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iShares Short Maturity Municipal Bond Active ETF  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading iSHARES® SHORT MATURITY MUNICIPAL BOND ACTIVE ETF Ticker: MEARStock Exchange: Cboe BZX
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The iShares Short Maturity Municipal Bond Active ETF (the “Fund”) seeks to maximize tax-free current income.
Expense [Heading] rr_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
The following table describes the fees and expenses that you will incur if you buy, hold and sell shares of the Fund. The investment advisory agreement between iShares U.S. ETF Trust (the “Trust”) and BlackRock Fund Advisors (“BFA”) (the “Investment Advisory Agreement”) provides that BFA will pay all operating expenses of the Fund, except: (i) the management fees, (ii) interest expenses, (iii) taxes, (iv) expenses incurred with respect to the acquisition and disposition of portfolio securities and the execution of portfolio transactions, including brokerage commissions, (v) distribution fees or expenses, and (vi) litigation expenses and extraordinary expenses.
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments)1
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover.
Portfolio Turnover [Text Block] rr_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 91% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 91.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example.
Expense Example Narrative [Text Block] rr_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 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. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its net assets in municipal securities such that the interest on each bond is exempt from U.S. federal income taxes and the federal alternative minimum tax (“AMT”). Under normal circumstances, the Fund primarily invests in U.S. dollar-denominated, investment-grade short-term fixed- and floating-rate municipal securities with remaining maturities of five years or less, such as municipal bonds, municipal notes and variable rate demand obligations, as well as money market instruments and registered investment companies. Investment-grade securities are rated BBB- or higher by S&P Global Ratings and/or Fitch Ratings, Inc. (“Fitch”), or Baa3 or higher by Moody’s Investors Service, Inc. (“Moody's”), or, if unrated, determined by the Fund's management team to be of equivalent quality. Municipal bonds include debt obligations issued by or on behalf of a governmental entity or other qualifying issuer that pay interest that is, in the opinion of bond counsel to the issuer at the time of issuance, generally excludable from gross income for U.S. federal income tax purposes. The Fund may invest up to 20% of its net assets in municipal securities that pay interest that is subject to the federal AMT. Issuers may be states, territories and possessions of the U.S., including the District of Columbia, and their political subdivisions, agencies and instrumentalities. BFA or its affiliates may advise the money market funds and investment companies in which the Fund may invest.
Under normal circumstances, the effective duration of the Fund’s portfolio is expected to be 1.5 years or less, as calculated by the Fund’s management team. Effective duration is a measure of the Fund’s price sensitivity to changes in yields or interest rates; however, investors should be aware that effective duration is not an exact measurement and may not reliably predict a particular security’s price sensitivity to changes in yield or interest rates.
Under normal circumstances, the Fund will also seek to maintain a weighted average maturity that is less than three years. Weighted average maturity is a U.S. dollar-weighted average of the remaining term to maturity of the underlying securities in the Fund’s portfolio. The calculation of the Fund's weighted average maturity is based on the constituent securities' final maturity date or, for amortizing securities such as asset-backed and mortgage-backed securities, their weighted average life (i.e., the average length of time that each dollar of unpaid principal on the security remains outstanding).
The Fund is an actively managed exchange-traded fund (“ETF”) that does not seek to replicate the performance of a specified index. The Fund may have a higher degree of portfolio turnover than funds that seek to replicate the performance of an index.
The Fund is not a money market fund and does not seek to maintain a stable net asset value of $1.00 per share. Please see the Fund’s Statement of Additional Information (“SAI”) for further information.
Risk [Heading] rr_RiskHeading Summary of Principal Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance Information
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The performance information below illustrates how the Fund’s performance has varied over different periods and provides some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table compares the Fund’s performance to that of an appropriate broad-based securities market index and an additional index that Fund management believes more closely reflects the investment strategy of the Fund. Fund returns assume the reinvestment of any dividends and distributions. The Fund’s returns reflect the impact of any agreements to waive or reimburse expenses, which would reduce performance if not in effect. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information, including the Fund’s current NAV, may be obtained by visiting www.iShares.com or by calling 1-800-iShares (1-800-474-2737) (toll free).
