2.4.0.8010000 - Document - Risk/Return Summary {Unlabeled}falsefalsetrue1false falsefalseAsOf2013-07-22_S000024215Memberhttp://www.sec.gov/CIK0001364608duration2013-07-22T00:00:002013-07-22T00:00:001false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00First Trust ISE Global Engineering and Construction Index Fundfalsefalsefalse1false truefalseAsOf2013-07-22_S000024215Memberhttp://www.sec.gov/CIK0001364608duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFLMFONEGRID_S000024215Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000024215Memberdei_LegalEntityAxisexplicitMembernanafalse0First Trust ISE Global Engineering and Construction Index Fund2false 2rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>SUMMARY INFORMATION</p>falsefalsefalsexbrli: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 false0Risk/Return [Heading]3false 2rr_ObjectiveHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>INVESTMENT OBJECTIVE</p>falsefalsefalsexbrli: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 false0Objective [Heading]4false 2rr_ObjectivePrimaryTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The First Trust ISE Global Engineering and Construction 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 ISE Global Engineering and Construction(TM) Index (the "Index").</p>falsefalsefalseus-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 false0Objective, Primary [Text Block]5false 2rr_ExpenseHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>FEES AND EXPENSES OF THE FUND</p>falsefalsefalsexbrli: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 false0Expense [Heading]6false 2rr_ExpenseNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The 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.</p>falsefalsefalseus-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 false0Expense Narrative [Text Block]7false 2rr_ShareholderFeesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>SHAREHOLDER FEES (fees paid directly from your investment)</p>falsefalsefalsexbrli: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 false0Shareholder Fees Caption [Text]8false 2rr_ShareholderFeesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/ShareholderFeesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/ShareholderFeesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/ShareholderFeesData020010 - Schedule - Shareholder Feestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust ISE Global Engineering and Construction Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000024215Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust ISE Global Engineering and Construction Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000071160Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust ISE Global Engineering and Construction Index FundFirst Trust ISE Global Engineering and Construction Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*3false 2rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) 0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue00falsefalsefalserr: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 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)falseShareholder Fees UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet11001105ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No definition available.false0Shareholder Fees [Table]9false 2rr_OperatingExpensesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>ANNUAL FUND OPERATING EXPENSES (Expenses that you pay each year as a percentage of the value of your investment)</p>falsefalsefalsexbrli: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 false0Operating Expenses Caption [Text]10false 2rr_AnnualFundOperatingExpensesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/OperatingExpensesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/OperatingExpensesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/OperatingExpensesData020020 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust ISE Global Engineering and Construction Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000024215Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust ISE Global Engineering and Construction Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000071160Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust ISE Global Engineering and Construction Index FundFirst Trust ISE Global Engineering and Construction Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*3false 2rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Management Fees 0rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00400.0040falsefalsefalserr: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 false0Management Fees2falseRowprimaryElement*4false 2rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Distribution and Service (12b-1) Fees 0rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse[1]1truetruetrue0.00000.0000falsefalsefalserr: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 false0Distribution and Service (12b-1) Fees3falseRowprimaryElement*5false 2rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Other Expenses 0rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00310.0031falsefalsefalserr: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 false0Other Expenses4falseRowprimaryElement*6false 2rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Total Annual Fund Operating Expenses 0rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00710.0071falsefalsefalserr: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 false0Total Annual Fund Operating Expenses5falseRowprimaryElement*7false 2rr_FeeWaiverOrReimbursementOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Fee Waiver and Expense Reimbursement 0rr_FeeWaiverOrReimbursementOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse[2]1truetruetrue-0.0001-0.0001falsefalsefalserr: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 false0Fee Waiver and Expense Reimbursement6falseRowprimaryElement*8false 2rr_NetExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Total Net Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement 0rr_NetExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00700.0070falsefalsefalserr: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 false0Total Net Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement1Although the Fund has adopted a 12b-1 plan that permits it to