v3.26.1
Label Element Value
SEI Select Small Cap ETF | SEI Select Small Cap ETF  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk/Return [Heading] oef_RiskReturnHeading SEI Select Small Cap ETF
Objective [Heading] oef_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] oef_ObjectivePrimaryTextBlock

Capital appreciation.
Expense Heading [Optional Text] oef_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] oef_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that you will incur if 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 fee table or example below.
Operating Expenses Caption [Optional Text] oef_OperatingExpensesCaption Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments)
Expense Example [Heading] oef_ExpenseExampleHeading Example.
Expense Example Narrative [Text Block] oef_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of owning shares of the Fund with the cost of investing in other funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Expense Example by, Year, Caption [Text] oef_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Portfolio Turnover [Heading] oef_PortfolioTurnoverHeading Portfolio Turnover.
Portfolio Turnover [Text Block] oef_PortfolioTurnoverTextBlock

The Fund may pay 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 the Annual Fund Operating Expenses or in the Example, affect the Fund's performance.

During the most recent fiscal year, the Fund's portfolio turnover rate was 98% of the average value of its portfolio.
Portfolio Turnover, Rate oef_PortfolioTurnoverRate 98.00%
Strategy [Heading] oef_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] oef_StrategyNarrativeTextBlock

Under normal circumstances, the SEI Select Small Cap ETF (the Fund) will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in equity securities of small companies. For purposes of this Fund, a small company is a company with a market capitalization in the range of companies in the Russell 2000 Index (between $50.89 million and $13.80 billion as of June 30, 2026) (the Index), as determined at the time of purchase. The market capitalization range and the composition of the Index are subject to change, and the Fund is not limited to investing only in companies within the Index. The Fund may also invest in securities of mid capitalization companies, which will not be considered "small companies" to the extent they fall outside the market capitalization range of the Index for purposes of the Fund's 80% policy.

The Fund will utilize an integrated management approach where SEI Investments Management Corporation (SIMC or the Adviser) will combine its own proprietary quantitative-based, active stock portfolio, with model portfolios from one or more Sub-Advisers to construct the Fund's portfolio.

SIMC's quantitative model evaluates all of the securities in the investment universe of small capitalization issuers based on certain characteristics (Factors) that are determined by the Adviser, such as Value, Momentum, Quality and Low Volatility. Each of these factor families are described in further detail in the "More Information About the Funds — Factors" section. The Adviser uses its own judgment and model-based systems to assess which Factors to use and to determine what portion of the Fund's assets should be invested in each security identified. However, based on perceived market opportunities, the Adviser may reallocate the Fund's assets to tilt in favor of one or more Factors. The Adviser may add, remove or modify certain Factors in its model based on investment research or in response to changes in market conditions.

SIMC will select Sub-Advisers who on an ongoing basis provide a model portfolio composed of the Sub-Adviser's recommendations as to the securities to be purchased, sold or retained by the Fund (the Sub-Adviser's securities list). Taking into account the investment objective of the Fund, SIMC may incorporate the recommendations contained in the Sub-Adviser's securities list, in whole or in part, when it trades securities within the Fund in the aggregate. Securities recommended or suggested for purchase within the Sub-Adviser's securities list are assessed by SIMC and considered alongside securities identified by SIMC for purchase or sale in the Fund. SIMC will determine the constituents and weightings of securities held by the Fund and the securities held within the Fund may not have the same weightings of securities as those contained within the Sub-Adviser's securities list as SIMC may choose, whether substantially or entirely to disregard the Sub-Adviser's securities list when implementing trades in aggregate within the Fund. The Adviser may adjust the securities in the Fund to implement its forward-looking views regarding various portfolio characteristics, or for risk management purposes.
Summary of Definition of Rule 35d-1 Term in Fund Name [Text Block] fnd_NmRule35d1TermDfnSmryTextBlock For purposes of this Fund, a small company is a company with a market capitalization in the range of companies in the Russell 2000 Index (between $50.89 million and $13.80 billion as of June 30, 2026) (the Index), as determined at the time of purchase. The market capitalization range and the composition of the Index are subject to change, and the Fund is not limited to investing only in companies within the Index. The Fund may also invest in securities of mid capitalization companies, which will not be considered "small companies" to the extent they fall outside the market capitalization range of the Index for purposes of the Fund's 80% policy.
Summary of Selection Criteria for Rule 35d-1 Term in Fund Name [Text Block] fnd_NmRule35d1TermSlctnCritSmryTextBlock SIMC's quantitative model evaluates all of the securities in the investment universe of small capitalization issuers based on certain characteristics (Factors) that are determined by the Adviser, such as Value, Momentum, Quality and Low Volatility. Each of these factor families are described in further detail in the "More Information About the Funds — Factors" section. The Adviser uses its own judgment and model-based systems to assess which Factors to use and to determine what portion of the Fund's assets should be invested in each security identified. However, based on perceived market opportunities, the Adviser may reallocate the Fund's assets to tilt in favor of one or more Factors. The Adviser may add, remove or modify certain Factors in its model based on investment research or in response to changes in market conditions.
Rule 35d-1 Eighty Percent Investment Policy [Text Block] fnd_NmRule35d1EightyPctInvstmntPlcyTextBlock Under normal circumstances, the SEI Select Small Cap ETF (the Fund) will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in equity securities of small companies. For purposes of this Fund, a small company is a company with a market capitalization in the range of companies in the Russell 2000 Index (between $50.89 million and $13.80 billion as of June 30, 2026) (the Index), as determined at the time of purchase. The Fund may also invest in securities of mid capitalization companies, which will not be considered "small companies" to the extent they fall outside the market capitalization range of the Index for purposes of the Fund's 80% policy.
Bar Chart and Performance Table [Heading] oef_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] oef_PerformanceNarrativeTextBlock

