturnYear05 9.24%
10 Years rr_AverageAnnualReturnYear10 7.59%
Buffalo Mid Cap Discovery Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 14.39%
5 Years rr_AverageAnnualReturnYear05 8.87%
10 Years rr_AverageAnnualReturnYear10 7.32%
Buffalo Mid Cap Discovery Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUITX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 482
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,073
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 24.50%
5 Years rr_AverageAnnualReturnYear05 11.98%
10 Years rr_AverageAnnualReturnYear10 9.89%
Buffalo Growth & Income Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO GROWTH & INCOME FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The investment objective of the Buffalo Growth & Income Fund (the “Growth & Income Fund” or the “Fund”) (formerly known as “Buffalo Dividend Focus Fund”) is current income,
Objective, Secondary [Text Block] rr_ObjectiveSecondaryTextBlock with long-term growth of capital as a secondary objective.
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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 4% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 4.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Growth & Income Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in a mix of growth equity securities and income producing securities, with no minimum or maximum investment requirements specified for either category. Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), defines growth equity securities as common stocks, preferred stocks, convertible securities, warrants, and rights of companies that, at the time of purchase, are constituents of the Russell 3000® Growth Index or exhibit growth characteristics (generates positive cash flows or earnings that increase at faster rates than the overall economy) consistent with inclusion of companies in the Russell 3000® Growth Index. KCM defines income producing securities as securities that pay interest or a dividend at least annually, such as convertible securities and dividend-paying equity securities (i.e., securities of companies that have historically paid dividends and have strong dividend
policies). In addition to investments in domestic securities, the Fund may invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.

Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Growth & Income Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in a mix of growth equity securities and income producing securities, with no minimum or maximum investment requirements specified for either category.
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Growth & Income Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Growth & Income Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 9.78%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 19.93%
Worst Quarter: March 31, 2020 = -20.35%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Russell 3000® Index has replaced the Russell 1000® Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Growth & Income Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Growth & Income Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be
higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Growth & Income Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Growth & Income Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Growth & Income Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Growth & Income Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Growth & Income Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Growth & Income Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Growth & Income Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Growth & Income Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Growth & Income Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo Growth & Income Fund | Dividend Strategy Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Dividend Strategy Risk – Strategies focusing on dividend-paying stocks may fall out of investor favor, which may negatively affect the performance of stocks that pay dividends regardless of whether the underlying companies’ business fortunes have changed. The Adviser may incorrectly judge whether a company will be able to continue paying dividends or the amount of such dividends, which may cause losses for the Fund.
Buffalo Growth & Income Fund | Large-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Large-Cap Company Risk – Larger, more established companies may be unable to respond quickly to new competitive challenges and are sometimes unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.
Buffalo Growth & Income Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Growth & Income Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Growth & Income Fund | Small-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Small-Cap Company Risk – Investing in small-cap companies may involve greater risk than investing in large- or mid-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than mid- and large-cap companies. In addition, small-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Growth & Income Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Growth & Income Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Growth & Income Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Growth & Income Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Growth & Income Fund | Russell 1000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 1000® Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 26.53%
5 Years rr_AverageAnnualReturnYear05 15.52%
10 Years rr_AverageAnnualReturnYear10 11.80%
Buffalo Growth & Income Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index*(reflects no deduction for fees, expenses or taxes) [3]
1 Year rr_AverageAnnualReturnYear01 25.96% [3]
5 Years rr_AverageAnnualReturnYear05 15.16% [3]
10 Years rr_AverageAnnualReturnYear10 11.48% [3]
Buffalo Growth & Income Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFDX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.15%
Other Expenses rr_Component2OtherExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.94% [4]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 96
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 300
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 520
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,155
Annual Return 2014 rr_AnnualReturn2014 20.81%
Annual Return 2015 rr_AnnualReturn2015 0.13%
Annual Return 2016 rr_AnnualReturn2016 12.06%
Annual Return 2017 rr_AnnualReturn2017 18.02%
Annual Return 2018 rr_AnnualReturn2018 (5.05%)
Annual Return 2019 rr_AnnualReturn2019 27.66%
Annual Return 2020 rr_AnnualReturn2020 16.64%
Annual Return 2021 rr_AnnualReturn2021 20.97%
Annual Return 2022 rr_AnnualReturn2022 (8.75%)
Annual Return 2023 rr_AnnualReturn2023 20.06%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.78%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.93%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.35%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 20.06%
5 Years rr_AverageAnnualReturnYear05 14.56%
10 Years rr_AverageAnnualReturnYear10 11.60%
Buffalo Growth & Income Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 19.48%
5 Years rr_AverageAnnualReturnYear05 14.12%
10 Years rr_AverageAnnualReturnYear10 10.82%
Buffalo Growth & Income Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 12.25%
5 Years rr_AverageAnnualReturnYear05 11.66%
10 Years rr_AverageAnnualReturnYear10 9.34%
Buffalo Growth & Income Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUIDX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.79% [4]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 81
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 252
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 439
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 978
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 20.21%
5 Years rr_AverageAnnualReturnYear05 14.73%
10 Years rr_AverageAnnualReturnYear10 11.77%
Buffalo Early Stage Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO EARLY STAGE GROWTH FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the Buffalo Early Stage Growth Fund (“Early Stage Growth Fund” or the “Fund”) is 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 20% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 20.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Early Stage Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “early stage growth companies.” Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), defines early stage companies as companies, at the time of purchase, with market capitalizations below the weighted average of the Russell 2000® Growth Index and are starting to develop a new product or service or have recently developed a new product or service. As of June 30, 2024, the weighted average market capitalization of the Russell 2000® Growth Index was $3.7 billion. KCM defines growth companies as companies that, at the time of purchase, are constituents of the Russell 3000® Growth Index or exhibit growth characteristics (generates positive cash
flows or earnings that increase at faster rates than the overall economy) consistent with inclusion of companies in the Russell 3000® Growth Index. Companies included in the Fund’s investment universe must satisfy both prongs of KCM’s definition of an early stage growth company. In addition to the Fund’s investments in domestic securities, the Fund may also invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.

Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. Currently, the Fund has significant investments in the industrials sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Early Stage Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “early stage growth companies.”
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Early Stage Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Early Stage Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 1.49%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 40.64%
Worst Quarter: March 31, 2020 = -25.33%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Russell 3000® Index has replaced the Russell 2000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Early Stage Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Early Stage Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Early Stage Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Early Stage Growth Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Early Stage Growth Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for
the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Early Stage Growth Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Early Stage Growth Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Early Stage Growth Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Early Stage Growth Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Early Stage Growth Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for
the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Early Stage Growth Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.
Industrials Sector Risk. Issuers in the industrials sector are affected by supply and demand, both for their specific product or service and for industrials sector products in general. The products of such issuers may face obsolescence due to rapid technological developments and frequent new product introduction. Government regulations, world events, economic conditions and exchange rates affect the performance of companies in the industrials sector. Issuers in the industrials sector may be adversely affected by liability for environmental damage, product liability claims and exchange rates. The industrials sector may also be adversely affected by changes or trends in commodity prices that may be influenced by unpredictable factors.
Buffalo Early Stage Growth Fund | Sector Risk, Industrials Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Industrials Sector Risk. Issuers in the industrials sector are affected by supply and demand, both for their specific product or service and for industrials sector products in general. The products of such issuers may face obsolescence due to rapid technological developments and frequent new product introduction. Government regulations, world events, economic conditions and exchange rates affect the performance of companies in the industrials sector. Issuers in the industrials sector may be adversely affected by liability for environmental damage, product liability claims and exchange rates. The industrials sector may also be adversely affected by changes or trends in commodity prices that may be influenced by unpredictable factors.
Buffalo Early Stage Growth Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo Early Stage Growth Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Early Stage Growth Fund | Micro-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Micro-Cap Company Risk – Investing in micro-cap companies may involve greater risk than investing in companies with larger capitalization due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than companies with larger capitalization. In addition, micro-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans. The trading volume of securities of smaller capitalization companies is normally less than that of larger capitalization companies, and therefore may disproportionately affect their market price, tending to make them fall more in response to selling pressure than is the case with larger capitalization companies. These risks are enhanced for micro-cap securities. Many micro-cap companies tend to be new and have no proven track record. Some of these companies have no assets or operations, while others have products and services that are still in development or have yet to be tested in the market. As any size of trade can have a large percentage impact on the price of a micro-cap stock, the Fund will be more susceptible to sudden and significant losses. In addition, micro-cap company stocks will also be bought and sold less often than other stocks, making them less liquid than other securities. Because of this, if the Fund wants to sell a large quantity of a micro-cap company’s stock, it may have to sell at a lower price than the Adviser might prefer, or it may have to sell in smaller than desired quantities over a period of time. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to bear the risk of these fluctuations.
Buffalo Early Stage Growth Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Early Stage Growth Fund | Small-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Small-Cap Company Risk – Investing in small-cap companies may involve greater risk than investing in large- or mid-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than mid- and large-cap companies. In addition, small-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Early Stage Growth Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Early Stage Growth Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different
regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Early Stage Growth Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Early Stage Growth Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Early Stage Growth Fund | Russell 2000® Growth Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 2000® Growth Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 18.66%
5 Years rr_AverageAnnualReturnYear05 9.22%
10 Years rr_AverageAnnualReturnYear10 7.16%
Buffalo Early Stage Growth Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index*(reflects no deduction for fees, expenses or taxes) [5]
1 Year rr_AverageAnnualReturnYear01 25.96% [5]
5 Years rr_AverageAnnualReturnYear05 15.16% [5]
10 Years rr_AverageAnnualReturnYear10 11.48% [5]
Buffalo Early Stage Growth Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFOX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.30%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.10% [6]
Other Expenses rr_Component2OtherExpensesOverAssets 0.05%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.45% [7]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 148
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 459
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 792
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,735
Annual Return 2014 rr_AnnualReturn2014 (7.38%)
Annual Return 2015 rr_AnnualReturn2015 (9.41%)
Annual Return 2016 rr_AnnualReturn2016 11.05%
Annual Return 2017 rr_AnnualReturn2017 27.18%
Annual Return 2018 rr_AnnualReturn2018 (3.95%)
Annual Return 2019 rr_AnnualReturn2019 34.03%
Annual Return 2020 rr_AnnualReturn2020 47.69%
Annual Return 2021 rr_AnnualReturn2021 7.79%
Annual Return 2022 rr_AnnualReturn2022 (30.76%)
Annual Return 2023 rr_AnnualReturn2023 9.83%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 1.49%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 40.64%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.33%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.83%
5 Years rr_AverageAnnualReturnYear05 10.16%
10 Years rr_AverageAnnualReturnYear10 6.33%
Buffalo Early Stage Growth Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.83%
5 Years rr_AverageAnnualReturnYear05 8.28%
10 Years rr_AverageAnnualReturnYear10 3.81%
Buffalo Early Stage Growth Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 5.82%
5 Years rr_AverageAnnualReturnYear05 7.96%
10 Years rr_AverageAnnualReturnYear10 4.30%
Buffalo Early Stage Growth Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUIOX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.30%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.05%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.35% [7]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 137
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 428
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 739
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,624
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.98%
5 Years rr_AverageAnnualReturnYear05 10.33%
10 Years rr_AverageAnnualReturnYear10 6.48%
Buffalo Flexible Allocation Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO FLEXIBLE ALLOCATION FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVES
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The investment objective of the Buffalo Flexible Allocation Fund (“Flexible Allocation Fund” or the “Fund”) (formerly known as “Buffalo Flexible Income Fund”) is the generation of high current income and,
Objective, Secondary [Text Block] rr_ObjectiveSecondaryTextBlock as a secondary objective, the 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 1% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 1.00%
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Flexible Allocation Fund may invest in both equity and debt securities. The allocation of assets invested in each type of security is designed to primarily achieve high current income, with a secondary objective of long-term capital appreciation. The Fund expects to change its allocation mix over time based on Kornitzer Capital Management, Inc.’s, the Fund’s investment adviser (the “Adviser” or “KCM”), view of economic conditions and underlying security values. The Fund retains the right to invest up to 100% of its net assets in equity securities or up to 100% of its net assets in debt securities. Equity securities may include common stocks, preferred stocks, convertible securities, rights, and warrants. Debt securities may include government notes and bonds; mortgage and asset backed securities; bank debt; convertible securities; fixed and floating rate corporate debt securities, both rated and unrated; and higher-yielding, higher-risk debt securities rated below investment grade by the major rating agencies (or in similar unrated securities), commonly known as “junk bonds.” In addition to the Fund’s investments in domestic securities, the Fund may also invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.
Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. Currently, the Fund has significant investments in the energy sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Fund retains the right to invest up to 100% of its net assets in equity securities or up to 100% of its net assets in debt securities.
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Flexible Allocation Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance. The Fund’s past
performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Flexible Allocation Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 10.55%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 17.00%
Worst Quarter: March 31, 2020 = -24.32%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Flexible Allocation Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Flexible Allocation Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Flexible Allocation Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Flexible Allocation Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Flexible Allocation Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Flexible Allocation Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Flexible Allocation Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Flexible Allocation Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Flexible Allocation Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Flexible Allocation Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Flexible Allocation Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.
Energy Sector Risk. The energy sector includes companies operating in the exploration and production, refining and marketing, and storage and transportation of oil and gas and coal and consumable fuels. It also includes companies that offer oil and gas equipment and related services. The Fund is subject to the risk that the securities of such issuers will underperform the market as a whole due to legislative or regulatory changes, adverse market conditions and/or increased competition affecting the energy sector. The performance of companies operating in the energy sector is closely tied to the price and supply of energy fuels and international political events.
Buffalo Flexible Allocation Fund | Sector Risk, Energy Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Energy Sector Risk. The energy sector includes companies operating in the exploration and production, refining and marketing, and storage and transportation of oil and gas and coal and consumable fuels. It also includes companies that offer oil and gas equipment and related services. The Fund is subject to the risk that the securities of such issuers will underperform the market as a whole due to legislative or regulatory changes, adverse market conditions and/or increased competition affecting the energy sector. The performance of companies operating in the energy sector is closely tied to the price and supply of energy fuels and international political events.
Buffalo Flexible Allocation Fund | Large-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Large-Cap Company Risk – Larger, more established companies may be unable to respond quickly to new competitive challenges and are sometimes unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.
Buffalo Flexible Allocation Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Flexible Allocation Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Flexible Allocation Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Flexible Allocation Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Flexible Allocation Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Flexible Allocation Fund | Debt Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Debt Securities Risk – The values of debt securities may increase or decrease as a result of the following: market fluctuations, changes in interest rates, actual or perceived inability or unwillingness of issuers, guarantors or liquidity providers to make scheduled principal or interest payments or illiquidity in debt securities markets; the risk of low rates of return due to reinvestment of securities during periods of falling interest rates or repayment by issuers with higher coupon or interest rates; the risk of loss of value due to increases in interest rates and/or the risk of low income due to falling interest rates.
Buffalo Flexible Allocation Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Flexible Allocation Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.96%
5 Years rr_AverageAnnualReturnYear05 15.16%
10 Years rr_AverageAnnualReturnYear10 11.48%
Buffalo Flexible Allocation Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFBX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.15%
Other Expenses rr_Component2OtherExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.01%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 103
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 322
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 558
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,236
Annual Return 2014 rr_AnnualReturn2014 3.59%
Annual Return 2015 rr_AnnualReturn2015 (1.97%)
Annual Return 2016 rr_AnnualReturn2016 9.90%
Annual Return 2017 rr_AnnualReturn2017 13.21%
Annual Return 2018 rr_AnnualReturn2018 (7.00%)
Annual Return 2019 rr_AnnualReturn2019 18.76%
Annual Return 2020 rr_AnnualReturn2020 (2.24%)
Annual Return 2021 rr_AnnualReturn2021 30.00%
Annual Return 2022 rr_AnnualReturn2022 4.01%
Annual Return 2023 rr_AnnualReturn2023 7.43%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 10.55%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.00%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.32%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 7.43%
5 Years rr_AverageAnnualReturnYear05 11.02%
10 Years rr_AverageAnnualReturnYear10 7.08%
Buffalo Flexible Allocation Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 6.53%
5 Years rr_AverageAnnualReturnYear05 9.99%
10 Years rr_AverageAnnualReturnYear10 6.04%
Buffalo Flexible Allocation Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 5.00%
5 Years rr_AverageAnnualReturnYear05 8.63%
10 Years rr_AverageAnnualReturnYear10 5.46%
Buffalo Flexible Allocation Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUIBX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 7.53%
5 Years rr_AverageAnnualReturnYear05 11.17%
10 Years rr_AverageAnnualReturnYear10 7.23%
Buffalo Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO GROWTH FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the Buffalo Growth Fund (“Growth Fund” or the “Fund”) is 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 9% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 9.00%
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “growth companies.” Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), defines growth companies as companies that, at the time of purchase, are constituents of the Russell 3000® Growth Index or exhibit growth characteristics (generates positive cash flows or earnings that increase at faster rates than the overall economy) consistent with inclusion of companies in the Russell 3000® Growth Index. In addition to the Fund’s investments in domestic securities, the Fund may also invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.

Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. Currently, the Fund has
significant investments in the information technology sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.

The Fund is classified as a “non-diversified” investment company under the Investment Company Act of 1940 (the “1940 Act”).
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “growth companies.”
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 15.45%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 24.48%
Worst Quarter: June 30, 2022 = -21.02%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Russell 3000® Index has replaced the Russell 3000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Growth Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Growth Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Growth Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Growth Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Growth Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Growth Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Growth Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Growth Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.

Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Growth Fund | Sector Risk, Information Technology Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Growth Fund | Risk Nondiversified Status [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Non-Diversification Risk – Because the Fund is “non-diversified,” it may invest a greater percentage of its assets in the securities of a single issuer or a lesser number of issuers than if it was a diversified fund. As a result, a decline in the value of an investment in a single issuer or a small number of issuers could cause the Fund’s overall value to decline to a greater degree than if the Fund held a more diversified portfolio. This may increase the Fund’s volatility
and cause the performance of a relatively smaller number of issuers to have a greater impact on the Fund’s performance.
Buffalo Growth Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo Growth Fund | Large-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Large-Cap Company Risk – Larger, more established companies may be unable to respond quickly to new competitive challenges and are sometimes unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.
Buffalo Growth Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Growth Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Growth Fund | Small-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Small-Cap Company Risk – Investing in small-cap companies may involve greater risk than investing in large- or mid-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than mid- and large-cap companies. In addition, small-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Growth Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Growth Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Growth Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Growth Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Growth Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index*(reflects no deduction for fees, expenses or taxes) [8]
1 Year rr_AverageAnnualReturnYear01 25.96% [8]
5 Years rr_AverageAnnualReturnYear05 15.16% [8]
10 Years rr_AverageAnnualReturnYear10 11.48% [8]
Buffalo Growth Fund | Russell 3000® Growth Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Growth Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 41.21%
5 Years rr_AverageAnnualReturnYear05 18.85%
10 Years rr_AverageAnnualReturnYear10 14.33%
Buffalo Growth Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFGX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.10% [9]
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 482
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,073
Annual Return 2014 rr_AnnualReturn2014 8.88%
Annual Return 2015 rr_AnnualReturn2015 2.64%
Annual Return 2016 rr_AnnualReturn2016 4.86%
Annual Return 2017 rr_AnnualReturn2017 22.81%
Annual Return 2018 rr_AnnualReturn2018 0.51%
Annual Return 2019 rr_AnnualReturn2019 31.91%
Annual Return 2020 rr_AnnualReturn2020 28.29%
Annual Return 2021 rr_AnnualReturn2021 21.69%
Annual Return 2022 rr_AnnualReturn2022 (31.13%)
Annual Return 2023 rr_AnnualReturn2023 42.64%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 15.45%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.48%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.02%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 42.64%
5 Years rr_AverageAnnualReturnYear05 15.13%
10 Years rr_AverageAnnualReturnYear10 11.34%
Buffalo Growth Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 40.78%
5 Years rr_AverageAnnualReturnYear05 13.15%
10 Years rr_AverageAnnualReturnYear10 8.35%
Buffalo Growth Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 26.47%
5 Years rr_AverageAnnualReturnYear05 11.90%
10 Years rr_AverageAnnualReturnYear10 8.34%
Buffalo Growth Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BIIGX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.77%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 79
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 246
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 428
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 954
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 42.79%
5 Years rr_AverageAnnualReturnYear05 15.29%
10 Years rr_AverageAnnualReturnYear10 11.50%
Buffalo High Yield Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO HIGH YIELD FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The investment objective of the Buffalo High Yield Fund (“High Yield Fund” or the “Fund”) is current income,
Objective, Secondary [Text Block] rr_ObjectiveSecondaryTextBlock with long-term growth of capital as a secondary objective.
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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 26% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 26.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The High Yield Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in higher-yielding, higher-risk debt securities rated below investment grade by the major rating agencies (or in similar unrated securities), commonly known as “junk bonds.” Debt securities may include fixed and floating rate bonds, bank debt, and convertible debt securities. With respect to the remaining 20% of the Fund’s net assets, the Fund may invest in securities such as investment grade debt securities, U.S. Treasury Securities (typically with maturities of 60 days or less), money market funds, and equity investments, including dividend paying stocks, convertible stocks, and preferred stocks. The Fund may invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges and U.S. over-the-counter markets.
The Fund maintains a flexible investment policy which allows it to invest in debt securities with varying maturities. The lowest rated debt security that the Fund will hold is D quality (defaulted securities). Although the Fund will not purchase D quality debt securities, the Fund may continue to hold these securities and will sell them at the discretion of Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”). The Fund has no limitation on principal, interest, or reset terms on debt securities held in the Fund.

