Risk/Return Detail Data - FidelityGrowthStrategiesFund-AMCIZPRO |
Jan. 29, 2025
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| Risk/Return: | ||||||||||
| Registrant Name | Fidelity Mt. Vernon Street Trust | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | ||||||||||
| Risk/Return: | ||||||||||
| Risk/Return [Heading] | Fund Summary Fund /Class: Fidelity® Growth Strategies Fund /Fidelity Advisor® Growth Strategies Fund A, M, C, I, Z | |||||||||
| Objective [Heading] | Investment Objective | |||||||||
| Objective, Primary [Text Block] | Fidelity® Growth Strategies Fund seeks capital appreciation. | |||||||||
| Expense [Heading] | Fee Table | |||||||||
| Expense Narrative [Text Block] | The following table describes the fees and expenses that may be incurred when 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 examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $ 50,000 in the fund or certain other Fidelity ® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 32 of the prospectus and in the sales charge waiver appendix to the prospectus. | |||||||||
| Shareholder Fees Caption [Text] | Shareholder fees | |||||||||
| Operating Expenses Caption [Text] | Annual Operating Expenses | |||||||||
| Portfolio Turnover [Heading] | Portfolio Turnover | |||||||||
| Portfolio Turnover [Text Block] | 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 operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 93 % of the average value of its portfolio. | |||||||||
| Portfolio Turnover, Rate | 93.00% | |||||||||
| Expenses Deferred Charges [Text Block] | Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% and 0.25%, respectively. | |||||||||
| Expense Breakpoint Discounts [Text] | You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $ 50,000 in the fund or certain other Fidelity ® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 32 of the prospectus | |||||||||
| Expense Breakpoint, Minimum Investment Required [Amount] | $ 50,000 | |||||||||
| Other Expenses, New Fund, Based on Estimates [Text] | Based on estimated amounts for the current fiscal year. | |||||||||
| Expense Example Narrative [Text Block] | This example helps compare the cost of investing in the fund with the cost of investing in other funds. Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares: | |||||||||
| Strategy [Heading] | Principal Investment Strategies | |||||||||
| Strategy Narrative [Text Block] | Normally investing primarily in common stocks. Normally investing in companies that Fidelity Management & Research Company LLC (FMR) believes offer the potential for accelerated earnings or revenue growth (stocks of these companies are often called "growth" stocks). Focusing investments in medium-sized companies, but may also invest substantially in larger or smaller companies. Investing in domestic and foreign issuers. Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments. Effective December 11, 2025, normally investing at least 80% of assets in securities of growth companies. Growth companies are companies the Adviser believes have above average growth potential. The Adviser considers a number of factors in determining a company's growth potential, such as whether the company is included in a third-party growth benchmark or classified as a growth company by a third-party vendor, if the company's projected earnings per share growth, sales growth per share or free cash flow growth or its trailing earnings per share growth is above the equity market median, if the company's research and development expenses exceed sales, general and administrative expenses, or if the company is raising capital to grow, fund or expand its business. A company's growth potential can be determined under any of these factors. Derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives. | |||||||||
| Risk [Heading] | Principal Investment Risks | |||||||||
| Bar Chart and Performance Table [Heading] | Performance | |||||||||
| Performance Narrative [Text Block] | The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of Fidelity® Growth Strategies Fund, a class of shares of the fund, from year to year and compares the performance of this class to the performance of a securities market index and an additional index over various periods of time. The additional index has characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance. Visit www.fidelity.com for more recent performance information for Fidelity® Growth Strategies Fund, a class of shares of the fund . Performance history will be available at institutional.fidelity.com for Class A, Class M, Class C, Class I, and Class Z after Class A, Class M, Class C, Class I, and Class Z have been in operation for one calendar year. | |||||||||
| Performance Information Illustrates Variability of Returns [Text] | The information illustrates the changes in the performance of Fidelity® Growth Strategies Fund, a class of shares of the fund, from year to year and compares the performance of this class to the performance of a securities market index and an additional index over various periods of time. | |||||||||
| Performance One Year or Less [Text] | Performance history will be available at institutional.fidelity.com for Class A, Class M, Class C, Class I, and Class Z after Class A, Class M, Class C, Class I, and Class Z have been in operation for one calendar year. | |||||||||
| Performance Availability Website Address [Text] | www.fidelity.com | |||||||||
