v3.25.3
Risk/Return Detail Data - SelectTechnologyPortfolio-AMCIZPro - USD ($)
 12 Months Ended 60 Months Ended 120 Months Ended
Oct. 31, 2025
Oct. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Oct. 31, 2025
Oct. 31, 2025
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | Fidelity Advisor Energy Fund - Class A                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 5.75%                          
Maximum Deferred Sales Charge (as a percentage) [1] 0.00%                          
Management Fees (as a percentage of Assets) [2] 0.67%                          
Distribution and Service (12b-1) Fees 0.25%                          
Other Expenses (as a percentage of Assets): [2] 0.02%                          
Expenses (as a percentage of Assets) 0.94%                          
Expense Example, with Redemption, 1 Year $ 665                          
Expense Example, with Redemption, 3 Years 857                          
Expense Example, with Redemption, 5 Years 1,065                          
Expense Example, with Redemption, 10 Years 1,663                          
Expense Example, No Redemption, 1 Year 665                          
Expense Example, No Redemption, 3 Years 857                          
Expense Example, No Redemption, 5 Years 1,065                          
Expense Example, No Redemption, 10 Years $ 1,663                          
Average Annual Return, Label [Optional Text]   Return Before Taxes                        
Average Annual Return, Percent   4.26%                     12.46% 4.39%
Annual Return [Percent]     4.26% 0.93% 63.03% 55.35% (32.51%) 9.88% (24.92%) (2.64%) 33.84% (20.53%)    
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | Fidelity Advisor Energy Fund - Class M                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 3.50%                          
Maximum Deferred Sales Charge (as a percentage) [1] 0.00%                          
Management Fees (as a percentage of Assets) [2] 0.67%                          
Distribution and Service (12b-1) Fees 0.50%                          
Other Expenses (as a percentage of Assets): [2] 0.02%                          
Expenses (as a percentage of Assets) 1.19%                          
Expense Example, with Redemption, 1 Year $ 467                          
Expense Example, with Redemption, 3 Years 715                          
Expense Example, with Redemption, 5 Years 981                          
Expense Example, with Redemption, 10 Years 1,743                          
Expense Example, No Redemption, 1 Year 467                          
Expense Example, No Redemption, 3 Years 715                          
Expense Example, No Redemption, 5 Years 981                          
Expense Example, No Redemption, 10 Years $ 1,743                          
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | Fidelity Advisor Energy Fund - Class C                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) [3] 1.00%                          
Management Fees (as a percentage of Assets) [2] 0.67%                          
Distribution and Service (12b-1) Fees 1.00%                          
Other Expenses (as a percentage of Assets): [2] 0.02%                          
Expenses (as a percentage of Assets) 1.69%                          
Expenses Deferred Charges [Text Block] On Class C shares redeemed less than one year after purchase.                          
Expense Example, with Redemption, 1 Year $ 272                          
Expense Example, with Redemption, 3 Years 533                          
Expense Example, with Redemption, 5 Years 918                          
Expense Example, with Redemption, 10 Years 1,799                          
Expense Example, No Redemption, 1 Year 172                          
Expense Example, No Redemption, 3 Years 533                          
Expense Example, No Redemption, 5 Years 918                          
Expense Example, No Redemption, 10 Years $ 1,799                          
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | Fidelity Advisor Energy Fund - Class I                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) 0.00%                          
Management Fees (as a percentage of Assets) [2] 0.67%                          
Distribution and Service (12b-1) Fees 0.00%                          
Other Expenses (as a percentage of Assets): [2] 0.02%                          
Expenses (as a percentage of Assets) 0.69%                          
Expense Example, with Redemption, 1 Year $ 70                          
Expense Example, with Redemption, 3 Years 221                          
Expense Example, with Redemption, 5 Years 384                          
Expense Example, with Redemption, 10 Years 859                          
Expense Example, No Redemption, 1 Year 70                          
Expense Example, No Redemption, 3 Years 221                          
Expense Example, No Redemption, 5 Years 384                          
Expense Example, No Redemption, 10 Years $ 859                          
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | Fidelity Advisor Energy Fund - Class Z                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) 0.00%                          
Management Fees (as a percentage of Assets) [2] 0.55%                          
Distribution and Service (12b-1) Fees 0.00%                          
Other Expenses (as a percentage of Assets): [2] 0.02%                          
Expenses (as a percentage of Assets) 0.57%                          
Expense Example, with Redemption, 1 Year $ 58                          
Expense Example, with Redemption, 3 Years 183                          
Expense Example, with Redemption, 5 Years 318                          
Expense Example, with Redemption, 10 Years 714                          
Expense Example, No Redemption, 1 Year 58                          
Expense Example, No Redemption, 3 Years 183                          
Expense Example, No Redemption, 5 Years 318                          
Expense Example, No Redemption, 10 Years $ 714                          
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio                            
Prospectus Line Items                            
Risk/Return [Heading] Fund Summary Fund /Class: Energy Portfolio /Fidelity Advisor® Energy Fund A, M, C, I, Z                            
Objective [Heading] Investment Objective                          
Objective, Primary [Text Block] Energy Portfolio seeks capital appreciation.                          