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below illustrates how the Fund’s performance has varied over different periods and provides some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-iShares (1-800-474-2737) (toll free)
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.iShares.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year-by-Year Returns 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Return (%)
Period Ended
During the periods shown in the chart:
Best Quarter
1.60%
December 31, 2023
Worst Quarter
-0.67%
March 31, 2022
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (for the periods ended December 31, 2024) 
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns in the table above are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state or local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown are not relevant to tax-exempt investors or investors who hold shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher Fund returns after taxes on distributions and sales of Fund shares are calculated assuming that an investor has sufficient capital gains of the same character from other investments to offset any capital losses from the sales of Fund shares. As a result, Fund returns after taxes on distributions and sales of Fund shares may exceed Fund returns before taxes and/or returns after taxes on distributions.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
After-tax returns in the table above are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown are not relevant to tax-exempt investors or investors who hold shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”). Fund returns after taxes on distributions and sales of Fund shares are calculated assuming that an investor has sufficient capital gains of the same character from other investments to offset any capital losses from the sales of Fund shares. As a result, Fund returns after taxes on distributions and sales of Fund shares may exceed Fund returns before taxes and/or returns after taxes on distributions.
iShares Short Maturity Municipal Bond Active ETF | Risk Lose Money [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_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.
iShares Short Maturity Municipal Bond Active ETF | Municipal Securities Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Municipal Securities Risk. Municipal securities can be significantly affected by political or economic changes, including changes made in the law after issuance of the securities, as well as uncertainties in the municipal market related to taxation, legislative changes or the rights of municipal security holders, including in connection with an issuer insolvency. Municipal securities backed by current or anticipated revenues from a specific project or specific assets can be negatively affected by the inability to collect revenues from such projects or assets. Certain municipal securities are issued by entities with limited taxing authority such as school districts, or are dependent on revenue from a particular sector or industry, such as the utilities sector, infrastructure sector, or transportation industry.
iShares Short Maturity Municipal Bond Active ETF | Credit Risks [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Credit Risk. Debt issuers and other counterparties may be unable or unwilling to make timely interest and/or principal payments when due or otherwise honor their obligations. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also adversely affect the value of the Fund’s investment in that issuer. The degree of credit risk depends on an issuer's or counterparty's financial condition and on the terms of an obligation.
iShares Short Maturity Municipal Bond Active ETF | Interest Rate Risks [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Interest Rate Risk. Interest rate risk refers to the risk of fluctuations in the value of a fixed-income security due to changes in the general level of interest rates. Interest rate changes can be sudden and unpredictable and are influenced by a number of factors, including government policy, monetary policy, inflation expectations, perceptions of risk, and supply and demand for fixed-income securities. An increase in interest rates generally will cause the value of fixed-income securities to decline. Securities with longer maturities generally are more sensitive to interest rate changes and subject to greater fluctuations in value. Changes in interest rates may have unpredictable effects on fixed-income markets and result in heightened volatility and lower liquidity for certain instruments, which may adversely affect a Fund’s performance. During periods of very low or negative interest rates, a Fund may be unable to maintain positive returns or pay dividends to shareholders.
iShares Short Maturity Municipal Bond Active ETF | Risk of Investing in the US [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Risk of Investing in the U.S. Investing in U.S. issuers subjects the Fund to legal, regulatory, political, currency, security, and economic risks that are specific to the U.S. Certain changes in the U.S., such as a weakening of the U.S. economy or a decline in its financial markets, may have an adverse effect on U.S. issuers.
