2.2.0.25truefalse010007 - Document - Risk/Return Summary (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) {Unlabeled}falsefalsetrue1falsefalseUSDtruefalse{dei_DocumentInformationDocumentAxis} : First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member] 2/1/2010 - 1/31/2011 USD ($) $TwelveMonthsEnded_31Jan2011_S000026919_Memberhttp://www.sec.gov/CIK0001364608duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberPureStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false0rr_RiskReturnHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00SUMMARY INFORMATION First Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicatedReference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 falsefalseRisk/Return [Heading]4false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00INVESTMENT OBJECTIVEfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective [Heading]5false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The First Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Fund (the "Fund") seeks investment results that correspond generally to the price and yield (before the Fund's fees and expenses) of an equity index called the NASDAQ OMX(R) Clean Edge(R) Smart Grid Infrastructure Index(SM) (the "Index").falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective, Primary [Text Block]6false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00FEES AND EXPENSES OF THE FUNDfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Fee Table Includes the following information, in plain English under rule 421(d) under the Securities Act, after Item 2 Fees and expenses of the Fund This table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Shareholder Fees (fees paid directly from your investment) Example This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be You would pay the following expenses if you did not redeem your shares The Example does not reflect sales charges (loads) on reinvested dividends [and other distributions]. If these sales charges (loads) were included, your costs would be higher. Portfolio Turnover The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was __% of the average value of its whole portfolio. Instructions. A.3.instructions.6 New Funds. For purposes of this Item, a "New Fund" is a Fund that does not include in Form N-1A financial statements reporting operating results or that includes financial statements for the Fund's initial fiscal year reporting operating results for a period of 6 months or less. The following Instructions apply to New Funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph d -Subsection instructions falsefalseExpense [Heading]7false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The following table describes the fees and expenses you may pay if you buy and hold Shares of the Fund. Investors purchasing and selling Shares may be subject to costs (including customary brokerage commissions) charged by their broker.falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThis table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown.The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Narrative [Text Block]8false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00SHAREHOLDER FEES (fees paid directly from your investment)falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringShareholder Fees (fees paid directly from your investment).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subsection table falsefalseShareholder Fees Caption [Text]9false0rr_ShareholderFeesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://ftportfolios.com/role/ShareholderFeesFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>falsefalse<div style="display:none">~ http://ftportfolios.com/role/ShareholderFeesFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>falsehttp://ftportfolios.com/role/ShareholderFeesFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFundfalsefalse0200108 - Schedule - Shareholder Fees (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund)truefalsefalse1falseColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxis*ColumnunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*4false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruetrue0.00000.0000falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureMaximum Deferred Sales Charge (Load) (as a percentage of ____) A.3.instructions.2.a.i "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection table falsefalseMaximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricetruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsetruefalseOthernanafalsefalseMaximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)11Shareholder Fees (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No authoritative reference available.falsefalseShareholder Fees [Table]10false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00ANNUAL FUND OPERATING EXPENSES (Expenses that you pay each year as a percentage of the value of your investment)falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 7 -Subsection table falsefalseOperating Expenses Caption [Text]11false0rr_AnnualFundOperatingExpensesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://ftportfolios.com/role/AnnualFundOperatingExpensesFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>falsefalse<div style="display:none">~ http://ftportfolios.com/role/AnnualFundOperatingExpensesFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>falsehttp://ftportfolios.com/role/AnnualFundOperatingExpensesFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFundfalsefalse0200208 - Schedule - Annual Fund Operating Expenses (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund)truefalsefalse1falseColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxis*ColumnunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*4false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruetrue0.00400.0040falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureManagement Fees include investment advisory fees (including any fees based on the Fund's performance), any other management fees payable to the investment adviser or its affiliates, and administrative fees payable to the investment adviser or its affiliates that are not included as "Other Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph a -Subsection instructions falsefalseManagement Fees0rr_ManagementFeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00400.0040falsefalsefalsetruefalseOthernanafalsefalseManagement Fees2falseRowprimaryElement*5false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruetrue0.00000.0000falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureDistribution [and/or Service] (12b-1) Fees" include all distribution or other expenses incurred during the most recent fiscal year under a plan adopted pursuant to rule 12b-1 [17 CFR 270.12b-1]. Under an appropriate caption or a subcaption of "Other Expenses," disclose the amount of any distribution or similar expenses deducted from the Fund's assets other than pursuant to a rule 12b-1 plan.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 9 -Subsection table falsefalseDistribution and Service (12b-1) Fees0rr_DistributionAndService12b1FeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsetruefalseOthernanafalsefalseDistribution and Service (12b-1) Fees3falseRowprimaryElement*6false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruetrue0.00590.0059falsefalsefalsetruefalseOtherrr:NonNegativePure4Typepure"Other Expenses" include all expenses not otherwise disclosed in the table that are deducted from the Fund's assets or charged to all shareholder accounts. The amount of expenses deducted from the Fund's assets are the amounts shown as expenses in the Fund's statement of operations (including increases resulting from complying with paragraph 2(g) of rule 6-07 of Regulation S-X [17 CFR 210.6-07]). "Other Expenses" do not include extraordinary expenses as determined under generally accepted accounting principles (see Accounting Principles Board Opinion No. 30). If extraordinary expenses were incurred that materially affected the Fund's "Other Expenses," disclose in a footnote to the table what "Other Expenses" would have been had the extraordinary expenses been included.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph c -Clause i -Subsection instructions truefalseOther Expenses0rr_OtherExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00590.0059falsefalsefalsetruefalseOthernanafalsefalseOther Expenses4falseRowprimaryElement*7false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruetrue0.00990.0099falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses. If the Fund is a Feeder Fund, reflect the aggregate expenses of the Feeder Fund and the Master Fund in a single fee table using the captions provided. In a footnote to the fee table, state that the table and Example reflect the expenses of both the Feeder and Master Funds. If the prospectus offers more than one Class of a Multiple Class Fund or more than one Feeder Fund that invests in the same Master Fund, provide a separate response for each Class or Feeder Fund. Base the percentages of "Annual Fund Operating Expenses" on amounts incurred during the Fund's most recent fiscal year, but include in expenses amounts that would have been incurred absent expense reimbursement or fee waiver arrangements. If the Fund has changed its fiscal year and, as a result, the most recent fiscal year is less than three months, use the fiscal year prior to the most recent fiscal year as the basis for determining "Annual Fund Operating Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph d -Subsection instructions falsefalseTotal Annual Fund Operating Expenses0rr_ExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00990.0099falsefalsefalsetruefalseOthernanafalsefalseTotal Annual Fund Operating Expenses5falseRowprimaryElement*8false0rr_FeeWaiverOrReimbursementOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegatedtotal1truetruetrue0.00290.0029[1]falsefalsefalsetruefalseOtherrr:NonPositivePure4TypepureTotal Annual Fund Operating Expenses. If there were expense reimbursement or fee waiver arrangements that reduced