The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. For the most recent fiscal period, the Fund’s portfolio turnover rate was 35.11% of the average value of its portfolio.

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You will also incur usual and customary brokerage commissions when buying and selling Shares.

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. This example does not take into account customary brokerage commissions that you pay when purchasing or selling shares of the Fund in the secondary market.

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGIES

Strategy Portfolio Concentration [Text]

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The Fund concentrates its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. As of January 31, 2018, the Fund was concentrated in the energy sector.

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments. There is no guarantee that the Fund will achieve its investment objective. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund's net asset value ("NAV"), trading price, yield, total return and ability to meet its investment objective, as well as other risks that are described in greater detail in the Additional Information About the Funds section of this Prospectus and in the Statement of Additional Information ("SAI").

Asset Class Risk: Securities in the Underlying Index or otherwise held in the Fund's portfolio may underperform in comparison to the general securities markets or other asset classes.

Asset Fluctuation Risk: Certain shareholders, including an Authorized Participant (as defined in the SAI), the Adviser or an affiliate of the Adviser, may own a substantial amount of the Fund’s Shares. Additionally, from time to time an Authorized Participant, a third party investor, the Adviser, or an affiliate of the Adviser may invest in the Fund and hold its investment for a specific period of time in order to facilitate commencement of the Fund’s operations or to allow the Fund to achieve size or scale. Redemptions by large shareholders could have a significant negative impact on the Fund. If a large shareholder were to redeem all, or a large portion, of its Shares, there is no guarantee that the Fund will be able to maintain sufficient assets to continue operations, in which case the Board of Trustees may determine to liquidate the Fund. In addition, transactions by large shareholders may account for a large percentage of the trading volume on a national securities exchange and may, therefore, have a material upward or downward effect on the market price of the Shares.

Authorized Participant Concentration Risk: The Fund has a limited number of financial institutions that may act as Authorized Participants. Only Authorized Participants who have entered into agreements with the Fund’s distributor may engage in creation or redemption transactions directly with the Fund. To the extent that those Authorized Participants exit the business or are unable to process creation and/or redemption orders, and no other Authorized Participant is able to step forward to create or redeem in either of those cases, Shares may be more likely to trade at a premium or discount to NAV, and possibly face trading halts and/or delisting from a securities exchange. The Authorized Participant Concentration Risk may be heightened because the Fund invests in non-U.S. securities.

Cash Transaction Risk: Unlike many exchange-traded funds ("ETFs"), the Fund intends to effect primarily all creations and redemptions principally for cash, rather than in-kind securities. As a result, an investment in the Fund may be less tax-efficient than an investment in a more conventional ETF.

Concentration Risk: Because the Fund's investments are concentrated in the energy sector, the Fund will be susceptible to loss due to adverse occurrences affecting this sector or industry. To the extent that the Underlying Index concentrates in the securities of issuers in a particular country, industry, market, asset class, or sector, the Fund will also concentrate its investments to approximately the same extent. By concentrating its investments in a country, industry, market, asset class, or sector, the Fund faces more risks than if it were diversified broadly over numerous countries, industries, markets, asset classes, or sectors. Such risks, any of which may adversely affect the companies in which the Fund invests, may include, but are not limited to, the following: general economic conditions or cyclical market patterns that could negatively affect supply and demand; competition for resources; adverse labor relations; political or world events; obsolescence of technologies; and increased competition or new product introductions that may affect the profitability or viability of companies in a sector or industry. In addition, at times, such country, industry, market, asset class, or sector may be out of favor and underperform other sectors or industries or the market as a whole. For additional details on these risks, please see Risks Related to Investing in the Energy Sector.

Cyber Security Risk: Failures or breaches of the electronic systems of the Fund, the Adviser, and the Fund's other service providers, market makers, Authorized Participants or the issuers of securities in which the Fund invests have the ability to cause disruptions and negatively impact the Fund's business operations, potentially resulting in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cyber security plans and systems of the Fund's service providers, market makers, Authorized Participants or issuers of securities in which the Fund invests.

Equity Securities Risk: Equity securities are subject to changes in value and their values may be more volatile than other asset classes, as a result of such factors as a company’s business performance, investor perceptions, stock market trends and general economic conditions.

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

Industry Specific Risks: MLPs operating in the energy sector are also subject to risks specific to the industry they serve.