| Performance Past Does Not Indicate Future [Text] | Past performance (before and after taxes) is not an indication of future performance. | |||||||||
| Bar Chart [Heading] | Year-by-Year Returns | |||||||||
| Highest Quarterly Return, Label | Highest Quarter Return | |||||||||
| Highest Quarterly Return, Date | Jun. 30, 2020 | |||||||||
| Highest Quarterly Return | 25.82% | |||||||||
| Lowest Quarterly Return, Label | Lowest Quarter Return | |||||||||
| Lowest Quarterly Return, Date | Jun. 30, 2022 | |||||||||
| Lowest Quarterly Return | (19.41%) | |||||||||
| Performance Table Heading | Average Annual Returns | |||||||||
| Performance Table Uses Highest Federal Rate | After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. | |||||||||
| Performance Table Not Relevant to Tax Deferred | The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). | |||||||||
| Performance Table Explanation after Tax Higher | Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares. | |||||||||
| Performance Table Narrative | After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares. | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | Fidelity Advisor Growth Strategies Fund - Class C | ||||||||||
| Risk/Return: | ||||||||||
| Maximum sales charge (load) on purchases (as a % of offering price) | none | |||||||||
| Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds) | 1.00% | [1] | ||||||||
| Management fee | 0.72% | [2],[3] | ||||||||
| Distribution and/or Service (12b-1) fees | 1.00% | |||||||||
| Other expenses | 0.01% | [3] | ||||||||
| Total annual operating expenses | 1.73% | |||||||||
| Expenses Deferred Charges [Text Block] | On Class C shares redeemed less than one year after purchase. | |||||||||
| 1 year | $ 276 | |||||||||
| 3 years | 545 | |||||||||
| 5 years | 939 | |||||||||
| 10 years | 1,842 | |||||||||
| 1 Year | 176 | |||||||||
| 3 Years | 545 | |||||||||
| 5 Years | 939 | |||||||||
| 10 Years | $ 1,842 | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | Fidelity Advisor Growth Strategies Fund - Class M | ||||||||||
| Risk/Return: | ||||||||||
| Maximum sales charge (load) on purchases (as a % of offering price) | 3.50% | |||||||||
| Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds) | none | [4] | ||||||||
| Management fee | 0.72% | [2],[3] | ||||||||
| Distribution and/or Service (12b-1) fees | 0.50% | |||||||||
| Other expenses | 0.01% | [3] | ||||||||
| Total annual operating expenses | 1.23% | |||||||||
| 1 year | $ 471 | |||||||||
| 3 years | 727 | |||||||||
| 5 years | 1,002 | |||||||||
| 10 years | 1,787 | |||||||||
| 1 Year | 471 | |||||||||
| 3 Years | 727 | |||||||||
| 5 Years | 1,002 | |||||||||
| 10 Years | $ 1,787 | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | Fidelity Advisor Growth Strategies Fund - Class I | ||||||||||
| Risk/Return: | ||||||||||
| Maximum sales charge (load) on purchases (as a % of offering price) | none | |||||||||
| Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds) | none | |||||||||
| Management fee | 0.72% | [2],[3] | ||||||||
| Distribution and/or Service (12b-1) fees | none | |||||||||
| Other expenses | 0.01% | [3] | ||||||||
| Total annual operating expenses | 0.73% | |||||||||
| 1 year | $ 75 | |||||||||
| 3 years | 233 | |||||||||
| 5 years | 406 | |||||||||
| 10 years | 906 | |||||||||
| 1 Year | 75 | |||||||||
| 3 Years | 233 | |||||||||
| 5 Years | 406 | |||||||||
| 10 Years | $ 906 | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | Fidelity Advisor Growth Strategies Fund - Class Z | ||||||||||
| Risk/Return: | ||||||||||
| Maximum sales charge (load) on purchases (as a % of offering price) | none | |||||||||
| Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds) | none | |||||||||
| Management fee | 0.60% | [2],[3] | ||||||||
| Distribution and/or Service (12b-1) fees | none | |||||||||
| Other expenses | 0.01% | [3] | ||||||||
| Total annual operating expenses | 0.61% | |||||||||
| 1 year | $ 62 | |||||||||
| 3 years | 195 | |||||||||
| 5 years | 340 | |||||||||
| 10 years | 762 | |||||||||
| 1 Year | 62 | |||||||||
| 3 Years | 195 | |||||||||
| 5 Years | 340 | |||||||||
| 10 Years | $ 762 | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | Fidelity Advisor Growth Strategies Fund - Class A | ||||||||||
| Risk/Return: | ||||||||||
| Maximum sales charge (load) on purchases (as a % of offering price) | 5.75% | |||||||||
| Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds) | none | [4] | ||||||||
| Management fee | 0.72% | [2],[3] | ||||||||
| Distribution and/or Service (12b-1) fees | 0.25% | |||||||||
| Other expenses | 0.01% | [3] | ||||||||
| Total annual operating expenses | 0.98% | |||||||||
| 1 year | $ 669 | |||||||||
| 3 years | 869 | |||||||||
| 5 years | 1,086 | |||||||||
| 10 years | 1,707 | |||||||||
| 1 Year | 669 | |||||||||
| 3 Years | 869 | |||||||||
| 5 Years | 1,086 | |||||||||
| 10 Years | $ 1,707 | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | RS012 | ||||||||||
| Risk/Return: | ||||||||||
| Label | Russell Midcap® Growth Index | |||||||||
| Past 1 year | 22.10% | |||||||||
| Past 5 years | 11.47% | |||||||||
| Past 10 years | 11.54% | |||||||||
| FidelityGrowthStrategiesFund-AMCIZPRO | Fidelity Growth Strategies Fund | RS003 | ||||||||||
| Risk/Return: | ||||||||||
| Label | Russell 3000® Index | |||||||||
| Past 1 year | 23.81% | |||||||||
| Past 5 years | 13.86% | |||||||||
| Past 10 years | 12.55% | |||||||||
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