The bar chart and the performance table below provide some indication of the risks of investing in the Fund by showing the Fund's performance for the past calendar year and by showing how the Fund's average annual returns for 1 year and since the Fund's inception compare with those of a broad measure of market performance. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. For current performance information, please call 1-800-DIAL-SEI.
Performance Information Illustrates Variability of Returns [Text] oef_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and the performance table below provide some indication of the risks of investing in the Fund by showing the Fund's performance for the past calendar year and by showing how the Fund's average annual returns for 1 year and since the Fund's inception compare with those of a broad measure of market performance.
Performance Availability Phone [Text] oef_PerformanceAvailabilityPhone 1-800-DIAL-SEI
Performance Past Does Not Indicate Future [Text] oef_PerformancePastDoesNotIndicateFuture The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart Closing [Text Block] oef_BarChartClosingTextBlock

Best Quarter: 9.20% (9/30/2025)
Worst Quarter: -7.23% (3/31/2025)
The Fund's total return (pre-tax) from January 1, 2026 to June 30, 2026 was 20.15%
Year to Date Return, Label [Optional Text] oef_YearToDateReturnLabel The Fund's total return (pre-tax)
Bar Chart, Year to Date Return, Date oef_BarChartYearToDateReturnDate Jun. 30, 2026
Bar Chart, Year to Date Return oef_BarChartYearToDateReturn 20.15%
Highest Quarterly Return, Label [Optional Text] oef_HighestQuarterlyReturnLabel Best Quarter:
Highest Quarterly Return, Date oef_BarChartHighestQuarterlyReturnDate Sep. 30, 2025
Highest Quarterly Return oef_BarChartHighestQuarterlyReturn 9.20%
Lowest Quarterly Return, Label [Optional Text] oef_LowestQuarterlyReturnLabel Worst Quarter:
Lowest Quarterly Return, Date oef_BarChartLowestQuarterlyReturnDate Mar. 31, 2025
Lowest Quarterly Return oef_BarChartLowestQuarterlyReturn (7.23%)
Performance Table Heading oef_PerformanceTableHeading Average Annual Total Returns (for the periods ended December 31, 2025)
Index No Deduction for Fees, Expenses, or Taxes [Text] oef_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Performance Table Uses Highest Federal Rate oef_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred oef_PerformanceTableNotRelevantToTaxDeferred After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table Narrative oef_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Risk Lose Money [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Risk Not Insured [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

