The table below describes the fees and expenses that you pay if you buy and hold shares of the Fund (“Shares”). Investors may pay brokerage commissions on their purchases and sales of Shares.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

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)

Fee Waiver or Reimbursement over Assets, Date of Termination

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2015-09-30

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it purchases and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may result in higher transaction costs and 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, may affect the Fund’s performance. This Fund is newly offered. Therefore, it does not have a turnover rate to report for the most recent fiscal year.

Expense Exchange Traded Fund Commissions [Text]

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This example does not take into account brokerage commissions that you pay when purchasing or selling Shares.

Other Expenses, New Fund, Based on Estimates [Text]

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“Other Expenses” are based on estimated amounts for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This 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 brokerage commissions that you pay when purchasing or selling Shares.

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

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund is an actively-managed exchange-traded fund (“ETF”) that will invest under normal circumstances primarily (at least 65% of its assets) in domestic and foreign equity securities of companies that are relevant to the Fund’s investment theme of disruptive innovation. Companies relevant to this theme are those that rely on or benefit from the development of new products or services, technological improvements and advancements in scientific research relating to the areas of genomics (“Genomic Revolution Companies”), industrial innovation (“Industrial Innovation Companies”) or the increased use of shared technology, infrastructure and services (“Web x.0 Companies”).

In selecting companies that the Adviser believes are relevant to a particular investment theme, it seeks to identify, using its own internal research and analysis, companies capitalizing on disruptive innovation or that are enabling the further development of a theme in the markets in which they operate. The Adviser’s internal research and analysis leverages insights from diverse sources, including external research, to develop and refine its investment themes and identify and take advantage of trends that have ramifications for individual companies or entire industries. The types of companies that the Adviser believes are Genomic Revolution Companies, Industrial Innovation Companies or Web x.0 Companies are described below.

Genomic Revolution Companies. Companies that the Adviser believes are substantially focused on and are expected to substantially benefit from extending and enhancing the quality of human and other life by incorporating technological and scientific developments, improvements and advancements in genomics into their business, such as by offering new products or services that rely on genomic sequencing, analysis, synthesis or instrumentation. These companies may include ones across multiple sectors, such as healthcare, information technology, materials, energy and consumer discretionary, that develop, produce, manufacture or significantly rely on or enable bionic devices, bio-inspired computing, bioinformatics, molecular medicine and agricultural biotechnology.

Industrial Innovation Companies: Companies that are focused on and expected to benefit from the development of new products or services, technological improvements and advancements in scientific research related to, among other things, disruptive innovation in energy (“energy transformation companies”), automation and manufacturing (“automation transformation companies” ) , materials, and transportation.

The Adviser considers a company to be an energy transformation company if it seeks to capitalize on innovations or evolutions in: (i) ways that energy is stored or used; (ii) the discovery, collection and/or implementation of new sources of energy, including unconventional sources of oil or natural gas and/or (iii) the production or development of new materials for use in commercial applications of energy production, use or storage.

The Adviser considers a company to be an automation transformation company if it is focused on man capitalizing on the productivity of machines, such as through the automation of functions, processes or activities previously performed by human labor or the use of robotics to perform other functions, activities or processes.

Web x.0 Companies. Companies that are focused on and expected to benefit from shifting the bases of technology infrastructure from hardware and software to the cloud, enabling mobile and local services, such as companies that rely on or benefit from the increased use of shared technology, infrastructure and services. These companies may also include ones that develop, use or rely on innovative payment methodologies, big data, the internet of things, and social distribution and media.

The Adviser will select investments for the Fund that represent its highest-conviction investment ideas within the theme of disruptive innovation, as described above, in constructing the Fund’s portfolio. The Adviser’s process for identifying genomic companies, industrial innovation companies and Web x.0 companies uses both “top down” (macro-economic and business cycle analysis) and “bottom up” (valuation, fundamental and quantitative measures) approaches. The Adviser’s highest-conviction investment ideas are those that it believes present the best risk-reward opportunities.

Under normal circumstances, substantially all of the Fund’s assets will be invested in equity securities, including common stocks, partnership interests, business trust shares and other equity investments or ownership interests in business enterprises. The Fund’s investments will include issuers of micro-, small-, medium- and large-capitalizations. The Fund’s investments in foreign equity securities will be in both developed and emerging markets. The Fund currently intends to use only American Depositary Receipts (“ADRs”) when purchasing foreign securities.

