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First Trust SSI Strategic Convertible Securities ETF Investment Risks - First Trust SSI Strategic Convertible Securities ETF
Oct. 31, 2025
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.
BDC Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] BDC RISK. A BDC may invest in the equity and fixed income securities of smaller and developing companies as well as companies that are experiencing financial crises. Investments in these types of companies present a greater risk of loss due to the companies’ youth and limited track records. They are also generally more susceptible to competition and economic and market changes due to limited products and market shares. In addition, the securities of smaller and developing companies and companies experiencing financial crises typically have limited liquidity. These companies may also have limited capital resources, meaning that they present a greater risk of default on fixed income securities issued and of non-payment of dividends on any preferred and common stock issued. A BDC may use leverage (e.g., borrowing and the issuance of fixed income and preferred securities) to finance its own operations and may suffer significant losses if market fluctuations cause the BDC’s net asset value to decline or if related interest charges exceed investment income. The Fund has no control over the investments made by BDCs, and BDCs are subject to additional risks such as the fact that their shares may trade at a market price above or below their net asset value and that an active market may not develop for their shares.
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.
Contingent Convertible Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CONTINGENT CONVERTIBLE SECURITIES RISK. CoCos are hybrid securities most commonly issued by banking institutions that present risks similar to debt securities and convertible securities. CoCos are distinct in that they are intended to either convert into equity or have their principal written down upon the occurrence of certain “triggers.” When an issuer’s capital ratio falls below a specified trigger level, or in a regulator’s discretion depending on the regulator’s judgment about the issuer’s solvency prospects, a CoCo may be written down, written off or converted into an equity security. Due to the contingent write-down, write-off and conversion feature, CoCos may have substantially greater risk than other securities in times of financial stress. If the trigger level is breached, the issuer's decision to write down, write off or convert a CoCo may be outside its control, and the Fund may suffer a complete loss on an investment in CoCos with no chance of recovery even if the issuer remains in existence. The value of CoCos is unpredictable and may be influenced by many factors including, without limitation: the creditworthiness of the issuer and/or fluctuations in such issuer's applicable capital ratios; supply and demand for CoCos; general market conditions and available liquidity; and economic, financial and political events that affect the issuer, its particular market or the financial markets in general.
Convertible Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] CONVERTIBLE SECURITIES RISK. A convertible security has characteristics of both equity and debt securities and, as a result, is exposed to risks that are typically associated with both types of securities. The value of convertible securities may rise and fall with the market value of the underlying stock or, like a debt security, vary with changes in interest rates and the credit quality of the issuer. A convertible security tends to perform more like a stock when the underlying stock price is high relative to the conversion price and more like a debt security when the underlying stock price is low relative to the conversion price.
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.
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.
Depositary Receipts Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] DEPOSITARY RECEIPTS RISK. Depositary receipts may be less liquid than the underlying shares in their primary trading market. Any distributions paid to the holders of depositary receipts are usually subject to a fee charged by the depositary. Holders of depositary receipts may have limited voting rights, and investment restrictions in certain countries may adversely impact the value of depositary receipts because such restrictions may limit the ability to convert the equity shares into depositary receipts and vice versa. Such restrictions may cause the equity shares of the underlying issuer to trade at a discount or premium to the market price of the depositary receipts.
Equity Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] EQUITY SECURITIES RISK. The value of the Fund's shares will fluctuate with changes in the value of the equity securities in which it invests. Equity securities prices fluctuate for several reasons, including changes in investors’ perceptions of the financial condition of an issuer or the general condition of the relevant equity market, such as market volatility, or when political or economic events affecting an issuer occur. Common stock prices may be particularly sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase. Equity securities may decline significantly in price over short or extended periods of time, and such declines may occur in the equity market as a whole, or they may occur in only a particular country, company, industry or sector of the market.
ETN Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] ETN RISK. ETNs are unsecured debt obligations. As such, ETNs are subject to the credit risk of the issuer, and the value of an ETN may drop due to a downgrade in the issuer’s credit rating, despite the ETN’s underlying market benchmark or assets remaining unchanged. The value of an ETN may also be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in the underlying market, changes in the applicable interest rates, and economic, legal, political, or geographic events that affect the referenced underlying market or assets. ETNs are also subject to the risk that the other party to the contract will not fulfill its contractual obligations, which may cause losses or additional costs to the Fund. When the Fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. While ETNs are exchange-traded, a trading market may not develop, limiting liquidity and adversely affecting the market value of the ETN. Lastly, ETNs are not registered as investment companies under the 1940 Act. Consequently, holders of ETNs, including the Fund, do not have the regulatory protections provided to investors in registered investment companies.
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.