Midstream. Midstream MLPs that provide crude oil, refined product and natural gas services are subject to supply and demand fluctuations in the markets they serve, which may be impacted by a wide range of factors, including fluctuating commodity prices, weather, increased conservation or use of alternative fuel sources, increased governmental or environmental regulation, depletion, rising interest rates, declines in domestic or foreign production, accidents or catastrophic events, increasing operating expenses and economic conditions, among others.

Investable Universe of Companies Risk: The investable universe of companies in which the Fund may invest may be limited. If a company no longer meets the Index Provider’s criteria for inclusion in the Underlying Index, the Fund may need to reduce or eliminate its holdings in that company. The reduction or elimination of the Fund’s holdings in the company may have an adverse impact on the liquidity of the Fund’s overall portfolio holdings and on Fund performance.

Issuer Risk: Fund performance depends on the performance of individual companies in which the Fund invests. Changes to the financial condition of any of those companies may cause the value of their securities to decline.

Large-Capitalization Companies Risk: Large-capitalization companies may trail the returns of the overall stock market. Large-capitalization stocks tend to go through cycles of doing better - or worse - than the stock market in general. These periods have, in the past, lasted for as long as several years.

Liquidity Risk: Certain securities of MLPs may trade less frequently than those of larger companies due to their smaller capitalizations.

Listing Standards Risk: Under new continuous listing standards adopted by the Fund’s listing exchange, the Fund will be required to confirm on an ongoing basis that the components of the Underlying Index satisfy the applicable listing requirements. In the event that the Underlying Index does not comply with the applicable listing requirements, the Fund would be required to rectify such non-compliance by requesting that the Index Provider modify the Underlying Index, adopting a new underlying index, or obtaining relief from the SEC. Failure to rectify such non-compliance may result in the Fund being delisted by the listing exchange.

Management Risk: The Fund is subject to the risk that the Adviser’s investment management strategy may cause the Fund to underperform the market or its relevant benchmark or adversely affect the ability of the Fund to achieve its investment objective.

Market Risk: Turbulence in the financial markets and reduced liquidity may negatively affect issuers, which could have an adverse effect on the Fund. In addition, there is a risk that policy changes by the U.S. Government, Federal Reserve, or other government actors, which could include increasing interest rates, could cause increased volatility in financial markets and lead to higher levels of Fund redemptions, which could have a negative impact on the Fund. The Fund’s NAV could decline over short periods due to short-term market movements and over longer periods during market downturns.

Market Trading Risk: Shares of the Fund are publicly traded on a national securities exchange, which may subject shareholders to numerous market trading risks, including the potential lack of an active market for Shares, losses from trading in secondary markets, periods of high volatility and disruption in the creation/redemption process of the Fund. Any of these factors may lead to the Shares trading at a premium or discount to NAV.

Mid-Capitalization Companies Risk: Mid-capitalization companies may have greater price volatility, lower trading volume and less liquidity than large-capitalization companies. In addition, mid-capitalization companies may have smaller revenues, narrower product lines, less management depth and experience, smaller shares of their product or service markets, fewer financial resources and less competitive strength than large-capitalization companies.

MLP Risk: Investments in securities of an MLP involve risks that differ from investments in common stock, including risks related to limited control and limited rights to vote on matters affecting the MLP, risks related to potential conflicts of interest between the MLP and the MLP’s general partner, and cash flow risks. MLP common units and other equity securities can be affected by macro-economic and other factors affecting the stock market in general, expectations of interest rates, investor sentiment towards MLPs or the energy sector, changes in a particular issuer’s financial condition, or unfavorable or unanticipated poor performance of a particular issuer (in the case of MLPs, generally measured in terms of distributable cash flow). Prices of common units of individual MLPs and other equity securities also can be affected by fundamentals unique to the partnership or company, including earnings power and coverage ratios.

Non-Diversification Risk: The Fund is classified as a “non-diversified” investment company under the Investment Company Act of 1940 ("1940 Act"). As a result, the Fund is subject to the risk that it may be more volatile than a diversified fund because the Fund may invest its assets in a smaller number of issuers or may invest a larger proportion of its assets in a single issuer. As a result, the gains and losses on a single investment may have a greater impact on the Fund’s NAV and may make the Fund more volatile than more diversified funds.

Operational Risk: The Fund is exposed to operational risk arising from a number of factors, including but not limited to human error, processing and communication errors, errors of the Fund's service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund and the Adviser seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate for those risks that they are intended to address.