Expense Heading [Optional Text] 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 19 of the prospectus and in the sales charge waiver appendix to the prospectus.                          
Shareholder Fees Caption [Optional Text] Shareholder fees                          
Operating Expenses Caption [Optional 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 15 % of the average value of its portfolio.                          
Portfolio Turnover, Rate 15.00%                          
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 19 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 at least 80% of assets in securities of companies principally engaged in the energy field, including the conventional areas of oil, gas, electricity, and coal, and newer sources of energy such as nuclear, geothermal, oil shale, and solar power. These companies may include, for example, integrated oil companies; drilling contractors and rig owners; drilling rig and equipment manufacturers and providers of supplies and services to companies engaged in oil and gas drilling; companies engaged in the exploration, production, refining, marketing, storage, or transportation of oil, gas, and/or refined products; and companies involved in the production and mining of coal, related products, and other consumable fuels. For purposes of the fund's policy to normally invest at least 80% of its assets in securities of companies principally engaged in the business activity or activities identified for the fund, Fidelity may consider a company to be principally engaged in the designated business activity or activities based on: (i) the level of a company's assets, income, sales, or profits that are committed to, derived from, or related to the designated business activity or activities, or (ii) whether a third party has given the company an industry or sector classification consistent with the designated business activity or activities. Whether a company is principally engaged in the designated business activity or activities can be determined under any of these factors. Effective December 11, 2025, 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.   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.                          
Strategy Portfolio Concentration [Text] Normally investing at least 80% of assets in securities of companies principally engaged in the energy field, including the conventional areas of oil, gas, electricity, and coal, and newer sources of energy such as nuclear, geothermal, oil shale, and solar power.                          
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 Energy Portfolio, 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 Energy Portfolio, 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 Energy Portfolio, 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                          
Bar Chart, Returns for Class Not Offered in Prospectus [Text] * The returns shown above are for Energy Portfolio, a class of shares of the fund that is not offered through this prospectus. Class A, Class M, Class C, Class I, and Class Z would have substantially similar annual returns to Energy Portfolio because the classes are invested in the same portfolio of securities. Class A's, Class M's, Class C's, Class I's, and Class Z's returns would differ from Energy Portfolio's returns only to the extent that the classes do not have the same expenses.                          
Year to Date Return, Label [Optional Text]    Year-to-Date Return                          
Bar Chart, Year to Date Return, Date Sep. 30, 2025                          
Bar Chart, Year to Date Return 9.08%                          
Highest Quarterly Return, Label [Optional Text]    Highest Quarter Return                          
Highest Quarterly Return, Date Mar. 31, 2022                          
Highest Quarterly Return 40.23%                          
Lowest Quarterly Return, Label [Optional Text]    Lowest Quarter Return                          
Lowest Quarterly Return, Date Mar. 31, 2020                          
Lowest Quarterly Return (52.25%)                          
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.                          
