Risk/Return Detail Data - FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO	Apr. 29, 2024 USD ($)
Risk/Return:
Registrant Name	Fidelity Select Portfolios
FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO | Fidelity Environment and Alternative Energy Fund
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund: Fidelity® Environment and Alternative Energy Fund
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity® Environment and Alternative Energy 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. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of the fund, which are not reflected in the table and example 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 35 % of the average value of its portfolio.
Portfolio Turnover, Rate	35.00%
Expenses Restated to Reflect Current [Text]	Adjusted to reflect current fees.
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 principally engaged in business activities related to alternative and renewable energy, energy efficiency, pollution control, water infrastructure, waste and recycling technologies, or other environmental support services. 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. Employing sustainable investing exclusion criteria to avoid investments in issuers that are directly engaged in, and/or derive significant revenue from, certain industries. Please see "Fund Basics - Investment Details - Sustainable Investing Exclusions" for additional information.
Strategy Portfolio Concentration [Text]	Normally investing at least 80% of assets in securities of companies principally engaged in business activities related to alternative and renewable energy, energy efficiency, pollution control, water infrastructure, waste and recycling technologies, or other environmental support services.
Risk [Heading]	Principal Investment Risks
Risk Narrative [Text Block]	Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. Sustainability Risk. Application of Fidelity Management & Research Company LLC's (FMR) (the Adviser) environmental, social and governance (ESG) ratings process and/or its sustainable investing exclusion criteria may affect the fund's exposure to certain issuers, sectors, regions, and countries and may affect the fund's performance depending on whether certain investments are in or out of favor. The criteria related to the fund's ESG ratings process and/or adherence to its sustainable investing exclusion criteria may result in the fund forgoing opportunities to buy certain securities when it might otherwise be advantageous to do so, or selling securities for ESG reasons when it might be otherwise disadvantageous for it to do so. As a result, the fund's performance may at times be better or worse than the performance of funds that do not use ESG or sustainability criteria. There are significant differences in interpretations of what it means for an issuer to have positive ESG factors. While the Adviser believes its definitions are reasonable, the portfolio decisions it makes may differ with other investors' or advisers' views. When evaluating an issuer, the Adviser is dependent on information or data obtained through voluntary or third-party reporting that may be incomplete, inaccurate, or unavailable, which could cause the Adviser to incorrectly assess an issuer's business practices. Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. Environment and Alternative Energy Industry Concentration. The environment and alternative energy industries can be significantly affected by government regulations and subsidies, changing supply and demand for traditional energy sources, and availability of funding for remedial cleanup or development of new technologies, and can be subject to risks associated with hazardous materials. Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. The value of securities of smaller issuers can be more volatile than that of larger issuers. In addition, the fund is classified as non-diversified under the Investment Company Act of 1940 (1940 Act), which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund. An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency .   You could lose money by investing in the fund.
Risk Lose Money [Text]	You could lose money by investing in the fund.
Risk Nondiversified Status [Text]	In addition, the fund is classified as non-diversified under the Investment Company Act of 1940 (1940 Act), which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.
Risk Not Insured Depository Institution [Text]	An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency .
Bar Chart and Performance Table [Heading]	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 indexes have 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.
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.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
Year to Date Return, Label	Year-to-Date Return
Bar Chart, Year to Date Return, Date	Mar. 31, 2024
Bar Chart, Year to Date Return	7.55%
Highest Quarterly Return, Label	Highest Quarter Return
Highest Quarterly Return, Date	Dec. 31, 2020
Highest Quarterly Return	22.72%
Lowest Quarterly Return, Label	Lowest Quarter Return
Lowest Quarterly Return, Date	Mar. 31, 2020
Lowest Quarterly Return	(26.22%)
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.
FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO | Fidelity Environment and Alternative Energy Fund | Fidelity Environment and Alternative Energy Fund
Risk/Return:
Management fee	0.69%	[1],[2]
Distribution and/or Service (12b-1) fees	none
Other expenses	0.02%	[2]
Total annual operating expenses	0.71%
1 year	$ 73
3 years	227
5 years	395
10 years	$ 883
2014	1.86%
2015	(4.59%)
2016	20.72%
2017	25.25%
2018	(13.43%)
2019	26.83%
2020	21.18%
2021	30.42%
2022	(26.04%)
2023	26.29%
FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO | Fidelity Environment and Alternative Energy Fund | Return Before Taxes | Fidelity Environment and Alternative Energy Fund
Risk/Return:
Label	Return Before Taxes
Past 1 year	26.29%
Past 5 years	13.36%
Past 10 years	9.07%
FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO | Fidelity Environment and Alternative Energy Fund | After Taxes on Distributions | Fidelity Environment and Alternative Energy Fund
Risk/Return:
Label	Return After Taxes on Distributions
Past 1 year	26.17%
Past 5 years	12.24%
Past 10 years	7.76%
FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO | Fidelity Environment and Alternative Energy Fund | After Taxes on Distributions and Sales | Fidelity Environment and Alternative Energy Fund
Risk/Return:
Label	Return After Taxes on Distributions and Sale of Fund Shares
Past 1 year	15.65%
Past 5 years	10.46%
Past 10 years	6.98%
FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO | Fidelity Environment and Alternative Energy Fund | SP001
Risk/Return:
Label	S&P 500® Index
Past 1 year	26.29%
Past 5 years	15.69%
Past 10 years	12.03%
FidelityEnvironmentandAlternativeEnergyNaturalResourcesFunds-ComboPRO | Fidelity Environment and Alternative Energy Fund | FT128
Risk/Return:
Label	FTSE® Environmental Opportunities & Alternative Energy Index
Past 1 year	26.65%
Past 5 years	20.13%
Past 10 years	13.12%

[1] A The management fee covers administrative services previously provided under separate services agreements with the fund, for which 0.23% was previously charged under the services agreements.

[2] B Adjusted to reflect current fees.