Passive Investment Risk: The Fund is not actively managed and the Adviser does not attempt to take defensive positions in declining markets. Unlike many investment companies, the Fund does not seek to outperform its Underlying Index. Therefore, it would not necessarily buy or sell a security unless that security is added or removed, respectively, from the Underlying Index, even if that security generally is underperforming. Maintaining investments in securities regardless of market conditions or the performance of individual securities could cause the Fund’s return to be lower than if the Fund employed an active strategy.

Potential Substantial After-Tax Tracking Error From Index Performance Risk: The Fund will be subject to taxation on its taxable income. The NAV of Shares will also be reduced by the accrual of any deferred tax liabilities. The Underlying Index, however, is calculated without any deductions for taxes. As a result, the Fund’s performance could differ significantly from the Underlying Index even if the pretax performance of the Fund and the performance of the Underlying Index are closely correlated. The performance of the Fund may diverge from that of the Underlying Index.

Premium/Discount Risk: Disruptions to creations and redemptions, the existence of extreme market volatility or potential lack of an active trading market for Shares may result in Shares trading at a significant premium or discount to NAV. If a shareholder purchases Shares at a time when the market price is at a premium to the NAV or sells Shares at a time when the market price is at a discount to the NAV, the shareholder may sustain losses.

Risks Related to Investing in the Energy Sector: The value of securities issued by companies in the energy sector may decline for many reasons, including, without limitation, changes in energy prices; international politics; energy conservation; the success of exploration projects; natural disasters or other catastrophes; changes in exchange rates, interest rates, or economic conditions; changes in demand for energy products and services; and tax and other government regulatory policies.

Risks Related to Investing in the Energy Infrastructure Industry Sector: The Fund invests primarily in energy infrastructure companies. Energy infrastructure companies are subject to risks specific to the industry they serve, including, but not limited to, the following:

• reduced volumes of natural gas or other energy commodities available for transporting, processing or storing;

• new construction and acquisition risk, which can limit growth potential;

• a sustained reduced demand for crude oil, natural gas and refined petroleum products resulting from a recession or an increase in market price or higher taxes;

• changes in the regulatory environment;

• extreme weather;

• rising interest rates, which could result in a higher cost of capital and drive investors into other investment opportunities; and

• threats of attack by terrorists.

Tax Risks: Tax risks associated with investments in the Fund include, but are not limited to, the following:

Deferred Tax Liability. Cash distributions from an MLP to the Fund that exceed the Fund’s allocable share of such MLP’s net taxable income are considered a tax-deferred return of capital that will reduce the Fund’s adjusted tax basis in the equity securities of the MLP. These reductions in the Fund’s adjusted tax basis in the MLP equity securities will increase the amount of gain (or decrease the amount of loss) recognized by the Fund on a subsequent sale of the securities. The Fund will accrue deferred income taxes for any future tax liability associated with (i) that portion of MLP distributions considered to be a tax-deferred return of capital as well as (ii) capital appreciation of its investments. Upon the sale of an MLP security, the Fund may be liable for previously deferred taxes. The Fund’s accrued deferred tax liability will be reflected each day in the Fund’s NAV. Increases in deferred tax liability will decrease the Fund's NAV. Conversely, decreases in deferred tax liability will increase the Fund's NAV. The Fund will rely to some extent on information provided by the MLPs in which it invests, which is not necessarily timely, to estimate deferred tax liability for purposes of financial statement reporting and determining the Fund's NAV. From time to time, the Adviser will modify the estimates or assumptions regarding the Fund’s deferred tax liability as new information becomes available. The Fund’s estimates regarding its deferred tax liability are made in good faith. However, the daily estimate of the Fund’s deferred tax liability used to calculate the Fund’s NAV could vary significantly from the Fund’s actual tax liability. The Fund will generally compute deferred income taxes based on the federal income tax rate applicable to corporations (currently 21%) and an assumed rate attributable to state taxes. To the extent that the distributions paid to you constitute a return of capital, the Fund's assets will decline. A decline in the Fund's assets may also result in an increase in the portion of a Fund's expense ratio that is not subject to a unitary fee or any other form of contractual cap, and over time the distributions paid in excess of net distributions received could work to erode the Fund's net asset value.

