v3.25.4
First Trust Enhanced Short Maturity ETF Investment Risks - First Trust Enhanced Short Maturity ETF
Oct. 31, 2025
Asset Backed Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] ASSET-BACKED SECURITIES RISK. Asset-backed securities are debt securities typically created by buying and pooling loans or other receivables other than mortgage loans and creating securities backed by those similar type assets. As with other debt securities, asset-backed securities are subject to credit risk, extension risk, interest rate risk, liquidity risk and valuation risk. These securities are generally not backed by the full faith and credit of the U.S. government and are subject to the risk of default on the underlying asset or loan, particularly during periods of economic downturn. The impairment of the value of collateral or other assets underlying an asset-backed security, such as a result of non-payment of loans or non-performance of underlying assets, may result in a reduction in the value of such asset-backed securities and losses to the Fund.
Authorized Participant Concentration Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] AUTHORIZED PARTICIPANT CONCENTRATION RISK. Only an authorized participant may engage in creation or redemption transactions directly with the Fund. A limited number of institutions act as authorized participants for the Fund. To the extent that these institutions exit the business or are unable to proceed with creation and/or redemption orders and no other authorized participant steps forward to create or redeem, the Fund’s shares may trade at a premium or discount (the difference between the market price of the Fund's shares and the Fund's net asset value) and possibly face delisting and the bid/ask spread (the difference between the price that someone is willing to pay for shares of the Fund at a specific point in time versus the price at which someone is willing to sell) on the Fund’s shares may widen.
Call Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CALL RISK. Some debt securities may be redeemed, or “called,” at the option of the issuer before their stated maturity date. In general, an issuer will call its debt securities if they can be refinanced by issuing new debt securities which bear a lower interest rate. The Fund is subject to the possibility that during periods of falling interest rates an issuer will call its high yielding debt securities. The Fund would then be forced to invest the proceeds at lower interest rates, likely resulting in a decline in the Fund’s income.
Cash Transactions Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CASH TRANSACTIONS RISK. The Fund will effect some or all of its creations and redemptions for cash rather than in-kind. As a result, an investment in the Fund may be less tax-efficient than an investment in an ETF that effects all of its creations and redemptions in-kind. Because the Fund may effect redemptions for cash, it may be required to sell portfolio securities in order to obtain the cash needed to distribute redemption proceeds. A sale of portfolio securities may result in capital gains or losses and may also result in higher brokerage costs.
CLO Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CLO RISK. CLOs bear many of the same risks as other forms of asset-backed securities, including credit risk, interest rate risk, liquidity risk and valuation risk. As they are backed by pools of loans, CLOs also bear similar risks to investing in loans directly. CLOs issue classes or “tranches” that vary in risk, expected maturity, priority of payment and yield. CLOs may experience substantial losses. Losses on underlying loans are typically borne first by the holders of subordinate tranches. Investment in CLOs may decrease in market value when the CLO experiences loan defaults or credit impairment, when the asset class broadly declines, or during periods of market anticipation of defaults and investor aversion to CLO securities as a class. Certain CLO tranches may contain underlying loans that are "payment-in-kind" assets, where interest is paid through the issuance of additional debt rather than cash, which could have negative effects on the performance of a CLO tranche.
Counterparty Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] COUNTERPARTY RISK. Fund transactions involving a counterparty are subject to the risk that the counterparty will not fulfill its obligation to the Fund. Counterparty risk may arise because of the counterparty’s financial condition (i.e., financial difficulties, bankruptcy, or insolvency), market activities and developments, or other reasons, whether foreseen or not. A counterparty’s inability to fulfill its obligation may result in significant financial loss to the Fund. The Fund may be unable to recover its investment from the counterparty or may obtain a limited recovery, and/or recovery may be delayed.
Credit Rating Agency Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CREDIT RATING AGENCY RISK. Credit ratings are determined by credit rating agencies such as S&P Global Ratings, Moody’s Investors Services, Inc. and Fitch Inc., and are only the opinions of such entities. Ratings assigned by a rating agency are not absolute standards of credit quality and do not evaluate market risk or the liquidity of securities. First Trust makes no warranty whatsoever regarding the ability of such ratings to accurately reflect the creditworthiness of an issuer. Any shortcomings, changes to or inefficiencies in credit rating agencies’ processes for determining credit ratings may adversely affect the credit ratings of securities held by the Fund or securities in which the Fund would otherwise invest and, as a result, may adversely affect those securities’ perceived or actual credit risk, as well as the Fund’s performance.