The Adviser performs extensive fundamental investment research to identify investment opportunities for the Fund. When evaluating investments and the credit quality of rated and unrated securities, the Adviser looks at a number of past, present, and estimated future factors, including: (1) financial strength of the issuer; (2) cash flow; (3) management; (4) borrowing requirements; (5) sensitivity to changes in interest rates and business conditions; and (6) relative value. The Fund may invest in companies in any sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The High Yield Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in higher-yielding, higher-risk debt securities rated below investment grade by the major rating agencies (or in similar unrated securities), commonly known as “junk bonds.”
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the High Yield Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the High Yield Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 4.32%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 10.00%
Worst Quarter: March 31, 2020 = -12.52%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Bloomberg Universal Bond Index has replaced the ICE BofA US High Yield® Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the High Yield Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the High Yield Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo High Yield Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo High Yield Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo High Yield Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo High Yield Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although
money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo High Yield Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo High Yield Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo High Yield Fund | Debt Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Debt Securities Risk – The values of debt securities may increase or decrease as a result of the following: market fluctuations, changes in interest rates, actual or perceived inability or unwillingness of issuers, guarantors or liquidity providers to make scheduled principal or interest payments or illiquidity in debt securities markets; the risk of low rates of return due to reinvestment of securities during periods of falling interest rates or repayment by issuers with higher coupon or interest rates; the risk of loss of value due to increases in interest rates and/or the risk of low income due to falling interest rates.
Buffalo High Yield Fund | High Yield Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
High Yield Risk – The Fund may invest in higher-yielding, high-risk bonds commonly known as junk bonds. These lower-rated bonds have a greater degree of default risk. Lower-rated securities may be issued by companies that are restructuring, are smaller and less credit worthy or are highly indebted, and tend to be less liquid and react more poorly to adverse economic and political changes, unfavorable investor perceptions and negative corporate developments.
Buffalo High Yield Fund | Bank Loan Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Bank Loan Risk – The Fund’s investments in secured and unsecured participations in bank loans and assignments of such loans may create substantial risk. In making investments in such loans that banks or other financial intermediaries make to borrowers, the Fund will depend primarily upon the creditworthiness of the borrower for payment of principal and interest. If the Fund does not receive scheduled interest or principal payments on such indebtedness, the Fund’s share price could be adversely affected. The Fund may invest in loan participations that are rated by a nationally recognized statistical rating organization or are unrated, and may invest in loan participations of any credit quality, including loans to “distressed” companies with respect to which there is a substantial risk of losing the entire amount invested. In addition, certain bank loans in which the Fund may invest may be illiquid and, therefore, difficult to value and/or sell at a price that is beneficial to the Fund.
Buffalo High Yield Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo High Yield Fund | Bloomberg Universal Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg Universal Bond Index*(reflects no deduction for fees, expenses or taxes) [10]
1 Year rr_AverageAnnualReturnYear01 6.17% [10]
5 Years rr_AverageAnnualReturnYear05 1.44% [10]
10 Years rr_AverageAnnualReturnYear10 2.08% [10]
Buffalo High Yield Fund | ICE BofA US High Yield Index® (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel ICE BofA US High Yield Index®(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 13.54%
5 Years rr_AverageAnnualReturnYear05 5.24%
10 Years rr_AverageAnnualReturnYear10 4.53%
Buffalo High Yield Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFHX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.15%
Other Expenses rr_Component2OtherExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.03% [11]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 105
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 328
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 569
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,259
Annual Return 2014 rr_AnnualReturn2014 1.96%
Annual Return 2015 rr_AnnualReturn2015 1.80%
Annual Return 2016 rr_AnnualReturn2016 6.65%
Annual Return 2017 rr_AnnualReturn2017 5.98%
Annual Return 2018 rr_AnnualReturn2018 (2.26%)
Annual Return 2019 rr_AnnualReturn2019 12.32%
Annual Return 2020 rr_AnnualReturn2020 9.27%
Annual Return 2021 rr_AnnualReturn2021 5.53%
Annual Return 2022 rr_AnnualReturn2022 (5.53%)
Annual Return 2023 rr_AnnualReturn2023 11.68%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 4.32%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.00%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.52%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.68%
5 Years rr_AverageAnnualReturnYear05 6.44%
10 Years rr_AverageAnnualReturnYear10 4.59%
Buffalo High Yield Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 8.74%
5 Years rr_AverageAnnualReturnYear05 3.98%
10 Years rr_AverageAnnualReturnYear10 2.35%
Buffalo High Yield Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 6.83%
5 Years rr_AverageAnnualReturnYear05 3.95%
10 Years rr_AverageAnnualReturnYear10 2.59%
Buffalo High Yield Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUIHX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87% [11]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 482
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,073
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.85%
5 Years rr_AverageAnnualReturnYear05 6.59%
10 Years rr_AverageAnnualReturnYear10 4.74%
Buffalo International Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO INTERNATIONAL FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the Buffalo International Fund (“International Fund” or the “Fund”) is 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 1% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 1.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The International Fund primarily invests in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, rights, and depositary receipts of established companies that are economically tied to various countries throughout the world (excluding the U.S.). The Fund may invest directly or indirectly in foreign securities or foreign currencies of both developed and developing countries. For purposes of the Fund’s investments, “foreign securities” means those securities issued by companies:
•that are organized under the laws of, or with a principal office in, a country other than the U.S. and issue securities for which the principal trading market is in a country other than the U.S.; or
•that derive at least 50% of their revenues or profits from goods produced or sold, investments made, or services provided in a country other than the U.S., or have at least 50% of their assets in a country other than the U.S.

Under normal circumstances, the Fund does not expect its investments in emerging markets to exceed 35% of its net assets. The Fund’s investments in depositary receipts (“DRs”) may include sponsored or unsponsored American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”), or Global Depositary Receipts (“GDRs”).

Companies are screened using in-depth, in-house research to identify those which Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. In making portfolio selections for the Fund, the Adviser will also consider the economic, political, and market conditions of the various countries in which the Fund may invest. The Fund may invest in companies in any sector. The Fund may have significant investments in the information technology sector. The Adviser may sell the International Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration Under normal circumstances, the Fund does not expect its investments in emerging markets to exceed 35% of its net assets.
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the International Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the International Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 2.74%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 18.82%
Worst Quarter: March 31, 2020 = -19.78%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The FTSE Global All Cap ex US Index has replaced the FTSE All-World ex US Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the International Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the International Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo International Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo International Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo International Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently
exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo International Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo International Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo International Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo International Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently
exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo International Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo International Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.

Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo International Fund | Sector Risk, Information Technology Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo International Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo International Fund | Large-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Large-Cap Company Risk – Larger, more established companies may be unable to respond quickly to new competitive challenges and are sometimes unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.
Buffalo International Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo International Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo International Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo International Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