MLP Tax Risk. MLPs do not pay U.S. federal income tax at the partnership level. Rather, each partner is allocated a share of the partnership’s income, gains, losses, deductions and expenses. A change in current tax law, or a change in the underlying business mix of a given MLP, could result in an MLP being treated as a corporation for U.S. federal income tax purposes, which would result in such MLP being required to pay U.S. federal income tax on its taxable income. The classification of an MLP as a corporation for U.S. federal income tax purposes would have the effect of reducing the amount of cash available for distribution by the MLP. Thus, if any of the MLPs owned by the Fund were treated as corporations for U.S. federal income tax purposes, it could result in a reduction in the value of your investment in the Fund and lower income.

Return of Capital Distributions From the Fund Reduce the Tax Basis of Fund Shares. A portion of the Fund’s distributions are expected to be treated as a return of capital for tax purposes. Return of capital distributions are not taxable income to you, but reduce your tax basis in your Fund Shares. Such a reduction in tax basis will result in larger taxable gains and/or lower tax losses on a subsequent sale of Fund Shares. Shareholders who sell their Shares for less than they bought them may still recognize a gain due to the reduction in tax basis. Shareholders who periodically receive the payment of dividends or other distributions consisting of a return of capital may be under the impression that they are receiving net profits from the Fund when, in fact, they are not. Shareholders should not assume that the source of the distributions is from the net profits of the Fund. To the extent that the distributions paid to you constitute a return of capital, the Fund's assets will decline. A decline in the Fund's assets may also result in an increase in the portion of a Fund's expense ratio that is not subject to a unitary fee or any other form of contractual cap, and over time the distributions paid in excess of net distributions received could work to erode the Fund's net asset value.

Tax Status of the Fund. The Fund is taxed as a regular corporation ("C" corporation) for federal income tax purposes. This differs from most investment companies, which elect to be treated as regulated investment companies under the Code in order to avoid paying entity level income taxes. Under current law, the Fund is not eligible to elect treatment as a regulated investment company due to its investments primarily in MLPs invested in energy assets. As a result, the Fund will be obligated to pay applicable federal and state corporate income taxes on its taxable income as opposed to most investment companies which are not so obligated. The Fund expects that a portion of the distributions it receives from MLPs may be treated as a tax-deferred return of capital, thus reducing the Fund’s current tax liability. However, the amount of taxes currently paid by the Fund will vary depending on the amount of income and gains derived from investments and/or sales of MLP interests and such taxes may reduce your return from an investment in the Fund.

Tracking Error Risk: Tracking error is the divergence of the Fund's performance from that of the Underlying Index. Tracking error may occur because of differences between the securities and other instruments held in the Fund's portfolio and those included in the Underlying Index, pricing differences (including differences between a security's price at the local market close and the Fund's valuation of a security at the time of calculation of the Fund's NAV), differences in transaction costs, the Fund's holding of uninvested cash, differences in timing of the accrual of or the valuation of dividends or interest, tax gains or losses, changes to the Underlying Index or the costs to the Fund of complying with various new or existing regulatory requirements. This risk may be heightened during times of increased market volatility or other unusual market conditions. Tracking error also may result because the Fund incurs fees and expenses, while the Underlying Index does not. ETFs that track indices with significant weight in emerging markets issuers may experience higher tracking error than other index ETFs that do not track such indices.

Trading Halt Risk: An exchange or market may close or issue trading halts on specific securities, or the ability to buy or sell certain securities or financial instruments may be restricted, which may result in the Fund being unable to buy or sell certain securities or financial instruments. In such circumstances, the Fund may be unable to rebalance its portfolio, may be unable to accurately price its investments and/or may incur substantial trading losses.

U.S. Economic Risk: Decreasing U.S. imports, new trade regulations, changes in the U.S. dollar exchange rates, a recession in the United States or increases in foreclosures rates may have an adverse impact on the Fund.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is classified as a “non-diversified” investment company under the Investment Company Act of 1940 ("1940 Act"). As a result, the Fund is subject to the risk that it may be more volatile than a diversified fund because the Fund may invest its assets in a smaller number of issuers or may invest a larger proportion of its assets in a single issuer. As a result, the gains and losses on a single investment may have a greater impact on the Fund’s NAV and may make the Fund more volatile than more diversified funds.

