Risk/Return Detail Data - FidelityMidCapValueK6Fund-PRO	Apr. 01, 2025 USD ($)
Risk/Return:
Registrant Name	Fidelity Devonshire Trust
FidelityMidCapValueK6Fund-PRO | Fidelity Mid Cap Value K6 Fund
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund: Fidelity® Mid Cap Value K6 Fund
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity® Mid Cap Value K6 Fund seeks long-term growth of capital.
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, which are not reflected in the tables and examples below.
Shareholder Fees Caption [Text]	Shareholder fees
(fees paid directly from your investment)	none
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 140 % of the average value of its portfolio.
Portfolio Turnover, Rate	140.00%
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:
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Normally investing primarily in common stocks. Normally investing at least 80% of assets in securities of companies with medium market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell Midcap® Index or the S&P MidCap 400® Index). Potentially investing in companies with smaller or larger market capitalizations. Investing in securities of companies that Fidelity Management & Research Company LLC (FMR) believes are undervalued in the marketplace in relation to factors such as assets, sales, earnings, growth potential, or cash flow, or in relation to securities of other companies in the same industry (stocks of these companies are often called "value" stocks). 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 value companies with medium market capitalizations. The Adviser generally defines medium market capitalization companies as those whose market capitalization is similar to the market capitalization of companies in the Russell Midcap ® Index or the S&P MidCap 400 ® Index. Value companies are companies the Adviser believes are undervalued in the marketplace. The Adviser considers traditional and other measures of value, such as whether the company is included in a third-party value benchmark or classified as a value company by a third-party vendor, whether the company's free cash flow yield is above the equity market median, whether the company's enterprise value (the total value of a company's outstanding equity and debt) relative to earnings is below the equity market median, or whether the company's price-to-book (P/B) ratio or projected price-to-earnings (P/E) ratio is below the equity market median. An issuer may be determined to be a value company 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 the fund's shares from year to year and compares the performance of the fund's shares 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 is not an indication of future performance. Visit www.401k.com and log in for more recent performance information.
Performance Information Illustrates Variability of Returns [Text]	The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.
Performance Availability Website Address [Text]	www.401k.com
Performance Past Does Not Indicate Future [Text]	Past performance 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	Dec. 31, 2020
Highest Quarterly Return	21.11%
Lowest Quarterly Return, Label	Lowest Quarter Return
Lowest Quarterly Return, Date	Mar. 31, 2020
Lowest Quarterly Return	(32.06%)
Performance Table Heading	Average Annual Returns
FidelityMidCapValueK6Fund-PRO | Fidelity Mid Cap Value K6 Fund | Fidelity Mid Cap Value K6 Fund
Risk/Return:
Management fee	0.45%
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	0.45%
1 year	$ 46
3 years	144
5 years	252
10 years	$ 567
Annual Return, Inception Date	May 25, 2017
2018	(18.66%)
2019	23.66%
2020	0.54%
2021	34.12%
2022	(10.25%)
2023	23.09%
2024	13.79%
FidelityMidCapValueK6Fund-PRO | Fidelity Mid Cap Value K6 Fund | Return Before Taxes | Fidelity Mid Cap Value K6 Fund
Risk/Return:
Label	Fidelity® Mid Cap Value K6 Fund
Past 1 year	13.79%
Past 5 years	11.13%
Since Inception	8.96%	[1]
FidelityMidCapValueK6Fund-PRO | Fidelity Mid Cap Value K6 Fund | RS013
Risk/Return:
Label	Russell Midcap® Value Index
Past 1 year	13.07%
Past 5 years	8.59%
Since Inception	8.30%
FidelityMidCapValueK6Fund-PRO | Fidelity Mid Cap Value K6 Fund | RS003
Risk/Return:
Label	Russell 3000® Index
Past 1 year	23.81%
Past 5 years	13.86%
Since Inception	13.73%

[1] A From May 25, 2017 .