iShares Short Maturity Municipal Bond Active ETF | Market Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Market Risk. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. Local, regional or global events such as war, acts of terrorism, pandemics or other public health issues, recessions, the prospect or occurrence of a sovereign default or other financial crisis, or other events could have a significant impact on the Fund and its investments and could result in increased premiums or discounts to the Fund’s NAV.
iShares Short Maturity Municipal Bond Active ETF | Management Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Management Risk. The Fund is subject to management risk, which is the risk that the investment process, techniques, models and/or risk analyses applied by BFA will not produce the desired results. The securities or other assets selected by BFA may result in returns that are inconsistent with the Fund’s investment objective, and the Fund may underperform the market or any relevant benchmark. In addition, legislative, regulatory, or tax developments may affect the investment techniques available to BFA in connection with managing the Fund and may adversely affect the ability of the Fund to achieve its investment objective.
iShares Short Maturity Municipal Bond Active ETF | Asset Class Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Asset Class Risk. The securities and other assets in the Fund’s portfolio may underperform in comparison to financial markets generally, a particular financial market, an index, or other asset classes.
iShares Short Maturity Municipal Bond Active ETF | Authorized Participant Concentration Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Authorized Participant Concentration Risk.  An “Authorized Participant” is a member or participant of a clearing agency registered with the SEC, which has a written agreement with the Fund or one of its service providers that allows the Authorized Participant to place orders for the purchase and redemption of creation units (“Creation Units”). Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund. There are a limited number of institutions that may act as Authorized Participants for the Fund, including on an agency basis on behalf of other market participants. No Authorized Participant is obligated to engage in creation or redemption transactions. To the extent that Authorized Participants exit the business or do not place creation or redemption orders for the Fund and no other Authorized Participant places orders, Fund shares are more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting.
iShares Short Maturity Municipal Bond Active ETF | Call Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Call Risk. During periods of falling interest rates, an issuer of a callable bond held by the Fund may “call” or repay the security before its stated maturity, and the Fund may have to reinvest the proceeds in securities with lower yields, which would result in a decline in the Fund's income, or in securities with greater risks or with other less favorable features.
iShares Short Maturity Municipal Bond Active ETF | Cash Transactions Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Cash Transactions Risk. The Fund may effect part or all of its creations and redemptions for cash, rather than in-kind securities. As a result, the Fund may have to sell portfolio securities at inopportune times in order to obtain the cash needed to meet redemption orders. This may cause the Fund to sell a security and recognize a capital gain or loss that might not have been incurred if it had made a redemption in-kind. The use of cash creations and redemptions may also cause the Fund’s shares to trade in the market at wider bid-ask spreads or greater premiums or discounts to the Fund’s NAV.
iShares Short Maturity Municipal Bond Active ETF | Concentration Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Concentration Risk. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that
affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in the securities or other assets of one or more issuers, countries or other geographic units, markets, industries, project types, or asset classes.
iShares Short Maturity Municipal Bond Active ETF | Cybersecurity Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity Risk. Failures or breaches of the electronic systems of the Fund, its adviser, distributor, other service providers, counterparties, or issuers of assets in which the Fund invests may cause disruptions that negatively impact the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. The Fund cannot control the cybersecurity plans and systems of its service providers, counterparties, and other third parties whose activities affect the Fund. In addition, cyber incidents may adversely impact the issuers of securities in which the Fund invests, which may cause such investments to lose value.
iShares Short Maturity Municipal Bond Active ETF | Floating Rate Securities Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Floating Rate Securities Risk. Securities with floating or variable interest rates can be less sensitive to interest rate changes than securities with fixed interest rates, but may decline in value if their coupon rates do not reset as high, or as quickly, as comparable market interest rates, and generally carry lower yields than fixed securities of the same maturity. Although floating rate securities are less sensitive to interest rate risk than fixed-rate securities, they are subject to credit risk and default risk, which could impair their value.