Credit Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CREDIT RISK. An issuer or other obligated party of a debt security may be unable or unwilling to make dividend, interest and/or principal payments when due. In addition, the value of a debt security may decline because of concerns about the issuer’s ability or unwillingness to make such payments.
Credit Spread Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CREDIT SPREAD RISK. From time to time, spreads (i.e., the difference in yield between debt securities that have different credit qualities or other differences) may increase, which may reduce the market value of some of the Fund’s debt securities. While the Fund may employ strategies to mitigate credit spread risk, these strategies may not be successful.
Current Market Conditions Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CURRENT MARKET CONDITIONS RISK. Current market conditions risk is the risk that a particular investment, or shares of the Fund in general, may fall in value due to current market conditions. As a means to fight inflation, the Federal Reserve and certain foreign central banks have raised interest rates; however, the Federal Reserve has begun to lower interest rates and may continue to do so. U.S. regulators have proposed several changes to market and issuer regulations which would directly impact the Fund, and any regulatory changes could adversely impact the Fund’s ability to achieve its investment strategies or make certain investments. Potential future bank failures could result in disruption to the broader banking industry or markets generally and reduce confidence in financial institutions and the economy as a whole, which may also heighten market volatility and reduce liquidity. Additionally, challenges in commercial real estate markets, including high interest rates, declining valuations and elevated vacancies, could have a broader impact on financial markets. The ongoing adversarial political climate in the United States, as well as political and diplomatic events both domestic and abroad, have and may continue to have an adverse impact the U.S. regulatory landscape, markets and investor behavior, which could have a negative impact on the Fund’s investments and operations. The change in administration resulting from the 2024 United States national elections could result in significant impacts to international trade relations, tax and immigration policies, and other aspects of the national and international political and financial landscape, which could affect, among other things, inflation and the securities markets generally. Other unexpected political, regulatory and diplomatic events within the U.S. and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy. For example, ongoing armed conflicts between Russia and Ukraine in Europe and among Israel, Iran, Hamas and other militant groups in the Middle East, have caused and could continue to cause significant market disruptions and volatility within the markets in Russia, Europe, the Middle East and the United States. The hostilities and sanctions resulting from those hostilities have and could continue to have a significant impact on certain Fund investments as well as Fund performance and liquidity. The economies of the United States and its trading partners, as well as the financial markets generally, may be adversely impacted by trade disputes, including the imposition of tariffs, and other matters. For example, the United States has imposed trade barriers and restrictions on China. In addition, the Chinese government is engaged in a longstanding dispute with Taiwan, continually threatening an invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt invading Taiwan, or if other geopolitical conflicts develop or worsen, economies, markets and individual securities may be adversely affected, and the value of the Fund’s assets may go down. A public health crisis and the ensuing policies enacted by governments and central banks may cause significant volatility and uncertainty in global financial markets, negatively impacting global growth prospects. As the COVID-19 global pandemic illustrated, such events may affect certain geographic regions, countries, sectors and industries more significantly than others. Advancements in technology may also adversely impact markets and the overall performance of the Fund. For instance, the economy may be significantly impacted by the advanced development and increased regulation of artificial intelligence. Additionally, cyber security breaches of both government and non-government entities could have negative impacts on infrastructure and the ability of such entities, including the Fund, to operate properly. These events, and any other future events, may adversely affect the prices and liquidity of the Fund’s portfolio investments and could result in disruptions in the trading markets.
Cyber Security Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CYBER SECURITY RISK. The Fund is susceptible to operational, information security and related risks through breaches in cyber security. A breach in cyber security refers to both intentional and unintentional events that may cause the Fund to lose proprietary information, suffer data corruption or lose operational capacity, any of which could result in a material adverse effect on the Fund or its shareholders. Such events could cause the Fund to incur regulatory penalties, reputational damage, additional compliance costs associated with corrective measures and/or financial loss. Cyber security breaches may involve unauthorized access to the Fund’s digital information systems through “hacking” or malicious software coding but may also result from outside attacks such as denial-of-service attacks through efforts to make network services unavailable to intended users. Emerging threats like ransomware or zero-day exploits could also cause disruptions to Fund operations. In addition, cyber security breaches of the issuers of securities in which the Fund invests or the Fund’s third-party service providers, such as its administrator, transfer agent, custodian, or sub-advisor, as applicable, among many other third-party service providers, can also subject the Fund to many of the same risks associated with direct cyber security breaches. Further, errors, misconduct, or compromise of accounts of employees of the Fund or its third-party service providers can also create material cybersecurity risks. Although the Fund has established risk management systems designed to reduce the risks associated with cyber security, there is no guarantee that such efforts will succeed, especially because the Fund does not directly control the cyber security systems of issuers or third-party service providers. Cyber security incidents may also trigger Fund obligations under data privacy laws, potentially increasing notification and compliance burdens. Cyber security incidents affecting issuers in whose securities the Fund invests may also have a negative impact on the value of the securities of such issuers, and in turn, the value of the Fund.
