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Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName iSHARES TRUST
Prospectus Date rr_ProspectusDate Jun. 12, 2014
iShares Core GNMA Bond ETF
 
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading iSHARES® CORE GNMA BOND ETF
Ticker: GNMA                                  Stock Exchange: NASDAQ
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The iShares Core GNMA Bond ETF (the “Fund”) seeks to track the investment results of an index composed of mortgage-backed pass-through securities guaranteed by the Government National Mortgage Association (“GNMA” or “Ginnie Mae”).
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 own shares of the Fund. The investment advisory agreement between iShares Trust (the “Trust”) and BlackRock Fund Advisors (“BFA”) (the “Investment Advisory Agreement”) provides that BFA will pay all operating expenses of the Fund, except interest expenses, taxes, brokerage expenses, future distribution fees or expenses, and extraordinary expenses. The Fund will also pay Acquired Fund Fees and Expenses. “Acquired Fund Fees and Expenses” reflects the Fund's pro rata share of the fees and expenses incurred by investing in other investment companies. The impact of Acquired Fund Fees and Expenses will be included in the total returns of the Fund. Acquired Fund Fees and Expenses are not used to calculate the Fund's net asset value per share (“NAV”) and are not included in the calculation of the ratio of expenses to average net assets shown in the Financial Highlights section of the Fund's prospectus (the “Prospectus”). BFA, the investment adviser to the Fund, has contractually agreed to waive its management fees in an amount equal to Acquired Fund Fees and Expenses attributable to the Fund's investment in other registered investment companies through December 31, 2015. The contractual waiver may be terminated prior to December 31, 2015 only upon written agreement of the Trust and BFA.

You may also incur usual and customary brokerage commissions when buying or selling shares of the Fund, which are not reflected in the Example that follows:
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)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination December 31, 2015
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 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 1,335% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 1335.00%
Expense Exchange Traded Fund Commissions [Text] rr_ExpenseExchangeTradedFundCommissions You may also incur usual and customary brokerage commissions when buying or selling shares of the Fund, which are not reflected in the Example that follows:
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The expense information in the table above has been restated, as of the Fund's most recent fiscal year end, to reflect current fees.
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees Acquired Fund Fees and Expenses are not used to calculate the Fund's net asset value per share (“NAV”) and are not included in the calculation of the ratio of expenses to average net assets shown in the Financial Highlights section of the Fund's prospectus (the “Prospectus”).
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 track the investment results of the Barclays U.S. GNMA Bond Index (the “Underlying Index”), which is a market capitalization-weighted index that measures the performance of mortgage-backed pass-through securities issued by GNMA.

The Underlying Index includes fixed-rate mortgage pass-through securities issued by GNMA that have 30- or 15-year maturities. All securities in the Underlying Index must have a weighted average maturity of at least one year and have $250 million or more of outstanding face value. The securities in the Underlying Index are updated on the last calendar day of each month.

BFA uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” the index it tracks and does not seek temporary defensive positions when markets decline or appear overvalued.

Indexing may eliminate the chance that the Fund will substantially outperform the Underlying Index but also may reduce some of the risks of active management, such as poor security selection. Indexing seeks to achieve lower costs and better after-tax performance by keeping portfolio turnover low in comparison to actively managed investment companies.

BFA uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. The securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability, duration, maturity or credit ratings and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities in the Underlying Index.

The Fund generally invests at least 90% of its assets in the securities of the Underlying Index and in investments that provide substantially similar exposure to the securities in the Underlying Index. However, the Fund may at times invest up to 20% of its assets in cash and cash equivalents, including money market funds advised by BFA or its affiliates, as well as in mortgage-backed pass-through securities issued by GNMA and treasury bonds not included in the Underlying Index, but which BFA believes will help the Fund track the Underlying Index.

Most transactions in mortgage-backed pass-through securities occur through standardized contracts for future delivery in which the exact mortgage pools to be delivered are not specified until a few days prior to settlement (“to-be-announced (TBA) transactions”). The Fund may enter into such contracts for fixed-rate pass-through securities on a regular basis. The Fund, pending settlement of such contracts, will invest the relevant assets in liquid, short-term instruments, including shares of money market funds advised by BFA or its affiliates. The Fund will assume its pro rata share of the fees and expenses of any money market fund that it may invest in, in addition to the Fund's own fees and expenses. The Fund may also acquire interests in mortgage pools through means other than such standardized contracts for future delivery. The Fund seeks to track the investment results of the Underlying Index before the fees and expenses of the Fund.