iShares Short Maturity Municipal Bond Active ETF | Illiquid Investments Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Illiquid Investments Risk. An illiquid investment is any investment that the Fund reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without significantly changing the market value of the investment. To the extent the Fund holds illiquid investments, the illiquid investments may reduce its returns because the Fund may be unable to transact at advantageous times or prices. In addition, if the Fund is limited in its ability to sell illiquid investments during periods when shareholders are redeeming their shares, it will need to sell liquid securities to meet redemption requests and illiquid securities will become a larger portion of the Fund’s holdings. During periods of market volatility, liquidity in the market for Fund shares may be impacted by the liquidity in the market for the underlying securities or other assets held by the Fund, which could lead to Fund shares trading at a premium or discount to the Fund’s NAV.
iShares Short Maturity Municipal Bond Active ETF | Income Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Income Risk. The Fund’s income may decline when interest rates fall because the Fund may hold a significant portion of short duration securities and/or securities that have floating or variable interest rates. The Fund’s income may decline because the Fund invests in lower yielding bonds, and as the bonds in its portfolio mature, are near maturity or are called, the Fund needs to purchase additional bonds.
iShares Short Maturity Municipal Bond Active ETF | Issuer Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Issuer Risk. The performance of the Fund depends on the performance of individual securities or other assets to which the Fund has exposure. The value of securities or other assets may decline, or perform differently from the market as a whole, due to changes in the financial condition or credit rating of the issuer or counterparty.
iShares Short Maturity Municipal Bond Active ETF | Large Shareholder and Large Scale Redemption Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Large Shareholder and Large-Scale Redemption Risk. Certain shareholders of the Fund, including an Authorized Participant, a third-party investor, the Fund’s adviser, an affiliate of the Fund’s adviser, a market maker, or another entity, may from time to time own or manage a substantial amount of Fund shares, or may hold their investment in the Fund for a limited period of time. There can be no assurance that any large shareholder or large group of shareholders would not redeem their investment. Redemptions of a large number of Fund shares could require the Fund to dispose of assets to meet the redemption requests, which can accelerate the realization of taxable income and/or capital gains and cause the Fund to make taxable distributions to its shareholders earlier than the Fund otherwise would have. In addition, under certain circumstances, non-redeeming shareholders may be treated as receiving a disproportionately large taxable distribution during or with respect to such year. In some circumstances, the Fund may hold a relatively large proportion of its assets in cash in anticipation of large redemptions, diluting its investment returns. These large redemptions may also force the Fund to sell portfolio securities or other assets when it might not otherwise do so, which may negatively impact the Fund’s NAV, increase the Fund’s brokerage costs and/or have a material effect on the market price of Fund shares.
iShares Short Maturity Municipal Bond Active ETF | Market Trading Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares (including through a trading halt), losses from trading in secondary markets, periods of high volatility, and disruptions in the process of creating and redeeming Fund shares. Any of these factors, among others, may lead to the Fund’s shares trading in the secondary market at a premium or discount to NAV or to the intraday value of the Fund’s portfolio holdings. If you buy Fund shares at a time when the market price is at a premium to NAV or sell Fund shares at a time when the market price is at a discount to NAV, you may pay significantly more or receive significantly less than the underlying value of the Fund shares.
iShares Short Maturity Municipal Bond Active ETF | Not a Money Market Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Not a Money Market Fund. The Fund is not a money market fund and is not subject to the strict rules that govern the quality,
maturity, liquidity and other features of securities that money market funds may purchase. Under normal circumstances, the Fund’s investments may be more susceptible than a money market fund is to credit risk, interest rate risk, valuation risk and other risks relevant to the Fund’s investments. The Fund does not seek to maintain a stable net asset value of $1.00 per share.
iShares Short Maturity Municipal Bond Active ETF | Operational Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_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. The Fund and BFA seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address significant operational risks.
iShares Short Maturity Municipal Bond Active ETF | Tax Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Tax Risk. There is no guarantee that the Fund's income will be exempt from U.S. federal income taxes, the federal AMT or the federal Medicare contribution tax of 3.8% on “net investment income.”