Debt Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] DEBT SECURITIES RISK. Investments in debt securities subject the holder to the credit risk of the issuer. Credit risk refers to the possibility that the issuer or other obligor of a security will not be able or willing to make payments of interest and principal when due. Generally, the value of debt securities will change inversely with changes in interest rates. To the extent that interest rates rise, certain underlying obligations may be paid off substantially slower than originally anticipated and the value of those securities may fall sharply. During periods of falling interest rates, the income received by the Fund may decline. If the principal on a debt security is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. Debt securities generally do not trade on a securities exchange making them generally less liquid and more difficult to value than common stock. Debt securities held by the Fund may be subject to amendments, waivers, or exchange offers that modify their terms. These transactions may be initiated by borrowers to address financial stress and may include exchanges of existing debt securities for new instruments with different priority, collateral, or economic characteristics. Participation in, or exclusion from, such transactions could result in the Fund holding debt that is structurally or contractually subordinated, less liquid, or of lower market value than prior to the transaction.
Extension Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] EXTENSION RISK. Extension risk is the risk that, when interest rates rise, certain obligations will be paid off by the issuer (or other obligated party) more slowly than anticipated, causing the value of these debt securities to fall. Rising interest rates tend to extend the duration of debt securities, making their market value more sensitive to changes in interest rates. The value of longer-term debt securities generally changes more in response to changes in interest rates than shorter-term debt securities. As a result, in a period of rising interest rates, securities may exhibit additional volatility and may lose value.
Financial Companies Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] FINANCIAL COMPANIES RISK. Financial companies, such as retail and commercial banks, insurance companies and financial services companies, are especially subject to the adverse effects of economic recession, currency exchange rates, extensive government regulation, decreases in the availability of capital, volatile interest rates, portfolio concentrations in geographic markets, industries or products (such as commercial and residential real estate loans), competition from new entrants and blurred distinctions in their fields of business.
Floating Rate Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] FLOATING RATE SECURITIES RISK. Floating rate securities are structured so that the security’s coupon rate fluctuates based upon the level of a reference rate. As a result, the coupon on floating rate securities will generally decline in a falling interest rate environment, causing the Fund to experience a reduction in the income it receives from the security. A floating rate security’s coupon rate resets periodically according to the terms of the security. Consequently, in a rising interest rate environment, floating rate securities with coupon rates that reset infrequently may lag behind the changes in market interest rates. Floating rate securities may also contain terms that impose a maximum coupon rate the issuer will pay, regardless of the level of the reference rate which would decrease the value of the security.
Income Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] INCOME RISK. The Fund’s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.
Index Or Model Constituent Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] INDEX OR MODEL CONSTITUENT RISK. The Fund may be a constituent of one or more indices or ETF models. As a result, the Fund may be included in one or more index-tracking exchange-traded funds or mutual funds. Being a component security of such a vehicle could greatly affect the trading activity involving the Fund’s shares, the size of the Fund and the market volatility of the Fund. Inclusion in an index could increase demand for the Fund and removal from an index could result in outsized selling activity in a relatively short period of time. As a result, the Fund’s net asset value could be negatively impacted and the Fund’s market price may be below the Fund’s net asset value during certain periods. In addition, index rebalances may potentially result in increased trading activity in the Fund's shares.
Inflation Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] INFLATION RISK. Inflation risk is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the present value of the Fund’s assets and distributions may decline.