The Fund’s investments in mortgage-backed pass-through securities (including transactions occurring through TBAs) will be limited to GNMA issuances.

The Fund may lend securities representing up to one-third of the value of the Fund's total assets (including the value of the collateral received).

The Underlying Index is sponsored by an organization (the “Index Provider”) that is independent of the Fund and BFA. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index. The Fund’s Index Provider is Barclays Capital Inc. or its affiliates (“Barclays”).

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and instrumentalities), repurchase agreements collateralized by U.S. government securities, and securities of state or municipal governments and their political subdivisions are not considered to be issued by members of any industry.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and instrumentalities), repurchase agreements collateralized by U.S. government securities, and securities of state or municipal governments and their political subdivisions are not considered to be issued by members of any industry.
Risk [Heading] rr_RiskHeading Summary of Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock 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. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund's NAV, trading price, yield, total return and ability to meet its investment objective.

Asset Class Risk. Securities in the Underlying Index or in the Fund's portfolio may underperform in comparison to the general securities markets, a particular securities market, or other asset classes.

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 at lower interest rates, resulting in a decline in the Fund's income.

Concentration Risk. The Fund may be susceptible to an increased risk of loss due to adverse occurrences to the extent that the Fund's investments are concentrated in a particular issuer or issuers, country, group of countries, region, market, industry, group of industries, sector or asset class.

Extension Risk. During periods of rising interest rates, certain debt obligations will be paid off substantially more slowly than originally anticipated and the value of those securities may fall sharply, resulting in a decline in the Fund’s income and potentially in the value of the Fund’s investments.

GNMA Mortgage-Backed Securities Risk. Mortgage-backed securities (“MBS”) represent interests in “pools” of mortgages and are subject to credit, interest rate, prepayment and extension risk. MBS react differently to changes in interest rates than other bonds and the prices of MBS may reflect adverse economic and market conditions. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain MBS. Default or bankruptcy of a counterparty to a TBA transaction would expose the Fund to possible loss.

High Portfolio Turnover Risk. The Fund may engage in active and frequent trading of its portfolio securities. High portfolio turnover (higher than 100%) may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs on the sale of the securities and on reinvestment in other securities.

Income Risk. The Fund's income may decline when interest rates fall. This decline can occur because the Fund must invest in lower-yielding bonds as bonds in its portfolio mature, bonds in the Underlying Index are substituted or the Fund otherwise needs to purchase additional bonds.

Index-Related Risk. There is no guarantee that the Fund will achieve a high degree of correlation to the Underlying Index and therefore achieve its investment objective. Market disruptions and regulatory restrictions could have an adverse effect on the Fund’s ability to adjust its exposure to the required levels in order to track the Underlying Index. Errors in index data may occur from time to time and may not be identified and corrected for a period of time, and may have an adverse impact on the Fund and its shareholders.

Interest Rate Risk. An increase in interest rates may cause the value of fixed-income securities held by the Fund to decline.

Issuer Risk. Fund performance 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 securities to decline.

Liquidity Risk. Liquidity risk exists when particular investments are difficult to purchase or sell. This can reduce the Fund's returns because the Fund may be unable to transact at advantageous times or prices.

Management Risk. As the Fund may not fully replicate the Underlying Index, it is subject to the risk that BFA's investment strategy may not produce the intended results.

Market Risk. The Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns.

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 disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS, AMONG OTHERS, MAY LEAD TO THE FUND'S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

Non-Diversification Risk. The Fund may invest a large percentage of its assets in securities issued by or representing a small number of issuers. As a result, the Fund's performance may depend on the performance of a small number of issuers.

Passive Investment Risk. The Fund is not actively managed and BFA does not attempt to take defensive positions under any market conditions, including declining markets.

Prepayment Risk. During periods of falling interest rates, an issuer of mortgages and other securities may be able to repay principal prior to the security’s maturity, causing the Fund to have to reinvest in securities with a lower yield, resulting in a decline in the Fund’s income.