Depositary Receipts. Unsponsored DRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored DRs than sponsored DRs. Unsponsored DRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, EDRs and GDRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo International Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Depositary Receipts. Unsponsored DRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored DRs than sponsored DRs. Unsponsored DRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, EDRs and GDRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo International Fund | Emerging Markets Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Emerging Markets Risk – Emerging markets are markets of countries, such as China, the Philippines and India, in the initial stages of industrialization and that generally have low per capita income. In addition to the risks of foreign securities in general, emerging markets are generally more volatile, have relatively unstable governments, social and legal systems that do not protect shareholders, economies based on only a few industries and securities markets that are substantially smaller, less liquid and more volatile with less government oversight than more developed countries. Emerging markets securities or companies may be subject to the risk of nationalization or may be subject to the control of the country in which such companies are domiciled. Additionally, the Fund may have investments in companies located in China. Risks associated with investments in China include risks related to governmental policies and risks to the economy from trade or political disputes with China’s trading partners.
Buffalo International Fund | Currency Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Currency Risk – When the Fund buys or sells securities on a foreign stock exchange, the transaction is undertaken in the local currency rather than in U.S. dollars, which carries the risk that the value of the foreign currency will increase or decrease, and may impact the value of the Fund’s portfolio holdings and your investment. China and other countries may adopt economic policies and/or currency exchange controls that affect its currency valuations in a disadvantageous manner for U.S. investors and companies and restrict or prohibit the Fund’s ability to repatriate both investment capital and income, which could place the Fund’s assets at risk of total loss.
Buffalo International Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo International Fund | FTSE Global All Cap ex US Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel FTSE Global All Cap ex US Index*(reflects no deduction for fees, expenses or taxes) [12]
1 Year rr_AverageAnnualReturnYear01 16.17% [12]
5 Years rr_AverageAnnualReturnYear05 7.78% [12]
10 Years rr_AverageAnnualReturnYear10 4.51% [12]
Buffalo International Fund | FTSE All-World ex US Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel FTSE All-World ex US Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 16.20%
5 Years rr_AverageAnnualReturnYear05 7.85%
10 Years rr_AverageAnnualReturnYear10 4.55%
Buffalo International Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFIX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.15%
Other Expenses rr_Component2OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [13]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.05% [14]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 334
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 579
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,283
Annual Return 2014 rr_AnnualReturn2014 (2.04%)
Annual Return 2015 rr_AnnualReturn2015 (0.45%)
Annual Return 2016 rr_AnnualReturn2016 3.19%
Annual Return 2017 rr_AnnualReturn2017 29.33%
Annual Return 2018 rr_AnnualReturn2018 (8.85%)
Annual Return 2019 rr_AnnualReturn2019 28.02%
Annual Return 2020 rr_AnnualReturn2020 19.10%
Annual Return 2021 rr_AnnualReturn2021 18.21%
Annual Return 2022 rr_AnnualReturn2022 (21.79%)
Annual Return 2023 rr_AnnualReturn2023 18.33%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 2.74%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.82%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.78%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.33%
5 Years rr_AverageAnnualReturnYear05 10.77%
10 Years rr_AverageAnnualReturnYear10 7.06%
Buffalo International Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 18.27%
5 Years rr_AverageAnnualReturnYear05 10.67%
10 Years rr_AverageAnnualReturnYear10 6.97%
Buffalo International Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 11.08%
5 Years rr_AverageAnnualReturnYear05 8.70%
10 Years rr_AverageAnnualReturnYear10 5.83%
Buffalo International Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUIIX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [13]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.90% [14]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 287
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 498
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,108
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.47%
5 Years rr_AverageAnnualReturnYear05 10.94%
10 Years rr_AverageAnnualReturnYear10 7.22%
Buffalo Blue Chip Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO BLUE CHIP GROWTH FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the Buffalo Blue Chip Growth Fund (“Blue Chip Growth Fund” or the “Fund”) (formerly known as “Buffalo Large Cap Fund”) is 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 36% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 36.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Blue Chip Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “blue chip growth companies.” Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), defines blue chip companies as companies that, at the time of purchase, are nationally recognized, well established in their industries, financially sound and usually have higher market capitalizations. KCM defines growth
companies as companies that, at the time of purchase, are constituents of the Russell 3000® Growth Index or exhibit growth characteristics (generates positive cash flows or earnings that increase at faster rates than the overall economy) consistent with inclusion of companies in the Russell 3000® Growth Index. Companies included in the Fund’s investment universe must satisfy both prongs of KCM’s definition of blue chip growth company. In addition to the Fund’s investments in domestic securities, the Fund may also invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.

Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. Currently, the Fund has significant investments in the information technology sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.

The Fund is classified as a “non-diversified” investment company under the Investment Company Act of 1940 (the “1940 Act”).
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Blue Chip Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “blue chip growth companies.”
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Blue Chip Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Blue Chip Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = 21.25%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 24.25%
Worst Quarter: June 30, 2022 = -19.47%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Russell 3000® Index has replaced the Russell 1000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Blue Chip Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Blue Chip Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Blue Chip Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Blue Chip Growth Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Blue Chip Growth Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently
exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Blue Chip Growth Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Blue Chip Growth Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Blue Chip Growth Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Blue Chip Growth Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently
exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Blue Chip Growth Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Blue Chip Growth Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.

Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Blue Chip Growth Fund | Sector Risk, Information Technology Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Blue Chip Growth Fund | Risk Nondiversified Status [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Non-Diversification Risk – Because the Fund is “non-diversified,” it may invest a greater percentage of its assets in the securities of a single issuer or a lesser number of issuers than if it was a diversified fund. As a result, a decline in the value of an investment in a single issuer or a small number of issuers could cause the Fund’s overall value to decline to a greater degree than if the Fund held a more diversified portfolio. This may increase the Fund’s volatility and cause the performance of a relatively smaller number of issuers to have a greater impact on the Fund’s performance.
Buffalo Blue Chip Growth Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo Blue Chip Growth Fund | Large-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Large-Cap Company Risk – Larger, more established companies may be unable to respond quickly to new competitive challenges and are sometimes unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.
Buffalo Blue Chip Growth Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Blue Chip Growth Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Blue Chip Growth Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Blue Chip Growth Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Blue Chip Growth Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Blue Chip Growth Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Blue Chip Growth Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index*(reflects no deduction for fees, expenses or taxes) [15]
1 Year rr_AverageAnnualReturnYear01 25.96% [15]
5 Years rr_AverageAnnualReturnYear05 15.16% [15]
10 Years rr_AverageAnnualReturnYear10 11.48% [15]
Buffalo Blue Chip Growth Fund | Russell 1000® Growth Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 1000® Growth Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 42.68%
5 Years rr_AverageAnnualReturnYear05 19.50%
10 Years rr_AverageAnnualReturnYear10 14.86%
Buffalo Blue Chip Growth Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFEX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.10% [16]
Other Expenses rr_Component2OtherExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.89% [17]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 284
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 493
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,096
Annual Return 2014 rr_AnnualReturn2014 12.76%
Annual Return 2015 rr_AnnualReturn2015 7.15%
Annual Return 2016 rr_AnnualReturn2016 6.90%
Annual Return 2017 rr_AnnualReturn2017 24.86%
Annual Return 2018 rr_AnnualReturn2018 (1.63%)
Annual Return 2019 rr_AnnualReturn2019 31.77%
Annual Return 2020 rr_AnnualReturn2020 28.08%
Annual Return 2021 rr_AnnualReturn2021 26.08%
Annual Return 2022 rr_AnnualReturn2022 (28.61%)
Annual Return 2023 rr_AnnualReturn2023 40.39%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 21.25%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.25%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.47%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 40.39%
5 Years rr_AverageAnnualReturnYear05 16.35%
10 Years rr_AverageAnnualReturnYear10 12.96%
Buffalo Blue Chip Growth Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 40.38%
5 Years rr_AverageAnnualReturnYear05 14.91%
10 Years rr_AverageAnnualReturnYear10 11.34%
Buffalo Blue Chip Growth Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 23.92%
5 Years rr_AverageAnnualReturnYear05 13.14%
10 Years rr_AverageAnnualReturnYear10 10.31%
Buffalo Blue Chip Growth Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUIEX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.79% [17]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 81
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 252
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 439
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 978
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 40.52%
5 Years rr_AverageAnnualReturnYear05 16.52%
10 Years rr_AverageAnnualReturnYear10 13.13%
Buffalo Mid Cap Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO MID CAP GROWTH FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the Buffalo Mid Cap Growth Fund (“Mid Cap Growth Fund” or the “Fund”) (formerly known as “Buffalo Mid Cap Fund”) is 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 17% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 17.00%
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Mid Cap Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “mid-cap growth companies.” Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), defines mid-cap companies as companies, at the time of purchase, with market capitalizations within the range of the Russell Midcap® Growth Index. As of June 30, 2024, the range of market capitalizations of the Russell Midcap® Growth Index was $658 million to $61.6 billion. KCM defines growth companies as companies that, at the time of purchase, are constituents of the Russell 3000® Growth Index or exhibit growth characteristics (generates positive cash flows or earnings that increase at faster rates than the overall economy) consistent with inclusion of companies in the Russell 3000® Growth Index. Companies included in the Fund’s investment universe must satisfy both prongs of KCM’s definition of mid-cap growth company. In addition to the Fund’s investments in domestic securities, the Fund may also invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.
Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. Currently, the Fund has significant investments in the information technology sector. The Fund may have significant investments in the industrials sector. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Mid Cap Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “mid-cap growth companies.”
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Mid Cap Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Mid Cap Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = -1.78%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 22.66%
Worst Quarter: June 30, 2022 = -21.67%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Russell 3000® Index has replaced the Russell Midcap® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Mid Cap Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Mid Cap Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Mid Cap Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Mid Cap Growth Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Mid Cap Growth Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Mid Cap Growth Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Mid Cap Growth Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Mid Cap Growth Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Mid Cap Growth Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Mid Cap Growth Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Mid Cap Growth Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.

Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.

Industrials Sector Risk. Issuers in the industrials sector are affected by supply and demand, both for their specific product or service and for industrials sector products in general. The products of such issuers may face obsolescence due to rapid technological developments and frequent new product introduction. Government regulations, world events, economic conditions and exchange rates affect the performance of companies in the industrials sector. Issuers in the industrials sector may be adversely affected by liability for environmental damage, product liability claims and exchange rates. The industrials sector may also be adversely affected by changes or trends in commodity prices that may be influenced by unpredictable factors.
Buffalo Mid Cap Growth Fund | Sector Risk, Industrials Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Industrials Sector Risk. Issuers in the industrials sector are affected by supply and demand, both for their specific product or service and for industrials sector products in general. The products of such issuers may face obsolescence due to rapid technological developments and frequent new product introduction. Government regulations, world events, economic conditions and exchange rates affect the performance of companies in the industrials sector. Issuers in the industrials sector may be adversely affected by liability for environmental damage, product liability claims and exchange rates. The industrials sector may also be adversely affected by changes or trends in commodity prices that may be influenced by unpredictable factors.
Buffalo Mid Cap Growth Fund | Sector Risk, Information Technology Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Mid Cap Growth Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment
style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo Mid Cap Growth Fund | Large-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Large-Cap Company Risk – Larger, more established companies may be unable to respond quickly to new competitive challenges and are sometimes unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.
Buffalo Mid Cap Growth Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Mid Cap Growth Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Mid Cap Growth Fund | Small-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Small-Cap Company Risk – Investing in small-cap companies may involve greater risk than investing in large- or mid-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than mid- and large-cap companies. In addition, small-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Mid Cap Growth Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Mid Cap Growth Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated
to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Mid Cap Growth Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated
to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Mid Cap Growth Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Mid Cap Growth Fund | Russell Midcap® Growth Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell Midcap® Growth Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.87%
5 Years rr_AverageAnnualReturnYear05 13.81%
10 Years rr_AverageAnnualReturnYear10 10.57%
Buffalo Mid Cap Growth Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index*(reflects no deduction for fees, expenses or taxes) [18]
1 Year rr_AverageAnnualReturnYear01 25.96% [18]
5 Years rr_AverageAnnualReturnYear05 15.16% [18]
10 Years rr_AverageAnnualReturnYear10 11.48% [18]
Buffalo Mid Cap Growth Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFMX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.10% [19]
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.97%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 99
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 309
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 536
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,190
Annual Return 2014 rr_AnnualReturn2014 5.85%
Annual Return 2015 rr_AnnualReturn2015 (0.52%)
Annual Return 2016 rr_AnnualReturn2016 5.93%
Annual Return 2017 rr_AnnualReturn2017 13.66%
Annual Return 2018 rr_AnnualReturn2018 (7.30%)
Annual Return 2019 rr_AnnualReturn2019 37.98%
Annual Return 2020 rr_AnnualReturn2020 34.18%
Annual Return 2021 rr_AnnualReturn2021 14.61%
Annual Return 2022 rr_AnnualReturn2022 (27.80%)
Annual Return 2023 rr_AnnualReturn2023 26.97%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (1.78%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.66%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.67%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 26.97%
5 Years rr_AverageAnnualReturnYear05 14.23%
10 Years rr_AverageAnnualReturnYear10 8.62%
Buffalo Mid Cap Growth Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 25.37%
5 Years rr_AverageAnnualReturnYear05 12.22%
10 Years rr_AverageAnnualReturnYear10 6.14%
Buffalo Mid Cap Growth Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 16.97%
5 Years rr_AverageAnnualReturnYear05 11.19%
10 Years rr_AverageAnnualReturnYear10 6.27%
Buffalo Mid Cap Growth Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUIMX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 482
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,073
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 27.18%
5 Years rr_AverageAnnualReturnYear05 14.40%
10 Years rr_AverageAnnualReturnYear10 8.78%
Buffalo Small Cap Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading BUFFALO SMALL CAP GROWTH FUND
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the Buffalo Small Cap Growth Fund (“Small Cap Growth Fund” or the “Fund”) (formerly known as “Buffalo Small Cap Fund”) is 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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
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)
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 26% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 26.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
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
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Small Cap Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “small-cap growth companies.” Kornitzer Capital Management, Inc., the Fund’s investment adviser (the “Adviser” or “KCM”), defines small-cap companies as companies, at the time of purchase, with market capitalizations within the range of the Russell 2000® Growth Index. As of June 30, 2024, the range of market capitalizations of the Russell 2000® Growth Index was $17 million to $10.3 billion. KCM defines growth companies as companies that, at the time of purchase, are constituents of the Russell 3000® Growth Index or exhibit growth characteristics (generates positive cash flows or earnings that increase at faster rates than the overall economy) consistent with inclusion of companies in the Russell 3000® Growth Index. Companies included in the Fund’s investment universe must satisfy both prongs of
KCM’s definition of small-cap growth company. In addition to the Fund’s investments in domestic securities, the Fund may invest up to 20% of its net assets in sponsored or unsponsored American Depositary Receipts (“ADRs”) and securities of foreign companies that are traded on U.S. stock exchanges.