any Fund operating expenses and will continue to reduce them for no less than one year from the effective date of the Fund's registration statement, a Fund may add two captions to the table one caption showing the amount of the expense reimbursement or fee waiver, and a second caption showing the Fund's net expenses after subtracting the fee reimbursement or expense waiver from the total fund operating expenses. The Fund should place these additional captions directly below the "Total Annual Fund Operating Expenses" caption of the table and should use appropriate descriptive captions, such as "Fee Waiver [and/or Expense Reimbursement]" and "Total Annual Fund Operating Expenses After Fee Waiver [and/or Expense Reimbursement]," respectively. If the Fund provides this disclosure, also disclose the period for which the expense reimbursement or fee waiver arrangement is expected to continue, and briefly describe who can terminate the arrangement and under what circumstances.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table truefalseFee Waiver and Expense Reimbursement0rr_FeeWaiverOrReimbursementOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse[1]1truetruetrue0.00290.0029falsefalsefalsetruefalseOthernanafalsefalseFee Waiver and Expense Reimbursement6falseRowprimaryElement*9false0rr_NetExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruetrue0.00700.0070falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table falsefalseTotal Net Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement0rr_NetExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00700.0070falsefalsefalsetruefalseOthernanafalsefalseTotal Net Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement1First Trust has agreed to waive fees and/or pay the Fund's expenses to the extent necessary to prevent the operating expenses of the Fund (excluding interest expense, brokerage commissions and other trading expenses, taxes, and extraordinary expenses) from exceeding 0.60% of its average daily net assets per year at least until January 20, 2013. Expenses borne by First Trust are subject to reimbursement by the Fund or up to three years from the date the fee or expense was incurred, but no reimbursement payment will be made by the Fund at any time if it would result in the Fund's expenses exceeding 0.70% of its average daily net assets per year. The agreement may be terminated by the Trust on behalf of the Fund at any time and by First Trust only after January 20, 2013 upon 60 days' written notice.16Annual Fund Operating Expenses (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No authoritative reference available.falsefalseAnnual Fund Operating Expenses [Table]12false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00EXAMPLEfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalseExpense Example [Heading]13false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The example below 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.</p><p>The example assumes that you invest $10,000 in the Fund for the time periods indicated and then you retain the Shares or redeem 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 net operating expenses remain at current levels until January 20, 2013. Additionally, the example assumes that the Fund imposes a 12b-1 fee of 0.25% per annum of the Fund's average daily net assets following January 31, 2012. The example assumes that First Trust's agreement to waive fees and/or pay the Fund's expenses to the extent necessary to prevent the operating expenses of the Fund (excluding interest expense, brokerage commissions and other trading expenses, taxes, and extraordinary expenses) from exceeding 0.70% of average daily net assets per year will be terminated following January 20, 2013. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</p>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThe Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection example falsefalseExpense Example Narrative [Text Block]14false0rr_ExpenseExampleWithRedemptionTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://ftportfolios.com/role/ExpenseExampleFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>falsefalse<div style="display:none">~ http://ftportfolios.com/role/ExpenseExampleFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>truehttp://ftportfolios.com/role/ExpenseExampleFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFundfalsefalse0200308 - Schedule - Expense Example (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) {Transposed}truefalsefalse1falseColumnprimaryElement*4false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsetrue7272falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalse1 YearfalseUSDfalsefalse$2falseColumnprimaryElement*5false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsetrue265265falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse3 YearsfalseUSDfalsefalse$3falseColumnprimaryElement*6false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsetrue556556falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse5 