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | After Taxes on Distributions | Fidelity Advisor Energy Fund - Class A                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   Return After Taxes on Distributions                        
Average Annual Return, Percent   3.79%                     11.81% 3.92%
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | After Taxes on Distributions and Sales | Fidelity Advisor Energy Fund - Class A                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   Return After Taxes on Distributions and Sale of Fund Shares                        
Average Annual Return, Percent   2.86%                     9.81% 3.36%
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | F1509                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   MSCI U.S. IMI Energy 25-50 Index                        
Average Annual Return, Percent   6.67%                     12.76% 4.51%
SelectEnergyPortfolio-AMCIZPro | Select Energy Portfolio | SP001                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   S&P 500® Index                        
Average Annual Return, Percent   25.02%                     14.53% 13.10%
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | Fidelity Advisor Consumer Discretionary Fund - Class A                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 5.75%                          
Maximum Deferred Sales Charge (as a percentage) [4] 0.00%                          
Management Fees (as a percentage of Assets) [5] 0.70%                          
Distribution and Service (12b-1) Fees 0.25%                          
Other Expenses (as a percentage of Assets): [5] 0.03%                          
Expenses (as a percentage of Assets) 0.98%                          
Expense Example, with Redemption, 1 Year $ 669                          
Expense Example, with Redemption, 3 Years 869                          
Expense Example, with Redemption, 5 Years 1,086                          
Expense Example, with Redemption, 10 Years 1,707                          
Expense Example, No Redemption, 1 Year 669                          
Expense Example, No Redemption, 3 Years 869                          
Expense Example, No Redemption, 5 Years 1,086                          
Expense Example, No Redemption, 10 Years $ 1,707                          
Average Annual Return, Label [Optional Text]   Return Before Taxes                        
Average Annual Return, Percent   24.61%                     13.23% 12.15%
Annual Return [Percent]     24.61% 41.78% (34.83%) 19.15% 35.69% 27.04% (0.94%) 22.08% 4.35% 5.43%    
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | Fidelity Advisor Consumer Discretionary Fund - Class M                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 3.50%                          
Maximum Deferred Sales Charge (as a percentage) [4] 0.00%                          
Management Fees (as a percentage of Assets) [5] 0.72%                          
Distribution and Service (12b-1) Fees 0.50%                          
Other Expenses (as a percentage of Assets): [5] 0.03%                          
Expenses (as a percentage of Assets) 1.25%                          
Expense Example, with Redemption, 1 Year $ 473                          
Expense Example, with Redemption, 3 Years 733                          
Expense Example, with Redemption, 5 Years 1,012                          
Expense Example, with Redemption, 10 Years 1,808                          
Expense Example, No Redemption, 1 Year 473                          
Expense Example, No Redemption, 3 Years 733                          
Expense Example, No Redemption, 5 Years 1,012                          
Expense Example, No Redemption, 10 Years $ 1,808                          
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | Fidelity Advisor Consumer Discretionary Fund - Class C                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) [6] 1.00%                          
Management Fees (as a percentage of Assets) [5] 0.71%                          
Distribution and Service (12b-1) Fees 1.00%                          
Other Expenses (as a percentage of Assets): [5] 0.03%                          
Expenses (as a percentage of Assets) 1.74%                          
Expenses Deferred Charges [Text Block] On Class C shares redeemed less than one year after purchase.                          
Expense Example, with Redemption, 1 Year $ 277                          
Expense Example, with Redemption, 3 Years 548                          
Expense Example, with Redemption, 5 Years 944                          
Expense Example, with Redemption, 10 Years 1,851                          
Expense Example, No Redemption, 1 Year 177                          
Expense Example, No Redemption, 3 Years 548                          
Expense Example, No Redemption, 5 Years 944                          
Expense Example, No Redemption, 10 Years $ 1,851                          
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | Fidelity Advisor Consumer Discretionary Fund - Class I                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) 0.00%                          
Management Fees (as a percentage of Assets) [5] 0.69%                          
Distribution and Service (12b-1) Fees 0.00%                          
Other Expenses (as a percentage of Assets): [5] 0.03%                          
Expenses (as a percentage of Assets) 0.72%                          
Expense Example, with Redemption, 1 Year $ 74                          
Expense Example, with Redemption, 3 Years 230                          
Expense Example, with Redemption, 5 Years 401                          
Expense Example, with Redemption, 10 Years 894                          
Expense Example, No Redemption, 1 Year 74                          
Expense Example, No Redemption, 3 Years 230                          
Expense Example, No Redemption, 5 Years 401                          
Expense Example, No Redemption, 10 Years $ 894                          
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | Fidelity Advisor Consumer Discretionary Fund - Class Z                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) 0.00%                          
Management Fees (as a percentage of Assets) [5] 0.56%                          
Distribution and Service (12b-1) Fees 0.00%                          
Other Expenses (as a percentage of Assets): [5] 0.03%                          
Expenses (as a percentage of Assets) 0.59%                          
Expense Example, with Redemption, 1 Year $ 60                          
Expense Example, with Redemption, 3 Years 189                          
Expense Example, with Redemption, 5 Years 329                          
Expense Example, with Redemption, 10 Years 738                          
Expense Example, No Redemption, 1 Year 60                          
Expense Example, No Redemption, 3 Years 189                          
Expense Example, No Redemption, 5 Years 329                          
Expense Example, No Redemption, 10 Years $ 738                          
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio                            
Prospectus Line Items                            
Risk/Return [Heading] Fund Summary Fund /Class: Consumer Discretionary Portfolio /Fidelity Advisor® Consumer Discretionary Fund A, M, C, I, Z                            
Objective [Heading] Investment Objective                          
Objective, Primary [Text Block] Consumer Discretionary Portfolio seeks capital appreciation.                          