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table that follow show how the Fund performed on a calendar year basis and provide an indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing the Fund's average annual total returns for the indicated periods compared with the Fund's benchmark index and a broad measure of market performance. On or around March 30, 2015, there was a change in the Fund's Underlying Index from Solactive MLP Composite Index to Solactive MLP Infrastructure Index.The Fund’s past performance (before and after taxes) is not necessarily indicative of how the Fund will perform in the future. Updated performance information is available online at www.globalxfunds.com.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.globalxfunds.com

Bar Chart [Heading]

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Annual Total Returns (Years Ended December 31)

Performance Table Heading

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Average Annual Total Returns (for the Periods Ended December 31, 2017)

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns are not relevant to investors who hold Shares of the Fund through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(Index returns reflects invested dividends net of withholding taxes, but reflects no deduction for fees, expenses, or other taxes)

1 Year

rr_AverageAnnualReturnYear01

(10.45%)

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

0.40%

^[1]

Prospectus:

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Label

rr_AverageAnnualReturnLabel

S&P 500 Index

5 Years

rr_AverageAnnualReturnYear05

15.80%

Trading Symbol

dei_TradingSymbol

MLPA

Distribution and Service (12b-1) Fees

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none

Expenses (as a percentage of Assets)

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0.46%

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

148

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 579

Annual Return 2014

rr_AnnualReturn2014

4.15%

Annual Return 2016

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21.12%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

21.41%

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Label

rr_AverageAnnualReturnLabel

Return before taxes

5 Years

rr_AverageAnnualReturnYear05

(1.02%)

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 18, 2012

Prospectus:

rr_ProspectusTable

1 Year

rr_AverageAnnualReturnYear01

(8.54%)

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

(1.38%)

^[3]

Prospectus:

rr_ProspectusTable

1 Year

rr_AverageAnnualReturnYear01

(8.32%)

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

(2.47%)

^[3]

Prospectus:

rr_ProspectusTable

Objective [Heading]

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INVESTMENT OBJECTIVE

Expense [Heading]

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FEES AND EXPENSES

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. The Fund had not yet commenced investment operations as of the most recent fiscal year end. Thus, no portfolio turnover rate is provided for the Fund.

Expense Example [Heading]

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Example:

Expense Example by, Year, Caption [Text]

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The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your Shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests at least 80% of its net assets in the securities of the Underlying Index. Moreover, at least 80% of the Fund’s net assets will be invested in securities that have economic characteristics of the Master Limited Partnership (“MLP”) natural gas asset class. The Fund’s 80% investment policies are non-fundamental and require 60 days prior written notice to shareholders before they can be changed.

The Index is intended to give investors a means of tracking the performance of the United States MLP natural gas asset class in the United States. As of January 31, 2018, the Underlying Index was comprised of 25 MLPs engaged in the transportation, storage, processing, marketing, exploration and production of natural gas. The Fund’s investment objective and Underlying Index may be changed without shareholder approval.

The Underlying Index is sponsored by Solactive AG, the provider of the Underlying Index ("Index Provider"), which is independent of the Fund and Global X Management Company LLC, the investment adviser for the Fund (“Adviser”). The Index Provider determines the relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index.

The Adviser uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to outperform the Underlying Index and does not seek temporary defensive positions when markets decline or appear overvalued.

The Fund uses a replication strategy. A replication strategy is an indexing strategy that involves investing in the securities of the Underlying Index in approximately the same proportions as in the Underlying Index. However, the Fund may utilize a representative sampling strategy with respect to the Underlying Index when a replication strategy might be detrimental or disadvantageous to shareholders, such as when there are practical difficulties or substantial costs involved in compiling a portfolio of equity securities to replicate the Underlying Index, in instances in which a security in the Underlying Index becomes temporarily illiquid, unavailable or less liquid, or as a result of legal restrictions or limitations that apply to the Fund but not the Underlying Index.

MLPs are publicly traded partnerships engaged in the transportation, storage, processing, refining, marketing, exploration, production, and mining of natural resources. By confining their operations to these specific activities, their interests, or units, are able to trade on public securities exchanges exactly like the shares of a corporation, without entity-level taxation.

To qualify as a MLP and not to be taxed as a corporation, a partnership must receive at least 90% of its income from qualifying sources as set forth in Section 7704(d) of the Internal Revenue Code of 1986, as amended (the “Code”). These qualifying sources include interest, dividends, real estate rents, gain from the sale or disposition of real property, income and gain from mineral or natural resources activities, income and gain from the transportation or storage of certain fuels, gain from the sale or disposition of a capital asset held for the production of income described in the foregoing, and, in certain circumstances, income and gain from commodities or futures, forwards and options with respect to commodities.

