Class K [Member] Investment Risks - Class K - iShares Short-Term TIPS Bond Index Fund |
Dec. 31, 2025 |
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| U S Treasury Obligations Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ U.S. Treasury Obligations Risk — U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s U.S. Treasury obligations to decline. |
| Inflation Indexed Bonds Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Inflation-Indexed Bonds Risk — The principal value of an investment in the Fund is not protected or otherwise guaranteed by virtue of any investments by the Fund in inflation-indexed bonds. The value of inflation-indexed securities generally fluctuates with changes in real interest rates, decreasing when real interest rates rise and increasing when real interest rates fall. Real interest rates represent nominal (or stated) interest rates minus the inflation rates. If the Fund purchases TIPS in the secondary market and the bonds’ principal values previously were adjusted upward, but then there is a period of declining inflation rates, the Fund may receive at maturity less than it invested. In addition, interest payments on inflation-indexed securities generally vary up or down along with the rate of inflation, and inflation-indexed bonds typically have lower nominal yields than conventional fixed-rate bonds. If the index measuring inflation falls, the principal value of inflation-indexed bonds will be adjusted downward, and consequently the interest payable on these securities (calculated with respect to a smaller principal amount) will be reduced. Any increase in the principal amount of an inflation-indexed bond will be considered taxable ordinary income, even though investors do not receive their principal until maturity. Periodic adjustments for inflation to the principal amount of an inflation-indexed bond may give rise to original issue discount, which will be includable in the Fund’s gross income. Due to original issue discount, the Fund may be required to make annual distributions to shareholders that exceed the cash received, which may cause the Fund to liquidate certain investments when it is not advantageous to do so. Also, if the principal value of an inflation-indexed bond is adjusted downward due to deflation, amounts previously distributed in the taxable year may be characterized in some circumstances as a return of capital.
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| Index Related Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Index-Related Risk — The index provider may rely on various sources of information to assess the criteria of components of the Underlying Index, including information that may be based on assumptions and estimates. Neither the Fund nor BlackRock can offer assurances that the index provider’s methodology or sources of information will provide an accurate assessment of included components. Errors in index data, index computations or the construction of the Underlying Index in accordance with its methodology may occur, and the index provider may not identify or correct them promptly or at all, which may have an adverse impact on the Fund and its shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political unrest or war) may impact the index provider or a third-party data provider and could cause the index provider to postpone a scheduled rebalance. This could cause the Underlying Index to vary from its normal or expected composition. |
| Passive Investment Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Passive Investment Risk — Because BlackRock does not select individual companies in the index that the Fund tracks, the Fund may hold securities of companies that present risks that an investment adviser researching individual securities might seek to avoid. |
| Tracking Error Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Tracking Error Risk — The Fund is subject to the risk of “tracking error,” which is the divergence of the Fund’s performance from that of the Underlying Index. Tracking error may occur due to a number of factors, including differences between the securities and other assets held in the Fund’s portfolio and those included in the Underlying Index; differences in the timing and methodologies used to value securities and other assets; transaction costs and other expenses incurred by the Fund that the Underlying Index does not incur; the Fund’s holding of uninvested cash; differences in the timing of the accrual or the valuation of dividends or interest received by the Fund or distributions paid to Fund shareholders; tax gains or losses; differences between the amount and/or timing of withholding taxes on dividends reflected in the Underlying Index from the Fund’s obligation, if any, for foreign withholding taxes; the requirements for the Fund to maintain pass-through tax treatment; portfolio transactions carried out to minimize the distribution of capital gains to shareholders; changes to the Underlying Index, such as during a rebalancing or reconstitution; and impacts to the Fund of complying with certain regulatory requirements or limits. A fund that tracks an index composed of a large number of securities or other assets may experience greater tracking error than a fund that tracks a more narrow index. Tracking error risk may be heightened during times of increased market volatility or other unusual market conditions. |
| Representative Sampling Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Representative Sampling Risk — Representative sampling is a method of indexing that involves investing in a representative sample of securities that collectively have a similar investment profile to the Underlying Index and resemble the Underlying Index in terms of risk factors and other key characteristics. The Fund may or may not hold every security in the Underlying Index. When the Fund deviates from a full replication indexing strategy to utilize a representative sampling strategy, the Fund is subject to an increased risk of tracking error, in that the securities selected in the aggregate for the Fund may not have an investment profile similar to those of the Underlying Index. |
| Asset Class Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Asset Class Risk — The securities and other assets or financial instruments in the Underlying Index or in the Fund’s portfolio may underperform in comparison to financial markets generally, a particular financial market, another index, or other asset classes. |
| Income Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Income Risk — The Fund’s income may decline due to a decline in inflation, deflation or changes in inflation expectations. |
| Interest Rate Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ 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 the Fund’s performance. During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns or pay dividends to shareholders.
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| Issuer Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ 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. |
| Management Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Management Risk — As the Fund may not fully replicate the Underlying Index, it is subject to the risk that BlackRock’s investment strategy may not produce the intended results. |
| Market Risk and Selection Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a security or other asset may decline due to changes in general market conditions, economic trends or events that are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its investments. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. |
| Operational and Technology Risks [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Operational and Technology Risks — The Fund is directly and indirectly susceptible to operational and technology risks, including those related to human errors, processing errors, communication errors, systems failures, cybersecurity incidents, and the use of artificial intelligence and machine learning (“AI”), which may result in losses for the Fund and its shareholders or may impair the Fund’s operations. While the Fund’s service providers are required to have appropriate operational, information security and cybersecurity risk management policies and procedures, their methods of risk management may differ from those of the Fund. Operational and technology risks for the issuers in which the Fund invests could also result in material adverse consequences for such issuers and may cause the Fund’s investments in such issuers to lose value. |
| Risk of Investing in the United States [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ Risk of Investing in the United States — 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. |
| TIPS Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ◼ TIPS Risk —The interest rate on TIPS is fixed at issuance, but over the life of the bond this interest may be paid on an increasing or decreasing principal value that has been adjusted for inflation. Although repayment of the original bond principal upon maturity is guaranteed, the market value of TIPS is not guaranteed, and will fluctuate. |
| Risk Lose Money [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. |
| Risk Not Insured Depository Institution [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. |