Companies are screened using in-depth, in-house research to identify those which the Adviser believes have favorable attributes, including attractive valuation, strong management, conservative debt, free cash flow, scalable business models, and competitive advantages. The Fund may invest in companies in any sector. The Fund may have significant investments in the healthcare, industrials and information technology sectors. The Adviser may sell the Fund’s investments to secure gains, limit losses, or reinvest in more promising investment opportunities.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Small Cap Growth Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities, consisting of common stocks, preferred stocks, convertible securities, warrants, and rights of “small-cap growth companies.”
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information provides some indication of the risks of investing in the Small Cap Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index. The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available on the Fund’s website at http://www.buffalofunds.com/performance.html, or by calling the Fund toll-free at 1-800-49-BUFFALO (1-800-492-8332).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provides some indication of the risks of investing in the Small Cap Growth Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one, five and ten years compare with those of a broad measure of market performance and the returns of an additional index.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-492-8332
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://www.buffalofunds.com/performance.html
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance information, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Investor Class Annual Total Return as of December 31 of Each Year
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Calendar Year-to-Date Return – Investor Class (through June 30, 2024) = -0.71%

Best and Worst Quarterly Performance (during periods shown above):
Best Quarter: June 30, 2020 = 43.88%
Worst Quarter: December 31, 2018 = -24.60%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns for the periods ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Russell 3000® Index has replaced the Russell 2000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who own the Small Cap Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are shown for Investor Class shares only and will vary for Institutional Class shares. After-tax returns are calculated using the highest historical individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on each investor’s individual tax situation and may differ from those shown in the table. The after-tax returns shown are not relevant to investors who own the Small Cap Growth Fund in a tax-deferred or other tax-advantaged arrangement, such as an individual retirement account (“IRA”) or a 401(k) plan. In certain cases, the figure representing “Return After Taxes on Distributions and Sale of Fund Shares” may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.
Buffalo Small Cap Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock If the value of the Fund’s investments decreases, the value of the Fund’s shares will also decrease and you may lose money.
Buffalo Small Cap Growth Fund | Market Risk; Recent Market Events Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Market Risk; Recent Market Events – U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent months and years due to a number of economic, political and global macro factors, including uncertainty regarding inflation and central banks’ interest rate increases, the possibility of a national or global recession, trade tensions, political events, the war between Russia and Ukraine, significant conflict between Israel and Hamas in the Middle East, and the impact of the coronavirus (COVID-19) global pandemic. These and other events may cause market disruptions and could have an adverse effect on the value of the Fund’s investments.
Buffalo Small Cap Growth Fund | Equity Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Equity Market Risk – Equity securities held by the Fund may experience sudden, unpredictable drops in value or long periods of decline in value due to general stock market fluctuations, increases in production costs, decisions by management or related factors.

Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.

Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.

Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.

Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).

Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Small Cap Growth Fund | Equity Market Risk, Common Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Common Stocks. Common stocks are susceptible to general stock market fluctuations and to volatile increases and decreases in value as market confidence in and perceptions of their issuers change. Common stock is generally subject to greater risk than preferred stocks and debt obligations because holders of common stock generally have inferior rights to receive payments from issuers in comparison with the rights of the holders of other securities, bondholders and other creditors.
Buffalo Small Cap Growth Fund | Equity Market Risk, Preferred Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Preferred Stock. Preferred stock is subject to the risk that the dividend on the stock may be changed or omitted by the issuer, and that participation in the growth of an issuer may be limited.
Buffalo Small Cap Growth Fund | Equity Market Risk, Convertible Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities. A convertible security is a fixed-income security (a debt instrument or a preferred stock) which may be converted at a stated price within a specified period of time into a certain quantity of the common stock of the same or a different issuer. The market value of a convertible security performs like that of a regular debt security, that is, if market interest rates rise, the value of the convertible security falls.
Buffalo Small Cap Growth Fund | Equity Market Risk, Warrants Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Warrants. Investments in warrants involve certain risks, including the possible lack of a liquid market for resale of the warrants, potential price fluctuations as a result of speculation or other factors, and failure of the price of the underlying security to reach or have reasonable prospects of reaching a level at which the warrant can be prudently exercised (in which event the warrant may expire without being exercised, resulting in a loss of the Fund’s entire investment therein).
Buffalo Small Cap Growth Fund | Equity Market Risk, Rights Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Rights. The purchase of rights involves the risk that the Fund could lose the purchase value of a right if the right is not exercised prior to its expiration. Also, the purchase of rights involves the risk that the effective price paid for the right added to the subscription price of the related security may exceed the value of the subscribed security’s market price.
Buffalo Small Cap Growth Fund | Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Sector Risk – Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.

Healthcare Sector Risk. To the extent the Fund invests a significant portion of its assets in the healthcare sector, the Fund will be sensitive to changes in, and its performance will depend to a greater extent on, the overall condition of the healthcare sector. Companies in the healthcare sector are subject to extensive government regulation and their profitability can be significantly affected by regulatory changes. Other risk factors include rising costs of medical products and services, pricing pressure and limited product lines, loss or impairment of intellectual property rights and litigation regarding product or service liability.

Industrials Sector Risk. Issuers in the industrials sector are affected by supply and demand, both for their specific product or service and for industrials sector products in general. The products of such issuers may face obsolescence due to rapid technological developments and frequent new product introduction. Government regulations, world events, economic conditions and exchange rates affect the performance of companies in the industrials sector. Issuers in the industrials sector may be adversely affected by liability for environmental damage, product liability claims and exchange rates. The industrials sector may also be adversely affected by changes or trends in commodity prices that may be influenced by unpredictable factors.

Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Small Cap Growth Fund | Sector Risk, Health Care Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Healthcare Sector Risk. To the extent the Fund invests a significant portion of its assets in the healthcare sector, the Fund will be sensitive to changes in, and its performance will depend to a greater extent on, the overall condition of the healthcare sector. Companies in the healthcare sector are subject to extensive government regulation and their profitability can be significantly affected by regulatory changes. Other risk factors include rising costs of medical products and services, pricing pressure and limited product lines, loss or impairment of intellectual property rights and litigation regarding product or service liability.
Buffalo Small Cap Growth Fund | Sector Risk, Industrials Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Industrials Sector Risk. Issuers in the industrials sector are affected by supply and demand, both for their specific product or service and for industrials sector products in general. The products of such issuers may face obsolescence due to rapid technological developments and frequent new product introduction. Government regulations, world events, economic conditions and exchange rates affect the performance of companies in the industrials sector. Issuers in the industrials sector may be adversely affected by liability for environmental damage, product liability claims and exchange rates. The industrials sector may also be adversely affected by changes or trends in commodity prices that may be influenced by unpredictable factors.
Buffalo Small Cap Growth Fund | Sector Risk, Information Technology Sector Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Information Technology Sector Risk. Information technology companies often face unusually high price volatility, both in terms of gains and losses. The potential for wide variations in performance is based on special risks common to information technology companies. Information technology companies may have limited product lines, markets or financial resources. Information technology companies are affected by worldwide technological developments and their products and services may quickly become outdated. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to withstand the Fund’s potential for volatility.
Buffalo Small Cap Growth Fund | Growth-Style Investing Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Growth-Style Investing Risks – Because the Fund focuses on growth-style stocks, its performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a different investment style, such as value-style stocks. Growth stocks are often characterized by high price-to-earnings ratios and as a result, may be more volatile than stocks with lower price-to-earnings ratios.
Buffalo Small Cap Growth Fund | Management Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Management Risk – Management risk means that your investment in the Fund varies with the success and failure of the Adviser’s investment strategies and the Adviser’s research, analysis and determination of portfolio securities.
Buffalo Small Cap Growth Fund | Micro-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Micro-Cap Company Risk – Investing in micro-cap companies may involve greater risk than investing in companies with larger capitalization due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than companies with larger capitalization. In addition, micro-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans. The trading volume of securities of smaller capitalization companies is normally less than that of larger capitalization companies, and therefore may disproportionately affect their market price, tending to make them fall more in response to selling pressure than is the case with larger capitalization companies. These risks are enhanced for micro-cap securities. Many micro-cap companies tend to be new and have no proven track record. Some of these companies have no assets or operations, while others have products and services that are still in development or have yet to be tested in the market. As any size of trade can have a large percentage impact on the price of a micro-cap stock, the Fund will be more susceptible to sudden and significant losses. In addition, micro-cap company stocks will also be
bought and sold less often than other stocks, making them less liquid than other securities. Because of this, if the Fund wants to sell a large quantity of a micro-cap company’s stock, it may have to sell at a lower price than the Adviser might prefer, or it may have to sell in smaller than desired quantities over a period of time. Given these risks, an investment in the Fund may be more suitable for long-term investors who are willing to bear the risk of these fluctuations.
Buffalo Small Cap Growth Fund | Mid-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Mid-Cap Company Risk – Investing in mid-cap companies may involve greater risk than investing in large-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than large-cap companies. In addition, mid-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Small Cap Growth Fund | Small-Cap Company Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Small-Cap Company Risk – Investing in small-cap companies may involve greater risk than investing in large- or mid-cap companies due to less management experience, fewer financial resources, less product diversification and fewer competitive strengths. Therefore, such securities may be more volatile and less liquid than mid- and large-cap companies. In addition, small-cap companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.
Buffalo Small Cap Growth Fund | Money Market Funds Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Money Market Funds Risk – An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for the Fund to lose money if shares of money market funds in which it invests fall below $1.00 per share.
Buffalo Small Cap Growth Fund | Foreign Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Foreign Risk – Investing in securities of foreign corporations involves additional risks relating to: political, social, religious and economic developments abroad; market instability; fluctuations in foreign exchange rates; different regulatory requirements, market practices, accounting standards and practices; and less publicly available information about foreign issuers. Additionally, these investments may be subject to foreign withholding taxes, may be less liquid, carry higher brokerage commissions and other fees, and procedures and regulations governing transactions and custody in foreign markets also may involve delays in payment, delivery or recovery of money or investments. Investments in common stocks of U.S. companies with international operations, and the purchase of sponsored or unsponsored ADRs carry similar risks.