Interest Rate Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] INTEREST RATE RISK. Interest rate risk is the risk that the value of the debt securities in the Fund’s portfolio will decline because of rising market interest rates. Interest rate risk is generally lower for shorter term debt securities and higher for longer-term debt securities. The Fund may be subject to a greater risk of rising interest rates than would normally be the case during periods of low interest rates. Duration is a reasonably accurate measure of a debt security’s price sensitivity to changes in interest rates and a common measure of interest rate risk. Duration measures a debt security’s expected life on a present value basis, taking into account the debt security’s yield, interest payments and final maturity. In general, duration represents the expected percentage change in the value of a security for an immediate 1% change in interest rates. For example, the price of a debt security with a three-year duration would be expected to drop by approximately 3% in response to a 1% increase in interest rates. Therefore, prices of debt securities with shorter durations tend to be less sensitive to interest rate changes than debt securities with longer durations. Higher sensitivity to interest rates is generally correlated with higher levels of volatility and, therefore, greater risk. As the value of a debt security changes over time, so will its duration.
Investment Companies Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] INVESTMENT COMPANIES RISK. The Fund may invest in securities of other investment companies. As a shareholder in another investment company, the Fund will bear its ratable share of that investment company’s expenses, and would remain subject to payment of the Fund’s advisory and administrative fees with respect to assets so invested. Shareholders would therefore be subject to duplicative expenses to the extent the Fund invests in other investment companies. In addition, the Fund will incur brokerage costs when purchasing and selling shares of ETFs or other exchange-traded investment companies.
Liquidity Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] LIQUIDITY RISK. The Fund may hold certain investments that may be subject to restrictions on resale, trade over-the-counter or in limited volume, or lack an active trading market. Accordingly, the Fund may not be able to sell or close out of such investments at favorable times or prices (or at all), or at the prices approximating those at which the Fund currently values them. Illiquid securities may trade at a discount from comparable, more liquid investments and may be subject to wide fluctuations in market value.
Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] MANAGEMENT RISK. The Fund is subject to management risk because it is an actively managed portfolio. In managing the Fund’s investment portfolio, the portfolio managers will apply investment techniques and risk analyses that may not produce the desired result. There can be no guarantee that the Fund will meet its investment objective.
Market Maker Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] MARKET MAKER RISK. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares due to a limited number of market makers. Decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund’s portfolio securities and the Fund’s market price. The Fund may rely on a small number of third-party market makers to provide a market for the purchase and sale of shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund’s net asset value and the price at which the Fund’s shares are trading on the Exchange, which could result in a decrease in value of the Fund’s shares. This reduced effectiveness could result in Fund shares trading at a discount to net asset value and also in greater than normal intraday bid-ask spreads for Fund shares.
Market Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] MARKET RISK. Market risk is the risk that a particular investment, or shares of the Fund in general, may fall in value. Securities are subject to market fluctuations caused by real or perceived adverse economic, political, and regulatory factors or market developments, changes in interest rates and perceived trends in securities prices. Shares of the Fund could decline in value or underperform other investments. In addition, local, regional or global events such as war, acts of terrorism, market manipulation, government defaults, government shutdowns, regulatory actions, political changes, diplomatic developments, the imposition of sanctions and other similar measures, spread of infectious diseases or other public health issues, recessions, natural disasters, or other events could have a significant negative impact on the Fund and its investments. Any of such circumstances could have a materially negative impact on the value of the Fund’s shares, the liquidity of an investment, and may result in increased market volatility. During any such events, the Fund’s shares may trade at increased premiums or discounts to their net asset value, the bid/ask spread on the Fund’s shares may widen and the returns on investment may fluctuate.
Money Market Short Term Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] MONEY MARKET/SHORT-TERM SECURITIES RISK. To the extent that the Fund invests in money market or short-term securities, the Fund may be subject to certain risks associated with such investments. An investment in a money market fund or short-term securities is not a bank deposit and is not insured or guaranteed by any bank, the Federal Deposit Insurance Corporation or any other government agency. It is possible for the Fund to lose money by investing in money market funds. A money market fund may not achieve its investment objective. Changes in government regulations may affect the value of an investment in a money market fund.