pay up to 0.25% per annum, it will not pay 12b-1 fees at any time before January 31, 2014.2First 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 0.70% of its average daily net assets per year at least until January 31, 2014. Expenses borne by First Trust are subject to reimbursement by the Fund for 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 31, 2014 upon 60 days' written notice.falseAnnual Fund Operating Expenses UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet160516010ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No definition available.false0Annual Fund Operating Expenses [Table]11false 2rr_ExpenseExampleHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>EXAMPLE</p>falsefalsefalsexbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions false0Expense Example [Heading]12false 2rr_ExpenseExampleNoRedemptionNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<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 annual operating expenses remain at current levels until January 31, 2014. 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, 2014. 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 31, 2014. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</p>falsefalsefalseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExampleNoRedemption.No definition available.false0Expense Example, No Redemption Narrative [Text Block]13false 2rr_ExpenseExampleNoRedemptionTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>truehttp://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption020040 - Schedule - Expense Example, No Redemption {Transposed}truefalsefalse1falseColumnprimaryElement*3false 2rr_ExpenseExampleNoRedemptionYear01rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example false21 Year USDfalsefalse$2falseColumnprimaryElement*4false 2rr_ExpenseExampleNoRedemptionYear03rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example false23 Years USDfalsefalse$3falseColumnprimaryElement*5false 2rr_ExpenseExampleNoRedemptionYear05rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions false25 Years USDfalsefalse$4falseColumnprimaryElement*6false 2rr_ExpenseExampleNoRedemptionYear10rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions false210 Years USDfalsefalse$1falseRowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust ISE Global Engineering and Construction Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000024215Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust ISE Global Engineering and Construction Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000071160Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust ISE Global Engineering and Construction Index FundFirst Trust ISE Global Engineering and Construction Index FundUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170 0truefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue7272falsefalsefalse2truefalsetrue271271falsefalsefalse3truefalsetrue497497falsefalsefalse4truefalsetrue11461146falsefalsefalsenanafalse0First Trust ISE Global Engineering and Construction Index FundfalseExpense Example, No Redemption (USD $)UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet413041020ColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExampleNoRedemption.No definition available.false0Expense Example, No Redemption [Table]14false 2rr_PortfolioTurnoverHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PORTFOLIO TURNOVER</p>falsefalsefalsexbrli: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 false0Portfolio Turnover [Heading]15false 2rr_PortfolioTurnoverTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when 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 most recent fiscal year, the Fund's portfolio turnover rate was 22% of the average value of its portfolio.</p>falsefalsefalseus-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 false0Portfolio Turnover [Text Block]16false 2rr_StrategyHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PRINCIPAL INVESTMENT STRATEGIES</p>falsefalsefalsexbrli: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 false0Strategy [Heading]17false 2rr_StrategyNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The Fund will normally invest at least 90% of its net assets (plus the amount of any borrowings for investment purposes) 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 developed and owned by the International Securities Exchange, LLC(R) ("ISE" or "Index Provider"), in consultation with Standard &#38; Poor's, a Division of The McGraw-Hill Companies, Inc. ("S&#38;P"), which calculates and maintains the Index. The Index provides a benchmark for investors interested in tracking public companies throughout the world that are active in the engineering and construction industries, based on analysis of the products and services offered by those companies. The Index specifically targets companies that are engaged in large civil and capital projects such as infrastructure, utilities, transportation, telecommunications, commercial, residential, and commerce facilities and whose roles are within the engineering, designing, planning, consulting, project managing, and/or constructing of these projects. To be included in the Index, a company must receive at least 70% of revenues from these types of services and projects based on the reportable segment/division from its most recent annual report.</p> <p>The Fund intends to invest entirely in securities included in the Index; however, there may also be instances in which the Fund may be underweighted or overweighted in certain securities in the Index, not invest in certain securities included in the Index, purchase securities not in the Index that are appropriate to substitute for certain securities in the Index or utilize various combinations of the above techniques in seeking to track the Index.</p>falsefalsefalseus-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 false0Strategy Narrative [Text Block]18false 2rr_RiskHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PRINCIPAL RISKS</p>falsefalsefalsexbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b false0Risk [Heading]19false 2rr_RiskNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<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.