The Fund will not be concentrated in any industry.

Strategy Portfolio Concentration [Text]

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The Fund will not be concentrated in any industry

Risk [Heading]

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Principal Risks

Risk Narrative [Text Block]

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There is no assurance that the Fund will meet its investment objective. The value of your investment in the Fund, as well as the amount of return you receive on your investment in the Fund, may fluctuate significantly. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. Therefore, you should consider carefully the following risks before investing in the Fund.

Emerging Market Securities Risk . Investment in securities of emerging market companies may present risks that are greater than or different from those associated with foreign securities due to less developed and liquid markets and such factors as increased economic, political, regulatory, or other uncertainties.

Equity Securities Risk. The value of the equity securities the Fund holds may fall due to general market and economic conditions, perceptions regarding the industries in which the issuers of securities the Fund holds participate or factors relating to specific companies in which the Fund invests. An unfavorable earnings report or a failure to make anticipated dividend payments by an issuer held by the Fund may affect the value of the Fund’s investment. Equity securities may also be particularly sensitive to general movements in the stock market, and a decline in the broader market may affect the value of the Fund’s equity investments.

Foreign Securities Risk. Investments in the securities of foreign issuers involve risks beyond those associated with investments in U.S. securities. These additional risks include greater market volatility, the availability of less reliable financial information, higher transactional costs, potentially higher custody costs, taxation by foreign governments, decreased market liquidity and political and economic instability. Because the Fund investments in foreign securities currently are made through the purchase of ADRs, the Fund normally will not be hedging any foreign currency exposure (since ADRs are denominated and pay dividends in US dollars).

Health Care Sector Risk . The health care sector may be affected by government regulations and government health care programs, restrictions on government reimbursement for medical expenses, increases or decreases in the cost of medical products and services and product liability claims, among other factors. Many health care companies are (i) heavily dependent on patent protection and intellectual property rights and the expiration of a patent may adversely affect their profitability, (ii) subject to extensive litigation based on product liability and similar claims, and (iii) subject to competitive forces that may make it difficult to raise prices and, in fact, may result in price discounting. Many health care products and services may be subject to regulatory approvals. The process of obtaining such approvals may be long and costly, and delays or failure to receive such approvals may negatively impact the business of such companies. Additional or more stringent laws and regulations enacted in the future could have a material adverse effect on such companies in the health care sector. In addition, issuers in the health care sector include issuers having their principal activities in the biotechnology industry, medical laboratories and research, drug laboratories and research and drug manufacturers, which have the additional risks described below.

Biotechnology Company Risk. A biotechnology company’s valuation can often be based largely on the potential or actual performance of a limited number of products and can accordingly be greatly affected if one of its products proves unsafe, ineffective or unprofitable. Biotechnology companies are subject to regulation by, and the restrictions of, the Food and Drug Administration, the Environmental Protection Agency, state and local governments, and foreign regulatory authorities.

Pharmaceutical Company Risk. Companies in the pharmaceutical industry can be significantly affected by government approval of products and services, government regulation and reimbursement rates, product liability claims, patent expirations and protection and intense competition.

Industrials Sector Risk. The industrials sector includes companies engaged in the aerospace and defense industry, electrical engineering, machinery, and professional services. Companies in the industrials sector may be adversely affected by changes in government regulation, world events and economic conditions. In addition, companies in the industrials sector may be adversely affected by environmental damages, product liability claims and exchange rates.

Aerospace and Defense Company Risk. Companies in the aerospace and defense industry rely to a large extent on U.S. (and other) Government demand for their products and services and may be significantly affected by changes in government regulations and spending, as well as economic conditions and industry consolidation.

Professional Services Company Risk. Professional services companies may be materially impacted by economic conditions and related fluctuations in client demand for marketing, business, technology and other consulting services. Professional services companies’ success depends in large part upon attracting and retaining key employees and a failure to do so could adversely affect a company’s business. There are relatively few barriers to entry into the professional services market, and new competitors could readily seek to compete in one or more market segments, which could adversely affect company’s operating results through pricing pressure and loss of market share.