Mortgage Related Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] MORTGAGE-RELATED SECURITIES RISK. Mortgage-related securities are subject to the same risks as investments in other types of debt securities, including credit risk, interest rate risk, liquidity risk and valuation risk. However, these investments make the Fund more susceptible to adverse economic, political or regulatory events that affect the value of real estate. Mortgage-related securities are also significantly affected by the rate of prepayments and modifications of the mortgage loans underlying those securities, as well as by other factors such as borrower defaults, delinquencies, realized or liquidation losses and other shortfalls. The incidence of borrower defaults or delinquencies may rise significantly during financial downturns and could adversely affect the value of mortgage-related securities held by the Fund. Events such as war, acts of terrorism, spread of infectious diseases or other public health issues, recessions, or other events that result in broad and simultaneous financial hardships for individuals and businesses could have a significant negative impact on the value of mortgage-related securities. Mortgage-related securities are particularly sensitive to prepayment risk and extension risk, given that mortgage loans generally allow borrowers to refinance. In periods of declining interest rates, borrowers may be more apt to prepay their mortgage sooner than expected. This can reduce the returns to the security holder as the amount of interest related to the price may be reduced while the proceeds may have to be reinvested at lower prevailing interest rates. This is prepayment risk. In periods of rising interest rates, borrowers may be less likely to refinance than expected thus extending the cash flows of the security such that there is increased downward price sensitivity to interest rate changes. This is extension risk. As the timing and amount of prepayments cannot be accurately predicted, the timing of changes in the rate of prepayments of the mortgage loans may significantly affect the Fund's actual yield to maturity on any mortgage-related securities. Along with prepayment risk, mortgage-related securities are significantly affected by interest rate risk.
Municipal Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] MUNICIPAL SECURITIES RISK. Issuers, including governmental issuers, may be unable to pay their obligations as they come due. The values of municipal securities that depend on a specific revenue source to fund their payment obligations may fluctuate as a result of actual or anticipated changes in the cash flows generated by the revenue source or changes in the priority of the municipal obligation to receive the cash flows generated by the revenue source. The values of municipal securities held by the Fund may be adversely affected by local political and economic conditions and developments. Adverse conditions in an industry significant to a local economy could have a correspondingly adverse effect on the financial condition of local issuers. In addition, income from municipal securities held by the Fund could be declared taxable because of, among other things, unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or noncompliant conduct of an issuer or other obligated party. Loss of tax-exempt status may cause interest received and distributed to shareholders by the Fund to be taxable and may result in a significant decline in the values of such municipal securities. Due to the COVID-19 pandemic, the risks of the municipal securities market have been magnified. The costs associated with combating the pandemic and the negative impact on tax revenues has adversely affected the financial condition of many states and political subdivisions. These risks may also adversely affect several sectors of the municipal bond market, such as airports, toll roads, hospitals and colleges, among many others. The full impact of the COVID-19 pandemic on state and political subdivisions’ ability to make payments on debt obligations is impossible to predict, but could negatively impact the value of bonds, the ability of state and political subdivisions to make payments when due and the performance of the Fund.
Non Agency Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] NON-AGENCY SECURITIES RISK. Investments in asset-backed or mortgage-backed securities offered by non-governmental issuers, such as commercial banks, savings and loans, private mortgage insurance companies, mortgage bankers and other secondary market issuers are subject to additional risks. There are no direct or indirect government or agency guarantees of payments in loan pools created by non-government issuers. Securities issued by private issuers are subject to the credit risks of the issuers. An unexpectedly high rate of defaults on the loan pool may adversely affect the value of a non-agency security and could result in losses to the Fund. The risk of such defaults is generally higher in the case of pools that include subprime loans. Non-agency securities are typically traded “over-the-counter” rather than on a securities exchange and there may be a limited market for the securities, especially when there is a perceived weakness in the mortgage and real estate market sectors. Without an active trading market, the non-agency mortgage-related securities held by the Fund may be particularly difficult to value because of the complexities involved in assessing the value of the underlying loans and the value of these securities can change dramatically over time.
Non US Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] NON-U.S. SECURITIES RISK. Non-U.S. securities are subject to higher volatility than securities of domestic issuers due to possible adverse political, social or economic developments, restrictions on foreign investment or exchange of securities, capital controls, lack of liquidity, currency exchange rates, excessive taxation, government seizure of assets, the imposition of sanctions by foreign governments, different legal or accounting standards, and less government supervision and regulation of securities exchanges in foreign countries.
Operational Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] OPERATIONAL RISK. The Fund is subject to risks arising from various operational 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. These errors or failures may adversely affect the Fund’s operations, including its ability to execute its investment process, calculate or disseminate its NAV or intraday indicative optimized portfolio value in a timely manner, and process creations or redemptions. The Fund relies on third-parties for a range of services, including custody, valuation, administration, transfer services, securities lending and accounting, among many others. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund’s ability to meet its investment objective. Although the Fund and the Fund's investment advisor seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.