An investment in the Fund is not a bank deposit and it is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency, SIMC or any of its affiliates.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Equity Securities Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Equity Securities Risk. Equity securities are subject to changes in value, and their values may be more volatile than those of other asset classes.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Small and Medium Capitalization Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Small and Medium Capitalization Risk. The risk that small and medium capitalization companies in which the Fund may invest may be more vulnerable to adverse business or economic events than larger, more established companies. In particular, small and medium capitalization companies may have limited product lines, markets and financial resources and may depend upon a relatively small management group. Therefore, small capitalization and medium capitalization stocks may be more volatile than those of larger companies. Small capitalization and medium capitalization stocks may be traded over-the-counter (OTC). OTC stocks may trade less frequently and in smaller volume than exchange listed stocks and may have more price volatility than that of exchange-listed stocks.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Momentum Securities Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Momentum Securities Risk. Stocks that previously exhibited high momentum characteristics may not experience positive momentum or may experience more volatility than the market as a whole.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Quality Securities Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Quality Securities Risk. There is no guarantee that the past performance of stocks that SIMC or a Sub-Adviser determines are quality will continue. Companies that issue these stocks may experience lower than expected returns or may experience negative growth, as well as increased leverage, resulting in lower than expected or negative returns to Fund shareholders. Many factors can affect a stock's quality and performance, and the impact of these factors on a stock or its price can be difficult to predict.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Value Securities Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Value Securities Risk. Securities issued by companies that may be perceived as undervalued may fail to appreciate for long periods of time and may never realize their full potential value. SIMC or a Sub-Adviser may be unsuccessful in identifying undervalued securities. Value securities have generally performed better than non-value securities during periods of economic recovery (although there is no assurance that they will continue to do so). Value securities may go in and out of favor over time.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Low Volatility Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Low Volatility Risk. Although subject to the risks of common stocks, low volatility stocks are seen as having a lower risk profile than the overall markets. However, a portfolio comprised of low volatility stocks may not produce investment exposure that has lower variability to changes in such stocks' price levels. Low volatility stocks are likely to underperform the broader market during periods of rapidly rising stock prices when market volatility is high. Low volatility stocks also may not protect against market declines.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Quantitative Investing Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Quantitative Investing Risk. Due to the significant role technology plays in quantitative strategies, they carry the risk of unintended or unrecognized issues or flaws in the design, coding, implementation or maintenance of the computer programs or technology used in the development and implementation of the quantitative strategy. Utility interruptions or other key systems outages also can impair the performance of quantitative investment strategies.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Market Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Market Risk. The market value of a security may move up and down, sometimes rapidly and unpredictably. Market risk may affect a single issuer, an industry, a sector or the equity or bond market as a whole. The Fund's market price may deviate from the value of the Fund's underlying portfolio holdings, particularly in times of market stress, with the result that investors may pay significantly more or receive significantly less than the underlying value of the Fund shares bought or sold. This can be reflected as a spread between the bid and ask prices for the Fund quoted during the day or a premium or discount in the closing price from the Fund's NAV.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Risk of Investing in the U.S. [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Risk of Investing in the U.S. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Issuer Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Issuer Risk. The performance of the Fund depends on the performance of individual securities to which the Fund has exposure. Changes in the financial condition or credit rating of an issuer of those securities may cause the value of the Fund to decline.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Market Trading Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, periods of high volatility and disruptions in the creation/redemption process. Active trading markets for the Fund's shares may not be developed or maintained by market makers or Authorized Participants (as defined below). Authorized Participants are not obligated to make a market in the Fund's shares or to submit purchase or redemption orders for Creation Units (as defined below). In times of market stress, market makers or Authorized Participants may step away from their respective roles, which could lead to variances between the market price of the Fund's shares and its underlying NAV. Trading in shares on an exchange may be halted in certain circumstances. If a trading halt occurs, a shareholder may temporarily be unable to purchase or sell shares of the Fund. Any of these factors could lead the Fund's shares to trade at a premium or discount to NAV. Thus, you may pay more (or less) than NAV when you buy shares of the Fund in the secondary market, and you may receive less (or more) than NAV when you sell those shares in the secondary market, particularly during times of market stress. SIMC or a Sub-Adviser cannot predict whether shares will trade above (premium), below (discount) or at NAV or whether the spread between bid and ask prices will widen. In addition, there can be no assurance that the requirements of the listing exchange necessary to maintain the listing of the Fund will continue to be met.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Liquidity Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Liquidity Risk. In stressed market conditions, the market for a Fund's shares may become less liquid in response to deteriorating liquidity in the markets for the Fund's underlying portfolio holdings. This adverse effect on liquidity for the Fund's shares in turn could lead to differences between the market price of the Fund's shares and its underlying NAV and/or widening the spread between bid and ask prices.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Management Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Management Risk. SIMC or a Sub-Adviser may not successfully implement the Fund's investment strategies and, as a result, the Fund may not meet its investment objective and/or underperform other investment vehicles with similar investment objectives and strategies. Errors or delays in coordinating creation and redemption basket processes among Sub-Advisers can also reduce the Fund's performance.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Operational Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund's service providers, counterparties or other third parties, failed or inadequate processes and technology or systems failures.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Authorized Participant Concentration Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Authorized Participant Concentration Risk. Only broker-dealers (referred to as Authorized Participants or APs) that have executed authorized participation agreements with respect to the Trust may engage in creation or redemption transactions directly with the Fund, and no AP is obligated to engage in creation and/or redemption transactions. To the extent that APs exit the business or are unable to proceed with orders, Fund shares may be more likely to trade at a premium or discount to NAV, have wider spreads between bid and ask prices, have wider spreads between bid and ask prices or face trading halts or delisting.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | Cybersecurity Risk [Member]  
Prospectus [Line Items] oef_ProspectusLineItems  
Risk [Text Block] oef_RiskTextBlock