YearsfalseUSDfalsefalse$4falseColumnprimaryElement*7false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsetrue13851385falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse10 YearsfalseUSDfalsefalse$1falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]USDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue7272falsefalsefalsetruefalse2truefalsetrue265265falsefalsefalsetruefalse3truefalsetrue556556falsefalsefalsetruefalse4truefalsetrue13851385falsefalsefalsetruefalseOthernanafalsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]41Expense Example (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*RowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExample.No authoritative reference available.falsefalseExpense Example, With Redemption [Table]15false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PORTFOLIO TURNOVERfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 5 -Subsection instructions falsefalsePortfolio Turnover [Heading]16false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The 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 Fund 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. During the fiscal period November 16, 2009 (inception) through September 30, 2010, the Fund's portfolio turnover rate was 50% of the average value of its portfolio.falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subsection example falsefalsePortfolio Turnover [Text Block]17false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PRINCIPAL INVESTMENT STRATEGIESfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalseStrategy [Heading]18false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The Fund will normally invest at least 90% of its net assets in common stocks that comprise the Index or in depositary receipts that may include American Depositary Receipts ("ADRs"), Global Depositary Receipts ("GDRs"), European Depositary Receipts ("EDRs") or other depositary receipts (collectively "Depositary Receipts") representing securities in the Index. First Trust will seek to match the performance of the Index (before the Fund's fees and expenses).</p><p>The Fund, using an "indexing" investment approach, attempts to replicate, before fees and expenses, the performance of the Index. First Trust seeks a correlation of 0.95 or better (before fees and expenses) between the Fund's performance and the performance of the Index; a figure of 1.00 would represent perfect correlation. First Trust will regularly monitor the Fund's tracking accuracy and will seek to maintain an appropriate correlation.</p><p>The Index is designed to act as a transparent and liquid benchmark for the grid and electric energy infrastructure sector. The Index includes companies that are primarily engaged and involved in electric grid, electric meters and devices, networks, energy storage and management, and enabling software used by the smart grid infrastructure sector.</p><p>Each March and September, Clean Edge, Inc. ("Clean Edge") provides NASDAQ OMX Group, Inc. ("NASDAQ OMX") with a list of companies to be included in the Index. In order to be eligible for inclusion in the Index, the issuer of the security must be classified by Clean Edge as a smart grid, electric infrastructure and/or other grid-related activities company. Clean Edge then screens the companies identified as such using the eligibility criteria described under "Index Information." The list of remaining companies is provided to NASDAQ OMX, which then compiles the Index. NASDAQ OMX determines the respective market-capitalization weighting of each of the securities included in the Index (the "Index Securities") and balances the Index accordingly each March, June, September and December.</p><p>Clean Edge, founded in 2000, is the world's first research and publishing firm devoted to the clean-tech sector. The company, via its publications, events, and online services, helps companies, investors, and governments understand and profit from clean technologies. NASDAQ OMX is the world's largest exchange company with trading, technology and public company service capability spanning six continents.</p>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalseStrategy Narrative [Text Block]19false0rr_RiskHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PRINCIPAL RISKSfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b falsefalseRisk [Heading]20false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>You could lose money by investing in the Fund. 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.</p><p>MARKET RISK. Market risk is the risk that a particular stock owned by the Fund, Shares of the Fund or stocks in general may fall in value. Shares are subject to market fluctuations caused by such factors as economic, political, regulatory or market developments, changes in interest rates and perceived trends in stock prices. Overall stock values could decline generally or could underperform other investments. Companies with smaller market capitalizations are generally subject to additional market risk.