iShares Short Maturity Municipal Bond Active ETF | Valuation Risk [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock
Valuation Risk. The price that the Fund could receive upon the sale (or other disposition) of a security or other asset may differ from the Fund’s valuation of the security or other asset, particularly for securities or other assets that trade in low volume or volatile markets or that are valued using a fair value methodology. In addition, the value of the securities or other assets in the Fund’s portfolio may change on days or during time periods when investors are not able to purchase or sell Fund shares. Authorized Participants that create or redeem Fund shares on days when the Fund is holding fair-valued securities or other assets may receive fewer or more shares, or lower or higher redemption proceeds, than they would have received had the securities or other assets not been fair valued or been valued using a different methodology. The ability to value investments may be impacted by technological issues or errors by pricing services or other third-party service providers.
iShares Short Maturity Municipal Bond Active ETF | iShares Short Maturity Municipal Bond Active ETF  
Risk/Return: rr_RiskReturnAbstract  
Management Fees rr_ManagementFeesOverAssets 0.25% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none [1]
Other Expenses rr_OtherExpensesOverAssets none [1],[2]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.25% [1]
1 Year rr_ExpenseExampleYear01 $ 26
3 Years rr_ExpenseExampleYear03 80
5 Years rr_ExpenseExampleYear05 141
10 Years rr_ExpenseExampleYear10 $ 318
2016 rr_AnnualReturn2016 0.59%
2017 rr_AnnualReturn2017 0.97%
2018 rr_AnnualReturn2018 1.58%
2019 rr_AnnualReturn2019 2.03%
2020 rr_AnnualReturn2020 1.11%
2021 rr_AnnualReturn2021 0.06%
2022 rr_AnnualReturn2022 0.15%
2023 rr_AnnualReturn2023 3.96%
2024 rr_AnnualReturn2024 3.36%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 1.60%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (0.67%)
One Year rr_AverageAnnualReturnYear01 3.36%
Five Years rr_AverageAnnualReturnYear05 1.71%
Since Fund Inception rr_AverageAnnualReturnSinceInception 1.43%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 03, 2015
iShares Short Maturity Municipal Bond Active ETF | Return After Taxes on Distributions | iShares Short Maturity Municipal Bond Active ETF  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 3.36%
Five Years rr_AverageAnnualReturnYear05 1.71%
Since Fund Inception rr_AverageAnnualReturnSinceInception 1.43%
iShares Short Maturity Municipal Bond Active ETF | Return After Taxes on Distributions and Sale of Fund Shares | iShares Short Maturity Municipal Bond Active ETF  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 3.41%
Five Years rr_AverageAnnualReturnYear05 1.73%
Since Fund Inception rr_AverageAnnualReturnSinceInception 1.44%
iShares Short Maturity Municipal Bond Active ETF | Bloomberg Municipal Bond Index (Returns do not reflect deductions for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 1.05% [3]
Five Years rr_AverageAnnualReturnYear05 0.99% [3]
Since Fund Inception rr_AverageAnnualReturnSinceInception 2.24% [3]
iShares Short Maturity Municipal Bond Active ETF | Bloomberg Municipal Bond: 1 Year (1-2) Index (Returns do not reflect deductions for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 2.71% [4]
Five Years rr_AverageAnnualReturnYear05 1.39% [4]
Since Fund Inception rr_AverageAnnualReturnSinceInception 1.30% [4]
[1] Operating expenses paid by BFA under the Investment Advisory Agreement exclude acquired fund fees and expenses, if any.
[2] The amount rounded to 0.00%.
[3] The Fund has added this broad-based index in response to new regulatory requirements.
[4] The Bloomberg Municipal Bond: 1 Year (1-2) Index is an unmanaged index comprised of national municipal bond issues having a maturity of at least one year and less than two years.