Expense Heading [Optional Text] 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 19 of the prospectus and in the sales charge waiver appendix to the prospectus.                          
Shareholder Fees Caption [Optional Text] Shareholder fees                          
Operating Expenses Caption [Optional 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 30 % of the average value of its portfolio.                          
Portfolio Turnover, Rate 30.00%                          
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 19 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 at least 80% of assets in securities of companies principally engaged in the manufacture and distribution of consumer discretionary products and services. These companies may include, for example, on-line retailers; department stores and specialty retailers including apparel, electronics, automotive, and home furnishing stores; manufacturers of auto parts and accessories, tire and rubber, autos, motorcycles, and scooters; manufacturers of consumer electronic products, including TVs and home audio equipment; manufacturers of household appliances and home furnishings; residential construction companies; manufacturers of leisure products; manufacturers of apparel, accessories, footwear, textiles, and luxury goods; gaming facility, hotel, cruise and travel agency owners and operators; restaurants and caterers; and companies providing educational, home security, legal, and personal services. For purposes of the fund's policy to normally invest at least 80% of its assets in securities of companies principally engaged in the business activity or activities identified for the fund, Fidelity may consider a company to be principally engaged in the designated business activity or activities based on: (i) the level of a company's assets, income, sales, or profits that are committed to, derived from, or related to the designated business activity or activities, or (ii) whether a third party has given the company an industry or sector classification consistent with the designated business activity or activities. Whether a company is principally engaged in the designated business activity or activities can be determined under any of these factors. Effective December 11, 2025, 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.   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.                          
Strategy Portfolio Concentration [Text] Normally investing at least 80% of assets in securities of companies principally engaged in the manufacture and distribution of consumer discretionary products and services.                          
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 Consumer Discretionary Portfolio, 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 Consumer Discretionary Portfolio, 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 Consumer Discretionary Portfolio, 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                          
Bar Chart, Returns for Class Not Offered in Prospectus [Text] * The returns shown above are for Consumer Discretionary Portfolio, a class of shares of the fund that is not offered through this prospectus. Class A, Class M, Class C, Class I, and Class Z would have substantially similar annual returns to Consumer Discretionary Portfolio because the classes are invested in the same portfolio of securities. Class A's, Class M's, Class C's, Class I's, and Class Z's returns would differ from Consumer Discretionary Portfolio's returns only to the extent that the classes do not have the same expenses.                          
Year to Date Return, Label [Optional Text]    Year-to-Date Return                          
Bar Chart, Year to Date Return, Date Sep. 30, 2025                          
Bar Chart, Year to Date Return 5.16%                          
Highest Quarterly Return, Label [Optional Text]    Highest Quarter Return                          
Highest Quarterly Return, Date Jun. 30, 2020                          
Highest Quarterly Return 31.89%                          
Lowest Quarterly Return, Label [Optional Text]    Lowest Quarter Return                          
Lowest Quarterly Return, Date Jun. 30, 2022                          
Lowest Quarterly Return (26.29%)                          
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.                          
