FAM Value Fund | Investor Class

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Registrant Name

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FENIMORE ASSET MANAGEMENT TRUST

Prospectus Date

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May 01, 2015

Maximum sales charge (load) on purchase

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none

Maximum deferred sales charge (load)

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none

Redemption fee

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none

Management Fees

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1.00%

Distribution and Service (12b-1) Fees

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none

Other Expenses

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0.18%

Total Annual Fund Operating Expenses

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1.18%

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120

3 Years

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375

rr_ExpenseExampleYear05

649

Highest Quarterly Return, Label

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Best Quarter

Highest Quarterly Return, Date

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Dec. 31, 2011

Highest Quarterly Return

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13.34%

Lowest Quarterly Return, Label

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Worst Quarter

Lowest Quarterly Return, Date

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Dec. 31, 2008

Lowest Quarterly Return

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(20.68%)

rr_AverageAnnualReturnYear01

13.41%

rr_AverageAnnualReturnYear05

14.38%

FAM Value Fund | Investor Class | after taxes on distributions

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6.86%

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rr_AverageAnnualReturnYear01

12.27%

rr_AverageAnnualReturnYear05

13.75%

FAM Value Fund | Investor Class | after taxes on distributions and sale of fund shares

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6.24%

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rr_AverageAnnualReturnYear01

9.32%

rr_AverageAnnualReturnYear05

11.99%

rr_AverageAnnualReturnYear10

5.63%

FAM Value Fund

Objective, Primary [Text Block]

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Risk/Return [Heading]

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FAM Value Fund

Objective [Heading]

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Investment Objective:

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FAM Value Fund's investment objective is to maximize long-term return on capital.

Expense [Heading]

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Fees and Expenses of the Fund:

Expense Narrative [Text Block]

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The tables below describe the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

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S H A R E H O L D E R F E E S

(fees paid directly from your investment)

Operating Expenses Caption [Text]

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AN N UA L F U N D O P E R AT I N G E X P E N S E S

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

Portfolio Turnover [Heading]

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Portfolio Turnover:

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 6.08% of the average value of its portfolio.

Portfolio Turnover, Rate

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6.08%

Expense Example [Heading]

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Expense Example:

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example by, Year, Caption [Text]

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EXPENSE EXAMPLE

Strategy [Heading]

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Principal Investment Strategies:

Strategy Narrative [Text Block]

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Fenimore Asset Management, Inc. ("Fenimore"), the investment advisor to the Fund, employs a "value approach" in making its common stock selections. This approach is based on Fenimore's belief that at any given point in time the stock price of a company may sell below the company's "true business worth". Factors considered in evaluating the true business worth include the company's current earnings and Fenimore's opinion as to its future earnings potential. After identifying a company whose securities are determined to have a favorable price-to-earnings relationship, Fenimore plans to invest in such securities until the "true business worth" nears the market price of the company's securities.

Generally, the Fund will attempt to remain fully invested in common stocks and securities that are convertible into common stocks, such as convertible bonds and convertible preferred stocks. The Fund may invest in the securities of issuers of all sizes and market capitalizations. The Fund may also invest in the securities of both domestic and foreign issuers and it may invest in shares of other investment companies, including exchange-traded funds ("ETFs").

Risk [Heading]

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Principal Risks:

Risk Narrative [Text Block]

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• Stock Market Risk- the value of stocks fluctuate in response to the activities of individual companies and general stock market and economic conditions. Stock prices may decline over short or extended periods of time. Stocks are more volatile and riskier than some other forms of investments.

• Stock Selection Risk - the value stocks chosen for the Fund are subject to the risk that the market may never realize their intrinsic value or their prices may go down.

• Small-Cap Risk - small capitalization companies may not have the size, resources or other assets of large capitalization companies.

• Market Risk - the value of your investment will go up and down, which means that you could lose money.

• Foreign Investment Risk - the Fund may invest in securities of foreign issuers that are traded in foreign markets or may be represented by American Depository Receipts that are traded in the United States. Investments in non-U.S. securities may involve additional risk including exchange rate fluctuation, political or economic instability, the imposition of exchange controls, expropriation, limited disclosure and illiquid markets.

• Investment in Other Investment Companies Risk - the Fund may invest in shares of other investment companies, including ETFs. Shareholders of the Fund will indirectly be subject to the fees and expenses of the other investment companies in which the Fund invests. In addition, shareholders will be exposed to the investment risks associated with investments in other investment companies.

Risk Lose Money [Text]

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the value of your investment will go up and down, which means that you could lose money.

Bar Chart and Performance Table [Heading]

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Annual Total Return:

Performance Narrative [Text Block]

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The following bar chart and table show some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund's performance since 2005. The table shows the Fund's average annual returns (before and after taxes ) for the one year, five year and ten year periods compared to those of the Russell MidCap Index, the Fund's primary benchmark index. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance information may be obtained at the Fund's website famfunds.com.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart shows changes in the Fund's performance since 2005. The table shows the Fund's average annual returns (before and after taxes ) for the one year, five year and ten year periods compared to those of the Russell MidCap Index, the Fund's primary benchmark index.

Performance Availability Website Address [Text]

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famfunds.com

Performance Past Does Not Indicate Future [Text]

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

Bar Chart Closing [Text Block]

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Best Quarter (ended 12/31/11):

13.34%

Worst Quarter (ended 12/31/08):

-20.68%

Performance Table Heading

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A V E R A G E A N N U A L T O T A L R E T U R N

(for the periods ending December 31, 2014)

Performance Table Uses Highest Federal Rate

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The after-tax returns shown in the table are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts, or to investors who are tax exempt.

Performance Table Narrative

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The after-tax returns shown in the table are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts, or to investors who are tax exempt.

FAM Value Fund | Russell Mid-Cap index

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rr_AverageAnnualReturnYear01

13.22%

rr_AverageAnnualReturnYear05

17.19%