</p><p>NON-CORRELATION RISK. The Fund's return may not match the return of the Index for a number of reasons. For example, the Fund incurs operating expenses not applicable to the Index, and may incur costs in buying and selling securities, especially when rebalancing the Fund's portfolio holdings to reflect changes in the composition of the Index. In addition, the Fund's portfolio holdings may not exactly replicate the securities included in the Index or the ratios between the securities included in the Index.</p><p>REPLICATION MANAGEMENT RISK. The Fund is exposed to additional market risk due to its policy of investing principally in the securities included in the Index. As a result of this policy, securities held by the Fund will generally not be bought or sold in response to market fluctuations, and the securities may be issued by companies concentrated in a particular industry. Therefore, the Fund will generally not sell a stock because the stock's issuer is in financial trouble, unless that stock is removed or is anticipated to be removed from the Index.</p><p>NON-DIVERSIFICATION RISK. The Fund is classified as "non-diversified" under the Investment Company Act of 1940, as amended (the "1940 Act"). As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended (the "Code"). The Fund may invest a relatively high percentage of its assets in a limited number of issuers.</p><p>SMART GRID RISK. The Fund will be concentrated in smart grid companies. Smart grid companies can be negatively affected by high costs of research and development, high capital requirements for implementation, uncertain government regulations and input, limited ability of industrial and utility companies to quickly transform their businesses in order to implement new technologies and uncertainty of the ability of new products to penetrate established industries. Smart grid companies are often reliant upon contracts with government and commercial customers which may expire from time to time. Such companies are also affected by the general business conditions within the industrial, utility, information technology and telecommunications sectors and the overall global economy.</p><p>NON-U.S. SECURITIES RISK. The Fund invests in securities of non-U.S. issuers. Such 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; lack of liquidity; excessive taxation; government seizure of assets; different legal or accounting standards; and less government supervision and regulation of exchanges in foreign countries.</p><p>CURRENCY RISK. Because the Fund's NAV is determined on the basis of U.S.dollars, you may lose money if the local currency of a foreign market depreciates against the U.S. dollar, even if the local currency value of a Fund's holdings goes up.</p>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringNarrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph i -Clause instruction -Subsection b falsefalseRisk Narrative [Text Block]21false0rr_BarChartAndPerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00ANNUAL TOTAL RETURNfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalseBar Chart and Performance Table [Heading]22false0rr_PerformanceNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The bar chart and table below illustrate the annual calendar year returns of the Fund based on NAV for the past year as well as the average annual Fund and Index returns for the one year and since inception periods ended December 31, 2010. The bar chart and table provide an indication of the risks of investing in the Fund by showing how the Fund's average annual total returns based on NAV compare to those of the Index and two broad-based securities market indices. See "Total Return Information" for additional performance information regarding the Fund. The Fund's performance information is accessible on the Fund's website at www.ftportfolios.com.</p><p>Returns before taxes do not reflect the effects of any income or capital gains taxes. All after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of any state or local tax. Returns after taxes on distributions reflect the taxed return on the payment of dividends and capital gains. Returns after taxes on distributions and sale of Shares assume you sold your Shares at period end, and, therefore, are also adjusted for any capital gains or losses incurred. Returns for the market indices do not include expenses, which are deducted from Fund returns, or taxes.</p><p>Your own actual after-tax returns will depend on your specific tax situation and may differ from what is shown here. After-tax returns are not relevant to investors who hold Fund Shares in tax-deferred accounts such as individual retirement accounts (IRAs) or employee-sponsored retirement plans.</p>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalsePerformance Narrative [Text Block]23false0rr_AnnualReturnCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00FIRST TRUST NASDAQ(R) CLEAN EDGE(R) SMART GRID INFRASTRUCTURE INDEX FUND--TOTAL RETURNSfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. Provide annual total returns beginning with the earliest calendar year. Calculate annual returns using the Instructions to Item 8(a), except that the calculations should be based on calendar years. If a Fund's shares are sold subject to a sales load or account fees, state that sales loads or account fees are not reflected in the bar chart and that, if these amounts were reflected, returns would be less than those shown. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets). When a Multiple Class Fund offering one or more Classes offers a new Class in a prospectus that does not offer the shares of any other Class, include the bar chart with annual total returns for any other existing Class for the first year that the Class is offered. Explain in a footnote that the returns are for a Class that is not offered in the prospectus that would have substantially similar annual returns because the shares are invested in the same portfolio of securities and the annual returns would differ only to the extent that the Classes do not have the same expenses. Include return information for the other Class reflected in the bar chart in the performance table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit b -Subsection b falsefalseAnnual Return Caption [Text]24false0rr_BarChartTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://ftportfolios.com/role/AnnualTotalReturnsBarChartFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>falsefalseBarChart5.jpg<div style="display:none">~ http://ftportfolios.com/role/AnnualTotalReturnsBarChartFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * column rr_ProspectusShareClassAxis compact * row compact * row dei_LegalEntityAxis compact ftetf1364608_S000026919_Member ~</div>falsehttp://ftportfolios.com/role/AnnualTotalReturnsBarChartFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFundfalsefalse0200508 - Schedule - Annual Total Returns (Bar Chart) (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund)truefalsefalse1falseColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxis*ColumnunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*4false0rr_AnnualReturn2010rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.0020-0.0020falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 20100rr_AnnualReturn2010truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.0020-0.0020falsefalsefalsetruefalseOthernanafalsefalseAnnual Return 201011Annual Total Returns (Bar Chart) (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No authoritative reference available.falsefalseBar Chart [Table]25false0rr_BarChartClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00During the year ended December 31, 2010, the Fund's highest and lowest calendar quarter returns were 10.90% and -10.74%, respectively, for the quarters ended September 30, 2010 and June 30, 2010. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseBar Chart Closing [Text Block]26false0rr_AverageAnnualReturnCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2010falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 5 -Subsection b falsefalseCaption27false0rr_PerformanceTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://ftportfolios.com/role/AverageAnnualTotalReturnsFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * row compact * row rr_ProspectusShareClassAxis compact * row rr_PerformanceMeasureAxis compact * row dei_LegalEntityAxis compact ftetf1364608S000026919_Member ~ Rows and columns are reversed here due to transposition</div>falsefalse<div style="display:none">~ http://ftportfolios.com/role/AverageAnnualTotalReturnsFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFund column compact * row compact * row rr_ProspectusShareClassAxis compact * row rr_PerformanceMeasureAxis compact * row dei_LegalEntityAxis compact ftetf1364608S000026919_Member ~ Rows and columns are reversed here due to transposition</div>truehttp://ftportfolios.com/role/AverageAnnualTotalReturnsFirstTrustNasdaqCleanEdgeSmartGridInfrastructureIndexFundfalsefalse0200608 - Schedule - Average Annual Total Returns (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) {Transposed}truefalsefalse1falseColumnprimaryElement*4false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Return Before Taxesfalsefalsefalsetruefalse2falsetruefalse00Return After Taxes on Distributionsfalsefalsefalsetruefalse3falsetruefalse00Return After Taxes on Distributions and Sale of Sharesfalsefalsefalsetruefalse4falsetruefalse00NASDAQ OMX(R) Clean Edge(R) Smart Grid Infrastructure Index(SM)falsefalsefalsetruefalse5falsetruefalse00S&P 1500 Industrials Indexfalsefalsefalsetruefalse6falsetruefalse00Russell 3000(R) Indexfalsefalsefalsetruefalse7falsetruefalse00Russell 3000(R) Indexfalsefalsefalsetruefalse8falsetruefalse00MSCI World Industrials Indexfalsefalsefalsetruefalse9falsetruefalse00MSCI World Industrials IndexfalsefalsefalsetruefalseOtherxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalseLabelfalseUSDfalsefalse$2falseColumnprimaryElement*5false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue-0.0020-0.0020falsefalsefalsetruefalse2truetruetrue-0.0034-0.0034falsefalsefalsetruefalse3truetruetrue-0.0014-0.0014falsefalsefalsetruefalse4truetruetrue0.00710.0071falsefalsefalsetruefalse5truetruetrue0.27240.2724falsefalsefalsetruefalse6truetruetrue0.16930.1693falsefalsefalsetruefalse7truetruetrue0.16930.1693falsefalsefalsetruefalse8truetruetrue0.23350.2335falsefalsefalsetruefalse9truetruetrue0.23350.2335[1]falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalse1 