MLPs generally have two classes of owners, the general partner and limited partners. The general partner of an MLP is typically owned by a major energy company, an investment fund, or the direct management of the MLP, or is an entity owned by one or more of such parties. The general partner may be structured as a private or publicly traded corporation or other entity. The general partner typically controls the operations and management of the MLP through an up to 2% equity interest in the MLP plus, in many cases, ownership of common units and subordinated units. Limited partners typically own the remainder of the partnership, through ownership of common units, and have a limited role in the partnership’s operations and management. MLPs are typically structured such that common units and general partner interests have first priority to receive quarterly cash distributions up to an established minimum amount (“minimum quarterly distributions” or “MQD”). Common and general partner interests also accrue arrearages in distributions to the extent the MQD is not paid. Once common and general partner interests have been paid, subordinated units receive distributions of up to the MQD; however, subordinated units do not accrue arrearages. Distributable cash in excess of the MQD is paid to both common and subordinated units and is distributed to both common and subordinated units generally on a pro rata basis. The general partner is also eligible to receive incentive distributions if the general partner operates the business in a manner which results in distributions paid per common unit surpassing specified target levels. As the general partner increases cash distributions to the limited partners, the general partner receives an increasingly higher percentage of the incremental cash distributions.

Due to the nature of the Fund’s investments, the Fund will not qualify as a regulated investment company under the Code. As a result, the Fund will be taxed as a regular corporation ("C" corporation) for federal income tax purposes.

The Adviser seeks a correlation over time of 95% or better between the Fund’s performance, before fund fees, expenses, and taxes, and the performance of the Underlying Index. A correlation percentage of 100% would indicate perfect correlation. If the Fund uses a replication strategy, it can be expected to have greater correlation to the Underlying Index than if it uses a representative sampling strategy.

The Fund concentrates its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. As of January 31, 2018, the Fund was concentrated in the energy sector.

Risk [Heading]

rr_RiskHeading

SUMMARY OF PRINCIPAL RISKS

Risk Lose Money [Text]

rr_RiskLoseMoney

As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

PERFORMANCE INFORMATION

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

The Fund has not commenced operations as of the date of this prospectus. Thus, no bar chart or average annual total returns table is included for the Fund.

Prospectus:

rr_ProspectusTable

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.58%

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

$ 186

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. For the most recent fiscal period, the Fund’s portfolio turnover rate was 40.42% of the average value of its portfolio.

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You will also incur usual and customary brokerage commission when buying and selling Shares.

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. This example does not take into account customary brokerage commissions that you pay when purchasing or selling Shares of the Fund in the secondary market.

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGIES

Strategy Portfolio Concentration [Text]

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The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. As of January 31, 2018, the Fund was concentrated in the energy sector.

Risk Narrative [Text Block]

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As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments. There is no guarantee that the Fund will achieve its investment objective. The Fund is subject to the principal risks noted below, any of which may adversely affect the Fund's net asset value ("NAV"), trading price, yield, total return and ability to meet its investment objective, as well as other risks that are described in greater detail in the Additional Information About the Funds section of this Prospectus and in the Statement of Additional Information ("SAI").

Asset Class Risk: Securities in the Underlying Index or otherwise held in the Fund's portfolio may underperform in comparison to the general securities markets or other asset classes.

Asset Fluctuation Risk: Certain shareholders, including an Authorized Participant (as defined in the SAI), the Adviser or an affiliate of the Adviser, may own a substantial amount of the Fund’s Shares. Additionally, from time to time an Authorized Participant, a third party investor, the Adviser, or an affiliate of the Adviser may invest in the Fund and hold its investment for a specific period of time in order to facilitate commencement of the Fund’s operations or to allow the Fund to achieve size or scale. Redemptions by large shareholders could have a significant negative impact on the Fund. If a large shareholder were to redeem all, or a large portion, of its Shares, there is no guarantee that the Fund will be able to maintain sufficient assets to continue operations, in which case the Board of Trustees may determine to liquidate the Fund. In addition, transactions by large shareholders may account for a large percentage of the trading volume on a national securities exchange and may, therefore, have a material upward or downward effect on the market price of the Shares.

Authorized Participant Concentration Risk: The Fund has a limited number of financial institutions that may act as Authorized Participants. Only Authorized Participants who have entered into agreements with the Fund’s distributor may engage in creation or redemption transactions directly with the Fund. To the extent that those Authorized Participants exit the business or are unable to process creation and/or redemption orders, and no other Authorized Participant is able to step forward to create or redeem in either of those cases, Shares may be more likely to trade at a premium or discount to NAV, and possibly face trading halts and/or delisting from a securities exchange. The Authorized Participant Concentration Risk may be heightened because the Fund invests in non-U.S. securities.