Information Technology Sector Risk. The information technology sector includes companies engaged in internet software and services, technology hardware and storage peripherals, electronic equipment instruments and components, and semiconductors and semiconductor equipment. Information technology companies face intense competition, both domestically and internationally, which may have an adverse affect on profit margins. Information technology companies may have limited product lines, markets, financial resources or personnel. The products of information technology companies may face product rapid obsolescence due to technological developments and frequent new product introduction, unpredictable changes in growth rates and competition for the services of qualified personnel. Failure to introduce new products, develop and maintain a loyal customer base or achieve general market acceptance for their products could have a material adverse effect on a company’s business. Companies in the information technology sector are heavily dependent on intellectual property and the loss of patent, copyright and trademark protections may adversely affect the profitability of these companies.

Internet Company Risk. Many Internet-related companies have incurred large losses since their inception and may continue to incur large losses in the hope of capturing market share and generating future revenues. Accordingly, many such companies expect to incur significant operating losses for the foreseeable future, and may never be profitable. The markets in which many Internet companies compete face rapidly evolving industry standards, frequent new service and product announcements, introductions and enhancements and changing customer demands. The failure of an Internet company to adapt to such changes could have a material adverse effect on the company’s business. In addition, the widespread adoption of new Internet, networking, telecommunications technologies, or other technological changes could require substantial expenditures by an Internet company to modify or adapt its services or infrastructure, which could have a material adverse effect on an Internet company’s business.

Semiconductor Company Risk. Competitive pressures may have a significant effect on the financial condition of semi-conductor companies and, as product cycles shorten and manufacturing capacity increases, these companies may become increasingly subject to aggressive pricing, which hampers profitability. Reduced demand for end-user products, under-utilization of manufacturing capacity, and other factors could adversely impact the operating results of companies in the semiconductor sector. Semiconductor companies typically face high capital costs and may be heavily dependent on intellectual property rights. The semiconductor sector is highly cyclical, which may cause the operating results of many semiconductor companies to vary significantly. The stock prices of companies in the semiconductor sector have been and likely will continue to be extremely volatile.

Issuer Risk. Because a Fund may invest in approximately 40 to 50 issuers, it is subject to the risk that the value of the Fund’s portfolio may decline due to a decline in value of the equity securities of particular issuers. The value of an issuer’s equity securities may decline for reasons directly related to the issuer, such as management performance and reduced demand for the issuer’s goods or services.

Large-Capitalization Companies Risk. Large-capitalization companies tend to be less volatile than companies with smaller market capitalizations. In exchange for this potentially lower risk, the value of a large-capitalization company may not rise as much as that of a company with a smaller market capitalization.

Management Risk. As an actively-managed ETF, the Fund is subject to management risk. Although the portfolio manager has significant investment management experience, the Adviser is newly-formed and has no prior experience managing actively-managed ETFs. The ability of the Adviser to successfully implement the Fund’s investment strategies will significantly influence the Fund’s performance.

Market Trading Risk. The Fund faces numerous market trading risks, including disruptions to the creation and redemption processes of the Fund, losses from trading in secondary markets, the existence of extreme market volatility or potential lack of an active trading market for Shares, which may result in Shares trading at a significant premium or discount to their net asset value (“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.

Market Risk . The value of the Fund’s assets will fluctuate as the markets in which the Fund invests fluctuate. The value of its investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market.

Micro-Capitalization Companies Risk. Micro-capitalization companies are subject to substantially greater risks of loss and price fluctuations because their earnings and revenues tend to be less predictable (and some companies may be experiencing significant losses). Their share prices tend to be more volatile and their markets less liquid than companies with larger market capitalizations. The shares of micro-capitalization companies tend to trade less frequently than those of larger, more established companies, which can adversely affect the pricing of these securities and the future ability to sell these securities.

New Fund Risk. There can be no assurance that the Fund will grow to or maintain an economically viable size. The Fund may liquidate and terminate at any time without shareholder approval.

Non-Diversified Risk. The Fund is classified as a “non-diversified” investment company under the 1940 Act. Therefore, the Fund may invest a relatively higher percentage of its assets in a relatively 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.

Small- and Medium-Capitalization Companies Risk . Small- and medium-capitalization companies may be more volatile and more likely than large-capitalization companies to have narrower product lines, fewer financial resources, less management depth and experience and less competitive strength. Returns on investments in securities of small- and medium-capitalization companies could trail the returns on investments in securities of large-capitalization companies.