YearfalseUSDfalsefalse$3falseColumnprimaryElement*6false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05610.0561falsefalsefalsetruefalse2truetruetrue0.05470.0547falsefalsefalsetruefalse3truetruetrue0.04680.0468falsefalsefalsetruefalse4truetruetrue0.06620.0662falsefalsefalsetruefalse5truetruetrue0.23760.2376falsefalsefalsetruefalse6truetruetrue0.14660.1466falsefalsefalsetruefalse7truetruetrue0.16260.1626falsefalsefalsetruefalse8truetruetrue0.18890.1889falsefalsefalsetruefalse9truetruetrue0.19730.1973[1]falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalseSince InceptionfalseUSDfalsefalse$4falseColumnprimaryElement*7false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002009-11-16falsefalsetruetruefalse2falsetruefalse002009-11-16falsefalsetruetruefalse3falsetruefalse002009-11-16falsefalsetruetruefalse4falsetruefalse002009-11-16falsefalsetruetruefalse5falsetruefalse002009-11-16falsefalsetruetruefalse6falsetruefalse002008-10-13falsefalsetruetruefalse7falsetruefalse002009-11-16falsefalsetruetruefalse8falsetruefalse002008-10-13falsefalsetruetruefalse9falsetruefalse002009-11-16[1]falsefalsetruetruefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseInception DatefalseUSDfalsefalse$1falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseReturn Before Taxes [Member]rr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_ReturnBeforeTaxesMemberrr_PerformanceMeasureAxisexplicitMembertruefalseSeriesdei_LegalEntityAxisdei_EntityDomaindei_LegalEntityAxisexplicitMemberFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]Return Before Taxes [Member]SeriesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Return Before TaxesReturn Before Taxesfalsefalsefalsetruefalse2truetruetrue-0.0020-0.0020falsefalsefalsetruefalse3truetruetrue0.05610.0561falsefalsefalsetruefalse4falsetruefalse002009-11-162009-11-16falsefalsetruetruefalseOthernanafalsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member] Return Before Taxes [Member]2falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseReturn After Taxes on Distributionsrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsMemberrr_PerformanceMeasureAxisexplicitMembertruefalseSeriesdei_LegalEntityAxisdei_EntityDomaindei_LegalEntityAxisexplicitMemberFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]Return After Taxes on DistributionsSeriesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Return After Taxes on DistributionsReturn After Taxes on Distributionsfalsefalsefalsetruefalse2truetruetrue-0.0034-0.0034falsefalsefalsetruefalse3truetruetrue0.05470.0547falsefalsefalsetruefalse4falsetruefalse002009-11-162009-11-16falsefalsetruetruefalseOthernanafalsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member] Return After Taxes on Distributions3falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_S000026919Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseReturn After Taxes on Distributions and Sale of Sharesrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsAndSalesMemberrr_PerformanceMeasureAxisexplicitMembertruefalseSeriesdei_LegalEntityAxisdei_EntityDomaindei_LegalEntityAxisexplicitMemberFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member]Return After Taxes on Distributions and Sale of SharesSeriesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Return After Taxes on Distributions and Sale of SharesReturn After Taxes on Distributions and Sale of Sharesfalsefalsefalsetruefalse2truetruetrue-0.0014-0.0014falsefalsefalsetruefalse3truetruetrue0.04680.0468falsefalsefalsetruefalse4falsetruefalse002009-11-162009-11-16falsefalsetruetruefalseOthernanafalsefalseFirst Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member] Return After Taxes on Distributions and Sale of Shares4falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseNASDAQ OMX(R) Clean Edge(R) Smart Grid Infrastructure Index(SM) [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_NasdaqOmxCleanEdgeSmartGridInfrastructureIndexMemberdei_DocumentInformationDocumentAxisexplicitMembertruefalsePerformance Measurerr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMembertruefalseSeriesdei_LegalEntityAxisdei_EntityDomaindei_LegalEntityAxisexplicitMemberNASDAQ OMX(R) Clean Edge(R) Smart Grid Infrastructure Index(SM) [Member]Performance MeasureSeriesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00NASDAQ OMX(R) Clean Edge(R) Smart Grid Infrastructure Index(SM)NASDAQ OMX(R) Clean Edge(R) Smart Grid Infrastructure Index(SM)falsefalsefalsetruefalse2truetruetrue0.00710.0071falsefalsefalsetruefalse3truetruetrue0.06620.0662falsefalsefalsetruefalse4falsetruefalse002009-11-162009-11-16falsefalsetruetruefalseOthernanafalsefalseNASDAQ OMX(R) Clean Edge(R) Smart Grid Infrastructure Index(SM) [Member]5falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseS&P 