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | After Taxes on Distributions | Fidelity Advisor Consumer Discretionary Fund - Class A                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   Return After Taxes on Distributions                        
Average Annual Return, Percent   22.54%                     11.67% 11.00%
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | After Taxes on Distributions and Sales | Fidelity Advisor Consumer Discretionary Fund - Class A                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   Return After Taxes on Distributions and Sale of Fund Shares                        
Average Annual Return, Percent   16.04%                     10.40% 9.86%
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | SP001                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   S&P 500® Index                        
Average Annual Return, Percent   25.02%                     14.53% 13.10%
SelectConsumerDiscretionaryPortfolio-AMCIZPro | Select Consumer Discretionary Portfolio | F1505                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   MSCI U.S. IMI Consumer Discretionary 25-50 Index                        
Average Annual Return, Percent   24.48%                     16.03% 14.04%
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | Fidelity Advisor Technology Fund - Class A                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 5.75%                          
Maximum Deferred Sales Charge (as a percentage) [7] 0.00%                          
Management Fees (as a percentage of Assets) [8] 0.65%                          
Distribution and Service (12b-1) Fees 0.25%                          
Other Expenses (as a percentage of Assets): [8] 0.01%                          
Expenses (as a percentage of Assets) 0.91%                          
Expense Example, with Redemption, 1 Year $ 663                          
Expense Example, with Redemption, 3 Years 848                          
Expense Example, with Redemption, 5 Years 1,050                          
Expense Example, with Redemption, 10 Years 1,630                          
Expense Example, No Redemption, 1 Year 663                          
Expense Example, No Redemption, 3 Years 848                          
Expense Example, No Redemption, 5 Years 1,050                          
Expense Example, No Redemption, 10 Years $ 1,630                          
Average Annual Return, Label [Optional Text]   Return Before Taxes                        
Average Annual Return, Percent   35.28%                     22.20% 21.07%
Annual Return [Percent]     35.28% 59.83% (36.87%) 21.97% 63.71% 51.07% (8.79%) 49.86% 11.94% 7.40%    
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | Fidelity Advisor Technology Fund - Class M                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 3.50%                          
Maximum Deferred Sales Charge (as a percentage) [7] 0.00%                          
Management Fees (as a percentage of Assets) [8] 0.65%                          
Distribution and Service (12b-1) Fees 0.50%                          
Other Expenses (as a percentage of Assets): [8] 0.01%                          
Expenses (as a percentage of Assets) 1.16%                          
Expense Example, with Redemption, 1 Year $ 464                          
Expense Example, with Redemption, 3 Years 706                          
Expense Example, with Redemption, 5 Years 966                          
Expense Example, with Redemption, 10 Years 1,710                          
Expense Example, No Redemption, 1 Year 464                          
Expense Example, No Redemption, 3 Years 706                          
Expense Example, No Redemption, 5 Years 966                          
Expense Example, No Redemption, 10 Years $ 1,710                          
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | Fidelity Advisor Technology Fund - Class C                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) [9] 1.00%                          
Management Fees (as a percentage of Assets) [8] 0.65%                          
Distribution and Service (12b-1) Fees 1.00%                          
Other Expenses (as a percentage of Assets): [8] 0.01%                          
Expenses (as a percentage of Assets) 1.66%                          
Expenses Deferred Charges [Text Block] On Class C shares redeemed less than one year after purchase.                          
Expense Example, with Redemption, 1 Year $ 269                          
Expense Example, with Redemption, 3 Years 523                          
Expense Example, with Redemption, 5 Years 902                          
Expense Example, with Redemption, 10 Years 1,766                          
Expense Example, No Redemption, 1 Year 169                          
Expense Example, No Redemption, 3 Years 523                          
Expense Example, No Redemption, 5 Years 902                          
Expense Example, No Redemption, 10 Years $ 1,766                          
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | Fidelity Advisor Technology Fund - Class I                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) 0.00%                          
Management Fees (as a percentage of Assets) [8] 0.66%                          
Distribution and Service (12b-1) Fees 0.00%                          
Other Expenses (as a percentage of Assets): [8] 0.00%                          
Expenses (as a percentage of Assets) 0.66%                          
Expense Example, with Redemption, 1 Year $ 67                          
Expense Example, with Redemption, 3 Years 211                          
Expense Example, with Redemption, 5 Years 368                          
Expense Example, with Redemption, 10 Years 822                          
Expense Example, No Redemption, 1 Year 67                          
Expense Example, No Redemption, 3 Years 211                          
Expense Example, No Redemption, 5 Years 368                          
Expense Example, No Redemption, 10 Years $ 822                          
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | Fidelity Advisor Technology Fund - Class Z                            
Prospectus Line Items                            
Maximum Cumulative Sales Charge (as a percentage of Offering Price) 0.00%                          
Maximum Deferred Sales Charge (as a percentage) 0.00%                          
Management Fees (as a percentage of Assets) [8] 0.54%                          
Distribution and Service (12b-1) Fees 0.00%                          
Other Expenses (as a percentage of Assets): [8] 0.01%                          
Expenses (as a percentage of Assets) 0.55%                          
Expense Example, with Redemption, 1 Year $ 56                          
Expense Example, with Redemption, 3 Years 176                          
Expense Example, with Redemption, 5 Years 307                          
Expense Example, with Redemption, 10 Years 689                          
Expense Example, No Redemption, 1 Year 56                          
Expense Example, No Redemption, 3 Years 176                          
Expense Example, No Redemption, 5 Years 307                          
Expense Example, No Redemption, 10 Years $ 689                          
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio                            
Prospectus Line Items                            
Risk/Return [Heading] Fund Summary Fund /Class: Technology Portfolio /Fidelity Advisor® Technology Fund A, M, C, I, Z                            
Objective [Heading] Investment Objective                          
Objective, Primary [Text Block] Technology Portfolio seeks capital appreciation.                          