Web x.0 Companies Risk. The risks described below apply, in particular, to the Fund’s investment in Web x.0 Companies.

Internet Information Provider Company Risk. Internet information provider companies provide Internet navigation services and reference guide information and publish, provide or present proprietary, advertising and/or third party content. Such companies often derive a large portion of their revenues from advertising, and a reduction in spending by or loss of advertisers could seriously harm their business. This business is rapidly evolving and intensely competitive, and is subject to changing technologies, shifting user needs, and frequent introductions of new products and services. The research and development of new, technologically advanced products is a complex and uncertain process requiring high levels of innovation and investment, as well as the accurate anticipation of technology, market trends and consumer needs. The number of people who access the Internet is increasing dramatically and a failure to attract and retain a substantial number of such users to a company’s products and services or to develop products and technologies that are more compatible with alternative devices could adversely affect operating results. Concerns regarding a company’s products, services or processes compromise the privacy of users or other privacy related matters, even if unfounded, could damage a company’s reputation and adversely affect operating results.

Catalog and Mail Order House Company Risk. Catalog and mail order house companies may be exposed to significant inventory risks that may adversely affect operating results due to seasonality, new product launches, rapid changes in product cycles and pricing, defective merchandise, changes in consumer demand and consumer spending patterns, changes in consumer tastes with respect to products, and other factors. Demand for products can change significantly between the time inventory or components are ordered and the date of sale. The acquisition of certain types of inventory or components may require significant lead-time and prepayment and they may not be returnable. Failure to adequately predict customer demand or otherwise optimize and operate distribution centers could result in excess or insufficient inventory or distribution capacity, result in increased costs, impairment charges, or both. The business of catalog and mail order house companies can be highly seasonal and failure to stock or restock popular products in sufficient amounts during high demand periods could significantly affect revenue and future growth. Increased website traffic during peak periods could cause system interruptions which may reduce the volume of goods sold and the attractiveness of a company’s products and services.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

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The Fund is classified as a “non-diversified” investment company under the 1940 Act. Therefore, the Fund may invest a relatively higher percentage of its assets in a relatively 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.

Bar Chart and Performance Table [Heading]

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Performance

Performance One Year or Less [Text]

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The Fund has not yet commenced operations and therefore does not have a performance history. Once available, the Fund’s performance information will be accessible on the Fund’s website at http://ark-invest.com.

Performance Availability Website Address [Text]

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http://ark-invest.com

Performance Narrative [Text Block]

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ARK Innovation ETF (Prospectus Summary) | ARK Innovation ETF | ARK Innovation ETF

Risk/Return:

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Shareholder Fees (fees paid directly from your investment)

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None

Management Fee

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0.95%

Distribution and/or Service (12b-1) Fees

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none

Other Expenses

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0.50%

^[1]

Total Annual Fund Operating Expenses

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1.45%

Expense Reduction

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0.50%

^[2]

Net Annual Fund Operating Expenses

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0.95%

Expense Example, with Redemption, 1 Year

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$ 97

Expense Example, with Redemption, 3 Years

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$ 409

[1]

The Fund bears other expenses that are not covered under the management fee, which may vary and affect the total level of expenses paid by the Fund, such as taxes and governmental fees, brokerage fees, commissions and other transaction expenses, certain custodial fees and expenses, costs of borrowing money, including interest expenses, and extraordinary expenses (such as litigation and indemnification expenses) (“Fund Expenses”). “Other Expenses” are based on estimated amounts for the current fiscal year.

[2]

ARK Investment Management LLC (“Adviser”) has contractually agreed, until September 30, 2015, to waive or limit its management fee or reimburse the Fund to the extent that various organizational and other expenses of the Fund (excluding Fund Expenses detailed in footnote (a) above) exceed 0.95% (“Expense Limit”) of the Fund’s average net assets. Under the Expense Limitation Agreement, which, after the initial term, renews annually for a full year unless terminated by the Adviser upon at least 30 days’ notice prior to the end of the contract term, the Adviser may recoup these waivers and reimbursements in future periods, not exceeding three years, provided organizational and other Fund expenses plus such recoupment, do not exceed the Expense Limit.