Commodities Exposure Risk: To the extent that its Underlying Index invests in, or otherwise has exposure to, securities and markets that are susceptible to fluctuations in certain commodity markets, any negative changes in commodity markets could have a great impact on the Fund. Commodity prices may be influenced or characterized by unpredictable factors, including, where applicable, high volatility, changes in supply and demand relationships, weather, agriculture, trade, changes in interest rates and monetary and other governmental policies, action and inaction. Securities of companies held by the Fund that are dependent on a single commodity, or are concentrated on a single commodity sector, may typically exhibit even higher volatility attributable to commodity prices.

Concentration Risk: Because the Fund's investments are concentrated in the energy sector, the Fund will be susceptible to loss due to adverse occurrences affecting this sector or industry. To the extent that the Underlying Index concentrates in the securities of issuers in a particular country, industry, market, asset class, or sector, the Fund will also concentrate its investments to approximately the same extent. By concentrating its investments in a country, industry, market, asset class, or sector, the Fund faces more risks than if it were diversified broadly over numerous countries, industries, markets, asset classes, or sectors. Such risks, any of which may adversely affect the companies in which the Fund invests, may include, but are not limited to, the following: general economic conditions or cyclical market patterns that could negatively affect supply and demand; competition for resources; adverse labor relations; political or world events; obsolescence of technologies; and increased competition or new product introductions that may affect the profitability or viability of companies in a sector or industry. In addition, at times, such country, industry, market, asset class, or sector may be out of favor and underperform other sectors or industries or the market as a whole. For additional details on these risks, please see Risks Related to Investing in the Energy Sector.

Cyber Security Risk: Failures or breaches of the electronic systems of the Fund, the Adviser, and the Fund's other service providers, market makers, Authorized Participants or the issuers of securities in which the Fund invests have the ability to cause disruptions and negatively impact the Fund's business operations, potentially resulting in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cyber security plans and systems of the Fund's service providers, market makers, Authorized Participants or issuers of securities in which the Fund invests.

Equity Securities Risk: Equity securities are subject to changes in value and their values may be more volatile than other asset classes, as a result of such factors as a company’s business performance, investor perceptions, stock market trends and general economic conditions.

Foreign Securities Risk: The Fund's investments in foreign securities can be riskier than U.S. securities investments. Investments in the securities of foreign issuers (including investments in ADRs and GDRs) are subject to the risks associated with investing in those foreign markets, such as heightened risks of inflation or nationalization. The prices of foreign securities and the prices of U.S. securities have, at times, moved in opposite directions. In addition, securities of foreign issuers may lose value due to political, economic and geographic events affecting a foreign issuer or market. During periods of social, political or economic instability in a country or region, the value of a foreign security traded on U.S. exchanges could be affected by, among other things, increasing price volatility, illiquidity, or the closure of the primary market on which the security (or the security underlying the ADR or GDR) is traded. You may lose money due to political, economic and geographic events affecting a foreign issuer or market.

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

Industry Specific Risk: MLPs operating in the energy sector are also subject to risks specific to the industry they serve.

Midstream. Midstream MLPs that provide crude oil, refined product and natural gas services are subject to supply and demand fluctuations in the markets they serve, which may be impacted by a wide range of factors, including fluctuating commodity prices, weather, increased conservation or use of alternative fuel sources, increased governmental or environmental regulation, depletion, rising interest rates, declines in domestic or foreign production, accidents or catastrophic events, increasing operating expenses and economic conditions, among others.

Marine shipping. Marine shipping MLPs are primarily marine transporters of natural gas, crude oil or refined petroleum products. Marine shipping companies are exposed to many of the same risks as other energy companies. The highly cyclical nature of the marine transportation industry may lead to volatile changes in charter rates and vessel values, which may adversely affect the revenues, profitability and cash flows of MLPs with marine transportation assets.

International Closed Market Trading Risk: To the extent that the underlying securities held by the Fund trade on foreign exchanges that may be closed when the securities exchange on which the Fund’s Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund’s quote from the closed foreign market). These deviations could result in premiums or discounts to the Fund’s NAV that may be greater than those experienced by other exchange-traded funds ("ETFs").