1500 Industrials Index [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_SAndPOneThousandFiveHundredIndustrialsIndexMemberdei_DocumentInformationDocumentAxisexplicitMembertruefalsePerformance Measurerr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMembertruefalseSeriesdei_LegalEntityAxisdei_EntityDomaindei_LegalEntityAxisexplicitMemberS&P 1500 Industrials Index [Member]Performance MeasureSeriesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00S&P 1500 Industrials IndexS&P 1500 Industrials Indexfalsefalsefalsetruefalse2truetruetrue0.27240.2724falsefalsefalsetruefalse3truetruetrue0.23760.2376falsefalsefalsetruefalse4falsetruefalse002009-11-162009-11-16falsefalsetruetruefalseOthernanafalsefalseS&P 1500 Industrials Index [Member]6falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseRussell 3000(R) Index [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_RussellThreeThousandRIndexMemberdei_DocumentInformationDocumentAxisexplicitMembertruefalsePerformance Measurerr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMembertruefalseSeriesdei_LegalEntityAxisdei_EntityDomaindei_LegalEntityAxisexplicitMemberRussell 3000(R) Index [Member]Performance MeasureSeriesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Russell 3000(R) IndexRussell 3000(R) Indexfalsefalsefalsetruefalse2truetruetrue0.16930.1693falsefalsefalsetruefalse3truetruetrue0.14660.1466falsefalsefalsetruefalse4falsetruefalse002008-10-132008-10-13falsefalsetruetruefalseOthernanafalsefalseRussell 3000(R) Index [Member]7falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseRussell 3000(R) Index [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_RussellThreeThousandRIndexMemberdei_DocumentInformationDocumentAxisexplicitMembertruefalsePerformance Measurerr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberfalsefalseInception period since 11/16/2009 [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_InceptionPeriodOneMemberdei_LegalEntityAxisexplicitMemberRussell 3000(R) Index [Member]Performance MeasureInception period since 11/16/2009 [Member]Standard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Russell 3000(R) IndexRussell 3000(R) Indexfalsefalsefalsetruefalse2truetruetrue0.16930.1693falsefalsefalsetruefalse3truetruetrue0.16260.1626falsefalsefalsetruefalse4falsetruefalse002009-11-162009-11-16falsefalsetruetruefalseOthernanafalsefalseRussell 3000(R) Index [Member] Inception period since 11/16/2009 [Member]8falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseMSCI World Industrials Index [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_MsciWorldIndustrialsIndexMemberdei_DocumentInformationDocumentAxisexplicitMembertruefalsePerformance Measurerr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMembertruefalseSeriesdei_LegalEntityAxisdei_EntityDomaindei_LegalEntityAxisexplicitMemberMSCI World Industrials Index [Member]Performance MeasureSeriesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00MSCI World Industrials IndexMSCI World Industrials Indexfalsefalsefalsetruefalse2truetruetrue0.23350.2335falsefalsefalsetruefalse3truetruetrue0.18890.1889falsefalsefalsetruefalse4falsetruefalse002008-10-132008-10-13falsefalsetruetruefalseOthernanafalsefalseMSCI World Industrials Index [Member]9falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*duration2010-02-01T00:00:002011-01-31T00:00:00falsefalseMSCI World Industrials Index [Member]dei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_MsciWorldIndustrialsIndexMemberdei_DocumentInformationDocumentAxisexplicitMembertruefalsePerformance Measurerr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberfalsefalseInception period since 11/16/2009 [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiftetf1364608_InceptionPeriodOneMemberdei_LegalEntityAxisexplicitMemberMSCI World Industrials Index [Member]Performance MeasureInception period since 11/16/2009 [Member]Standard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00MSCI World Industrials IndexMSCI World Industrials Indexfalsefalsefalsetruefalse2truetruetrue0.23350.2335[1]falsefalsefalsetruefalse3truetruetrue0.19730.1973[1]falsefalsefalsetruefalse4falsetruefalse002009-11-162009-11-16[1]falsefalsetruetruefalseOthernanafalsefalseMSCI World Industrials Index [Member] Inception period since 11/16/2009 [Member]1The broad-based securities market index is changing from S and P 1500 Industrials Index to MSCI World Industrials Index because the MSCI World Industrials Index better reflects the composition of the Fund.49Average Annual Total Returns (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) UnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*RowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxis*Rowrr_PerformanceMeasureAxisAxis*Rowdei_LegalEntityAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No authoritative reference available.falsefalsePerformance [Table]125Risk/Return Summary (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund) (First Trust NASDAQ (R) Clean Edge (R) Smart Grid Infrastructure Index Fund [Member])UnKnownUnKnownUnKnownUnKnownfalsetrue