Risk of Investing in the United States. The Fund has significant exposure to United States issuers. 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.

Securities Lending Risk. The Fund may engage in securities lending. Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of the collateral provided for loaned securities or a decline in the value of any investments made with cash collateral. These events could also trigger adverse tax consequences for the Fund.

Tracking Error Risk. Tracking error is the divergence of the Fund’s performance from that of the Underlying Index. Tracking error may occur because of differences between the securities held in the Fund’s portfolio and those included in the Underlying Index, pricing differences, transaction costs, the Fund’s holding of cash, differences in timing of the accrual of distributions, changes to the Underlying Index or the need to meet various new or existing regulatory requirements. This risk may be heightened during times of increased market volatility or other unusual market conditions. Tracking error also may result because the Fund incurs fees and expenses, while the Underlying Index does not. BFA EXPECTS THAT THE FUND MAY EXPERIENCE HIGHER TRACKING ERROR THAN IS TYPICAL FOR SIMILAR INDEX EXCHANGE-TRADED FUNDS, ESPECIALLY BEFORE THE FUND REACHES SUFFICIENT SCALE AND FURTHER BROADENS ITS HOLDINGS.
Risk Lose Money [Text] rr_RiskLoseMoney 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.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. The Fund may invest a large percentage of its assets in securities issued by or representing a small number of issuers. As a result, the Fund's performance may depend on the performance of a small number of issuers.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance Information
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The bar chart and table that follow show how the Fund has performed on a calendar year basis and provide an indication of the risks of investing in the Fund. Both assume that all dividends and distributions have been reinvested in the Fund. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Supplemental information about the Fund’s performance is shown under the heading Total Return Information in the Supplemental Information section of the Prospectus. If BFA had not waived certain Fund fees during certain periods, the Fund's returns would have been lower.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table that follow show how the Fund has performed on a calendar year basis and provide an indication of the risks of investing in the Fund.
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 Year by Year Returns (Year Ended December 31)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock The best calendar quarter return during the period shown above was 1.02% in the 3rd quarter of 2013; the worst was -2.76% in the 2nd quarter of 2013.

Updated performance information is available at www.iShares.com or by calling 1-800-iShares (1-800-474-2737) (toll free).
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns
(for the periods ended December 31, 2013)
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 sale 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 Core GNMA Bond ETF | iShares Core GNMA Bond ETF
 
Risk/Return: rr_RiskReturnAbstract  
Management Fees rr_ManagementFeesOverAssets 0.15% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none [1]
Other Expenses rr_OtherExpensesOverAssets none [1]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04% [1]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.19% [1]
Fee Waivers rr_FeeWaiverOrReimbursementOverAssets (0.04%) [1]
Total Annual Fund Operating Expenses After Fee Waivers rr_NetExpensesOverAssets 0.15% [1]
1 Year rr_ExpenseExampleYear01 $ 15
3 Years rr_ExpenseExampleYear03 55
5 Years rr_ExpenseExampleYear05 101
10 Years rr_ExpenseExampleYear10 $ 236
2013 rr_AnnualReturn2013 (2.77%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel best
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2013
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 1.02%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel worst
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.76%)
One Year rr_AverageAnnualReturnYear01 (2.77%)
Since Fund Inception rr_AverageAnnualReturnSinceInception (0.91%)
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 14, 2012
iShares Core GNMA Bond ETF | Return After Taxes on Distributions | iShares Core GNMA Bond ETF
 
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (3.12%) [2]
Since Fund Inception rr_AverageAnnualReturnSinceInception (1.34%) [2]
iShares Core GNMA Bond ETF | Return After Taxes on Distributions and Sale of Fund Shares | iShares Core GNMA Bond ETF
 
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (1.57%) [2]
Since Fund Inception rr_AverageAnnualReturnSinceInception (0.85%) [2]
iShares Core GNMA Bond ETF | Barclays U.S. GNMA Bond Index (Index returns do not reflect deductions for fees, expenses, or taxes)
 
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (2.12%)
Since Fund Inception rr_AverageAnnualReturnSinceInception (0.20%)
[1] The expense information in the table above has been restated, as of the Fund's most recent fiscal year end, to reflect current fees.
[2] 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 sale 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.