Expense Heading [Optional Text] 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 19 of the prospectus and in the sales charge waiver appendix to the prospectus.                          
Shareholder Fees Caption [Optional Text] Shareholder fees                          
Operating Expenses Caption [Optional 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 44 % of the average value of its portfolio.                          
Portfolio Turnover, Rate 44.00%                          
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 19 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 at least 80% of assets in securities of companies principally engaged in offering, using, or developing products, processes, or services that will provide or will benefit significantly from technological advances and improvements. These companies may include, for example, manufacturers of communications equipment, products, and services, personal computers and other computer hardware components and peripherals; providers of information technology and systems integration services; companies developing and producing database management, home entertainment, educational, specialty, enterprise, and business software; manufacturers of electronic equipment, instruments or components, including copiers and faxes; semiconductor and related equipment manufacturers; and other information technology companies. For purposes of the fund's policy to normally invest at least 80% of its assets in securities of companies principally engaged in the business activity or activities identified for the fund, Fidelity may consider a company to be principally engaged in the designated business activity or activities based on: (i) the level of a company's assets, income, sales, or profits that are committed to, derived from, or related to the designated business activity or activities, or (ii) whether a third party has given the company an industry or sector classification consistent with the designated business activity or activities. Whether a company is principally engaged in the designated business activity or activities can be determined under any of these factors. Effective December 11, 2025, 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.   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.                          
Strategy Portfolio Concentration [Text] Normally investing at least 80% of assets in securities of companies principally engaged in offering, using, or developing products, processes, or services that will provide or will benefit significantly from technological advances and improvements.                          
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 Technology Portfolio, 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 Technology Portfolio, 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 Technology Portfolio, 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                          
Bar Chart, Returns for Class Not Offered in Prospectus [Text] * The returns shown above are for Technology Portfolio, a class of shares of the fund that is not offered through this prospectus. Class A, Class M, Class C, Class I, and Class Z would have substantially similar annual returns to Technology Portfolio because the classes are invested in the same portfolio of securities. Class A's, Class M's, Class C's, Class I's, and Class Z's returns would differ from Technology Portfolio's returns only to the extent that the classes do not have the same expenses.                          
Year to Date Return, Label [Optional Text]    Year-to-Date Return                          
Bar Chart, Year to Date Return, Date Sep. 30, 2025                          
Bar Chart, Year to Date Return 21.27%                          
Highest Quarterly Return, Label [Optional Text]    Highest Quarter Return                          
Highest Quarterly Return, Date Jun. 30, 2020                          
Highest Quarterly Return 36.41%                          
Lowest Quarterly Return, Label [Optional Text]    Lowest Quarter Return                          
Lowest Quarterly Return, Date Jun. 30, 2022                          
Lowest Quarterly Return (25.71%)                          
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.                          
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | After Taxes on Distributions | Fidelity Advisor Technology Fund - Class A                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   Return After Taxes on Distributions                        
Average Annual Return, Percent   33.71%                     19.69% 18.66%
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | After Taxes on Distributions and Sales | Fidelity Advisor Technology Fund - Class A                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   Return After Taxes on Distributions and Sale of Fund Shares                        
Average Annual Return, Percent   21.78%                     17.25% 16.96%
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | SP001                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   S&P 500® Index                        
Average Annual Return, Percent   25.02%                     14.53% 13.10%
SelectTechnologyPortfolio-AMCIZPro | Select Technology Portfolio | F1525                            
Prospectus Line Items                            
Average Annual Return, Label [Optional Text]   MSCI U.S. IMI Information Technology 25-50 Index                        
Average Annual Return, Percent   29.38%                     21.55% 20.54%
Document Type 485BPOS                          
Registrant Name Fidelity Select Portfolios                          
[1]
A 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.
[2]
A Based on estimated amounts for the current fiscal year.
[3]
B On Class C shares redeemed less than one year after purchase.
[4]
A 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.
[5]
A Based on estimated amounts for the current fiscal year.
[6]
B On Class C shares redeemed less than one year after purchase.
[7]
A 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.
[8]
A Based on estimated amounts for the current fiscal year.
[9]
B On Class C shares redeemed less than one year after purchase.