American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Small Cap Growth Fund | Foreign Risk, American Depositary Receipts Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
American Depositary Receipts. Unsponsored ADRs held by the Fund are frequently under no obligation to distribute shareholder communications received from the underlying issuer. For this and other reasons, there is less information available about unsponsored ADRs than sponsored ADRs. Unsponsored ADRs are also not obligated to pass through voting rights to the Fund. Investing in foreign companies, even indirectly through ADRs, may involve the same inherent risks as investing in securities of foreign issuers, as described above.
Buffalo Small Cap Growth Fund | Cybersecurity Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk – With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security, and related risks. Cyber incidents affecting the Fund or its service providers may cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its NAV, impediments to trading, the inability of shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, or additional compliance costs.
Buffalo Small Cap Growth Fund | Russell 2000® Growth Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 2000® Growth Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 18.66%
5 Years rr_AverageAnnualReturnYear05 9.22%
10 Years rr_AverageAnnualReturnYear10 7.16%
Buffalo Small Cap Growth Fund | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index*(reflects no deduction for fees, expenses or taxes) [20]
1 Year rr_AverageAnnualReturnYear01 25.96% [20]
5 Years rr_AverageAnnualReturnYear05 15.16% [20]
10 Years rr_AverageAnnualReturnYear10 11.48% [20]
Buffalo Small Cap Growth Fund | Investor Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUFSX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets 0.10% [21]
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.97% [22]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 99
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 309
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 536
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,190
Annual Return 2014 rr_AnnualReturn2014 (6.55%)
Annual Return 2015 rr_AnnualReturn2015 (4.46%)
Annual Return 2016 rr_AnnualReturn2016 6.22%
Annual Return 2017 rr_AnnualReturn2017 27.07%
Annual Return 2018 rr_AnnualReturn2018 (5.78%)
Annual Return 2019 rr_AnnualReturn2019 40.97%
Annual Return 2020 rr_AnnualReturn2020 66.36%
Annual Return 2021 rr_AnnualReturn2021 4.85%
Annual Return 2022 rr_AnnualReturn2022 (30.01%)
Annual Return 2023 rr_AnnualReturn2023 5.45%
Year to Date Return, Label rr_YearToDateReturnLabel Calendar Year-to-Date Return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (0.71%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 43.88%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.60%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 5.45%
5 Years rr_AverageAnnualReturnYear05 12.66%
10 Years rr_AverageAnnualReturnYear10 7.50%
Buffalo Small Cap Growth Fund | Investor Class | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 5.45%
5 Years rr_AverageAnnualReturnYear05 10.74%
10 Years rr_AverageAnnualReturnYear10 3.50%
Buffalo Small Cap Growth Fund | Investor Class | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 3.23%
5 Years rr_AverageAnnualReturnYear05 9.93%
10 Years rr_AverageAnnualReturnYear10 4.73%
Buffalo Small Cap Growth Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol BUISX
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.85%
Shareholder Servicing Fee rr_Component1OtherExpensesOverAssets none
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87% [22]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 482
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,073
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 5.57%
5 Years rr_AverageAnnualReturnYear05 12.82%
10 Years rr_AverageAnnualReturnYear10 7.65%
[1] The Russell 3000® Index has replaced the Russell Midcap® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[2] The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
[3] The Russell 3000® Index has replaced the Russell 1000® Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[4] The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
[5] The Russell 3000® Index has replaced the Russell 2000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[6] Investor Class shares are subject to an annual shareholder servicing fee of up to 0.15% pursuant to the Fund’s Shareholder Servicing Plan. The maximum rate of the shareholder servicing fee may not be incurred in a given year.
[7] The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
[8] The Russell 3000® Index has replaced the Russell 3000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[9] Investor Class shares are subject to an annual shareholder servicing fee of up to 0.15% pursuant to the Fund’s Shareholder Servicing Plan. The maximum rate of the shareholder servicing fee may not be incurred in a given year.
[10] The Bloomberg Universal Bond Index has replaced the ICE BofA US High Yield® Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[11] The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
[12] The FTSE Global All Cap ex US Index has replaced the FTSE All-World ex US Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[13] Acquired Fund Fees and Expenses represent the indirect costs of the Fund’s investments in other investment companies.
[14] The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
[15] The Russell 3000® Index has replaced the Russell 1000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[16] Investor Class shares are subject to an annual shareholder servicing fee of up to 0.15% pursuant to the Fund’s Shareholder Servicing Plan. The maximum rate of the shareholder servicing fee may not be incurred in a given year.
[17] The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.
[18] The Russell 3000® Index has replaced the Russell Midcap® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an
“appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[19] Investor Class shares are subject to an annual shareholder servicing fee of up to 0.15% pursuant to the Fund’s Shareholder Servicing Plan. The maximum rate of the shareholder servicing fee may not be incurred in a given year.
[20] The Russell 3000® Index has replaced the Russell 2000® Growth Index as the Fund’s primary benchmark. The change of primary benchmark was the result of SEC rule amendments that require funds to show their performance against an “appropriate broad-based securities market index” that reflects the overall applicable market in which a fund invests. The Adviser believes the secondary benchmark is a more appropriate performance comparison given the Fund’s holdings.
[21] Investor Class shares are subject to an annual shareholder servicing fee of up to 0.15% pursuant to the Fund’s Shareholder Servicing Plan. The maximum rate of the shareholder servicing fee may not be incurred in a given year.
[22] The Total Annual Fund Operating Expenses for each Class of the Fund do not correlate to the ratio of expenses to average net assets listed in the Fund’s financial highlights, which reflects the operating expenses of each Class of the Fund and does not include the amount of the Fund’s proportionate share of the fees and expenses of other investment companies in which each Class of the Fund invests.