High Yield Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] HIGH YIELD SECURITIES RISK. High yield securities, or “junk” bonds, are subject to greater market fluctuations, are less liquid and provide a greater risk of loss than investment grade securities, and therefore, are considered to be highly speculative. In general, high yield securities may have a greater risk of default than other types of securities and could cause income and principal losses for the Fund.
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.
Information Technology Companies Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] INFORMATION TECHNOLOGY COMPANIES RISK. Information technology companies produce and provide hardware, software and information technology systems and services. These companies may be adversely affected by rapidly changing technologies, short product life cycles, fierce competition, aggressive pricing and reduced profit margins, the loss of patent, copyright and trademark protections, cyclical market patterns, evolving industry standards and frequent new product introductions. In addition, information technology companies are particularly vulnerable to federal, state and local government regulation, and competition and consolidation, both domestically and internationally, including competition from foreign competitors with lower production costs. Information technology companies also heavily rely on intellectual property rights and may be adversely affected by the loss or impairment of those rights.
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.
Large Capitalization Companies Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] LARGE CAPITALIZATION COMPANIES RISK. Large capitalization companies may grow at a slower rate and be less able to adapt to changing market conditions than smaller capitalization companies. Thus, the return on investment in securities of large capitalization companies may be less than the return on investment in securities of small and/or mid capitalization companies. The performance of large capitalization companies also tends to trail the overall market during different market cycles.
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. Certain investments held by the Fund that trade on non-U.S. exchanges may be further subject to liquidity risk due to foreign market closures or unexpected impediments to trading on local markets. 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.
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.
Portfolio Turnover Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] PORTFOLIO TURNOVER RISK. High portfolio turnover may result in the Fund paying higher levels of transaction costs and may generate greater tax liabilities for shareholders. Portfolio turnover risk may cause the Fund’s performance to be less than expected.
Preferred Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] PREFERRED SECURITIES RISK. Preferred securities combine some of the characteristics of both common stocks and bonds. Preferred securities are typically subordinated to bonds and other debt securities in a company’s capital structure in terms of priority to corporate income, subjecting them to greater credit risk than those debt securities. Generally, holders of preferred securities have no voting rights with respect to the issuing company unless preferred dividends have been in arrears for a specified number of periods, at which time the preferred security holders may obtain limited rights. In certain circumstances, an issuer of preferred securities may defer payment on the securities and, in some cases, redeem the securities prior to a specified date. Preferred securities may also be substantially less liquid than other securities, including common stock.
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.
Restricted Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] RESTRICTED SECURITIES RISK. Restricted securities are securities that cannot be offered for public resale unless registered under the applicable securities laws or that have a contractual restriction that prohibits or limits their resale. The Fund may be unable to sell a restricted security on short notice or may be able to sell them only at a price below current value.
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.
Smaller Companies Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] SMALLER COMPANIES RISK. Small and/or mid capitalization companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than larger, more established companies as a result of several factors, including limited trading volumes, fewer products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than larger, more established companies.
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.
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. The Fund may hold securities or other assets that may be valued on the basis of factors other than market quotations. This may occur because the asset or security does not trade on a centralized exchange, or in times of market turmoil or reduced liquidity. There are multiple methods that can be used to value a portfolio holding when market quotations are not readily available. Fund investments that trade on non-U.S. exchanges that close prior to the close of the NYSE may be fair valued using a systematic fair valuation model. If these foreign investments meet certain criteria in relation to the valuation model, their valuation is systematically adjusted to reflect the impact of movement in the U.S. market after the close of certain foreign markets. The value established for any portfolio holding at a point in time might differ from what would be produced using a different methodology or if it had been priced using market quotations. In addition, there is no assurance that the Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that the Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time. The Fund’s ability to value investments may be impacted by technological issues or errors by pricing services or other third-party service providers.
Warrants And Rights Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] WARRANTS AND RIGHTS RISK. Warrants and rights do not carry with them the right to dividends or voting rights with respect to the securities that they entitle their holder to purchase, and they do not represent any rights in the assets of the issuer. As a result, warrants and rights may be considered more speculative than certain other types of investments. In addition, the value of a warrant or right does not necessarily change with the value of the underlying securities. The Fund could lose the value of a warrant or right if the right to subscribe to additional shares is not exercised prior to the warrant’s or right’s expiration date. The market for warrants and rights may be very limited and there may at times not be a liquid secondary market for warrants and rights.
Zero Coupon Bond Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] ZERO COUPON BOND RISK. The Fund may invest in zero coupon bonds. Zero coupon bonds do not pay interest on a current basis and may be highly volatile as interest rates rise or fall. Although zero coupon bonds generate income for accounting purposes, they do not produce cash flow, and thus an underlying fund could be forced to liquidate securities at an inopportune time in order to generate cash to distribute to shareholders as required by tax laws.
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.