Premium Discount Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] PREMIUM/DISCOUNT RISK. The market price of the Fund’s shares will generally fluctuate in accordance with changes in the Fund’s net asset value as well as the relative supply of and demand for shares on the Exchange. The Fund’s investment advisor cannot predict whether shares will trade below, at or above their net asset value because the shares trade on the Exchange at market prices and not at net asset value. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their net asset value), the Fund’s investment advisor believes that large discounts or premiums to the net asset value of shares should not be sustained. During stressed market conditions, the market for the Fund’s shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying portfolio holdings, which could in turn lead to differences between the market price of the Fund’s shares and their net asset value and the bid/ask spread on the Fund’s shares may widen.
Prepayment Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] PREPAYMENT RISK. Prepayment risk is the risk that the issuer of a debt security will repay principal prior to the scheduled maturity date. Debt securities allowing prepayment may offer less potential for gains during a period of declining interest rates, as the Fund may be required to reinvest the proceeds of any prepayment at lower interest rates. These factors may cause the value of an investment in the Fund to change.
Significant Exposure Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] SIGNIFICANT EXPOSURE RISK. To the extent that the Fund invests a significant percentage of its assets in a single asset class or the securities of issuers within the same country, state, region, industry or sector, an adverse economic, business or political development may affect the value of the Fund’s investments more than if the Fund were more broadly diversified. A significant exposure makes the Fund more susceptible to any single occurrence and may subject the Fund to greater market risk than a fund that is more broadly diversified.
Sovereign And Quasi Sovereign Debt Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] SOVEREIGN AND QUASI-SOVEREIGN DEBT SECURITIES RISK. Sovereign debt securities that are issued or guaranteed by foreign governmental entities. Investments in such securities are subject to the risk that the relevant sovereign government or governmental entity may delay or refuse to pay interest or repay principal on its debt. Such delays or refusals may be due to cash flow problems, insufficient foreign currency reserves, political considerations, the size of its debt relative to the economy or the failure to put in place economic reforms required by the International Monetary Fund or other multilateral agencies. There is no legal process for collecting sovereign debt that is not repaid, nor are there bankruptcy proceedings through which all or part of the unpaid sovereign debt may be collected.
Trading Issues Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] TRADING ISSUES RISK. Trading in Fund shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange’s “circuit breaker” rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund’s assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.
US Government Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] U.S. GOVERNMENT SECURITIES RISK. U.S. government securities are subject to interest rate risk but generally do not involve the credit risks associated with investments in other types of debt securities. As a result, the yields available from U.S. government securities are generally lower than the yields available from other debt securities. U.S. government securities are guaranteed only as to the timely payment of interest and the payment of principal when held to maturity.
Valuation Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] VALUATION RISK. The sale price the Fund could receive for a security may differ from the Fund’s valuation of the security, particularly for securities that trade in low volume or volatile markets or that are valued using a fair value methodology. Unlike publicly traded securities that trade on national securities exchanges, there is no central place or exchange for trading most debt securities. Debt securities generally trade on an “over-the-counter” market. Due to the lack of centralized information and trading, and variations in lot sizes of certain debt securities, the valuation of debt securities may carry more uncertainty and risk than that of publicly traded securities. Debt securities are commonly valued by third-party pricing services that utilize a range of market-based inputs and assumptions, including readily available market quotations obtained from broker-dealers making markets in such securities, cash flows and transactions for comparable instruments. However, because the available information is less reliable and more subjective, elements of judgment may play a greater role in valuation of debt securities than for other types of securities. Different pricing services may incorporate different assumptions and inputs into their valuation methodologies, potentially resulting in different values for the same securities. As a result, if the Advisor were to change its valuation policies, or if the Fund were to change pricing services, or if a pricing service were to change its valuation methodology, there could be a material impact, either positive or negative, on the Fund’s net asset value. Additionally, pricing services generally price debt securities assuming orderly transactions of an institutional “round lot” size, but some trades may occur in smaller, “odd lot” sizes, often at lower prices than institutional round lot trades. There is no assurance that the Fund will be able to sell a portfolio security at the price established by the pricing service, which could result in a loss to the Fund. In addition, the value of the debt securities in the Fund's portfolio may change on days or during time periods when shareholders will not be able to purchase or sell the Fund's shares. Authorized Participants who purchase or redeem Fund shares on days when the Fund is holding fair-valued securities may receive fewer or more shares, or lower or higher redemption proceeds, than they would have received had the Fund not fair-valued securities or used a different valuation methodology. Net asset value calculation may also be impacted by operational risks arising from factors such as failures in systems and technology.
Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] You could lose money by investing in the Fund.
Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.