Cybersecurity Risk. Failures or breaches of the electronic systems of the Fund, SIMC, a Sub-Adviser, the Fund's distributor, and other service providers, market makers, APs or the issuers of securities in which the

Fund invests have the ability to cause disruptions, negatively impact the Fund's business operations and/or potentially result in financial losses to the Fund and its shareholders.
SEI Select Small Cap ETF | SEI Select Small Cap ETF | SEI Select Small Cap ETF  
Prospectus [Line Items] oef_ProspectusLineItems  
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.55% [1]
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 0.00%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.00% [1],[2]
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 0.55%
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 56
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 176
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 307
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 689
Expense Example, No Redemption, 1 Year oef_ExpenseExampleNoRedemptionYear01 56
Expense Example, No Redemption, 3 Years oef_ExpenseExampleNoRedemptionYear03 176
Expense Example, No Redemption, 5 Years oef_ExpenseExampleNoRedemptionYear05 307
Expense Example, No Redemption, 10 Years oef_ExpenseExampleNoRedemptionYear10 $ 689
SEI Select Small Cap ETF | Russell 2000 Index Return (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] oef_ProspectusLineItems  
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Russell 2000 Index Return (reflects no deduction for fees, expenses or taxes)
Average Annual Return, Percent oef_AvgAnnlRtrPct 12.81%
Average Annual Return, Percent oef_AvgAnnlRtrPct 12.01%
SEI Select Small Cap ETF | SEI Select Small Cap ETF  
Prospectus [Line Items] oef_ProspectusLineItems  
Annual Return [Percent] oef_AnnlRtrPct 9.81%
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Return Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 9.81%
Average Annual Return, Percent oef_AvgAnnlRtrPct 9.11%
SEI Select Small Cap ETF | SEI Select Small Cap ETF | After Taxes on Distributions  
Prospectus [Line Items] oef_ProspectusLineItems  
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Return After Taxes on Distributions
Average Annual Return, Percent oef_AvgAnnlRtrPct 9.64%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.92%
SEI Select Small Cap ETF | SEI Select Small Cap ETF | After Taxes on Distributions and Sales  
Prospectus [Line Items] oef_ProspectusLineItems  
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
Average Annual Return, Percent oef_AvgAnnlRtrPct 5.91%
Average Annual Return, Percent oef_AvgAnnlRtrPct 6.94%
[1] The investment advisory agreement between SEI Exchange Traded Funds (the Trust) and SEI Investments Management Corporation (SIMC), the Fund's adviser (the Investment Advisory Agreement) provides that SIMC will pay all operating expenses of the Fund, except the management fees, interest expenses, dividend and other expenses on securities sold short, taxes, expenses incurred with respect to the acquisition and disposition of portfolio securities and the execution of portfolio transactions (including brokerage commissions), acquired fund fees and expenses, distribution fees or expenses paid by the Trust under any distribution plan adopted pursuant to Rule 12b-1 under the 1940 Act (if any), fees and expenses of the Board of Trustees, litigation expenses and any extraordinary expenses.
[2] The amount rounded to 0.00%.