</p> <p>SMALLER COMPANY RISK. The Fund invests in small and mid capitalization companies. Such companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than larger, more established companies as a result of several factors, including limited trading volumes, products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than larger, more established companies.</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. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly concentrated in certain issuers.</p> <p>ENGINEERING AND CONSTRUCTION RISK. The Fund invests in the securities of engineering and construction companies. Risks associated with investing in these companies include the general state of the economy, demand for their specific products or services, changes in government spending, zoning laws, interest rates, declines in real estate values, environmental damage and product liability claims. In addition, they may also be significantly affected by overall capital spending levels, economic cycles, technical obsolescence, delays in modernization, labor relations, government regulations and e-commerce initiatives.</p> <p>INDUSTRIALS SECTOR RISK. The Fund invests in the securities of companies in the industrials sector. Many companies in this sector convert unfinished goods into finished durables used to manufacture other goods or provide services. Some industries included in this sector are electrical equipment and components, industrial products, manufactured housing and telecommunications equipment. General risks of these companies include the general state of the economy, intense competition, consolidation, domestic and international politics, excess capacity and consumer demand and spending trends. In addition, they may also be significantly affected by overall capital spending levels, economic cycles, technical obsolescence, delays in modernization, labor relations, government regulations and e-commerce initiatives.</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>JAPAN RISK. The Fund invests in the stock of companies operating in Japan. Because Japan's economy and equity market share a strong correlation with the U.S. markets, the Japanese economy may be affected by economic problems in the U.S. Japan also has a growing economic relationship with China and other Southeast Asian countries, and thus Japan's economy may also be affected by economic, political or social instability in those countries. Despite a strengthening in the economic relationship between Japan and China, the countries' political relationship has at times been strained in recent years. Should political tension increase, it could adversely affect the economy and destabilize the region as a whole. Japan also remains heavily dependent on oil imports, and higher commodity prices could therefore have a negative impact on the economy. Japanese securities may also be subject to lack of liquidity; excessive taxation; government seizure of assets; different legal or accounting standards and less government supervision and regulation of exchanges than in the United States. Furthermore, the natural disasters that have impacted Japan and the ongoing recovery efforts have had a negative affect on Japan's economy, and may continue to do so.</p> <p>DEPOSITARY RECEIPTS RISK. Depositary receipts may be less liquid than the underlying shares in their primary trading market. Any distributions paid to the holders of depositary receipts are usually subject to a fee charged by the depositary. Holders of depositary receipts may have limited voting rights, and investment restrictions in certain countries may adversely impact the value of depositary receipts because such restrictions may limit the ability to convert equity shares into depositary receipts and vice versa. Such restrictions may cause equity shares of the underlying issuer to trade at a discount or premium to the market price of the depositary receipts.</p> <p>CURRENCY RISK. Because the Fund's NAV is determined on the basis of U.S. dollars and the Fund invests in foreign securities, 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 the Fund's holdings goes up.</p>falsefalsefalseus-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 false0Risk Narrative [Text Block]20false 2rr_BarChartAndPerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>ANNUAL TOTAL RETURN</p>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b false0Bar Chart and Performance Table [Heading]21false 2rr_PerformanceNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The bar chart and table below illustrate the annual calendar year returns of the Fund based on NAV for the past four years as well as the average annual Fund and Index returns for the one year and since inception periods ended December 31, 2012. The bar chart and table provide an indication of the risks of investing in the Fund by showing changes in the Fund's performance from year-to-year and by showing how the Fund's average annual total returns based on NAV compare to those of the Index, the Russell 3000(R) Index, which is a broad-based securities market index, and a specialized securities market index. 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>falsefalsefalseus-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 false0Performance Narrative [Text Block]22false 2rr_BarChartHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>FIRST TRUST ISE GLOBAL ENGINEERING AND CONSTRUCTION INDEX FUND--TOTAL RETURNS</p>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b false0Bar Chart [Heading]23false 2rr_BarChartTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/BarChartData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalseBarChart1.jpg<div style="display: none">~ http://xbrl.sec.gov/rr/role/BarChartData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/BarChartData020050 - Schedule - Annual Total Returnstruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust ISE Global Engineering and Construction Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000024215Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust ISE Global Engineering and Construction Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000071160Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust ISE Global Engineering and Construction Index FundFirst Trust ISE Global Engineering and Construction Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*3false3false 2rr_AnnualReturn2009rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.25440.2544falsefalsefalse2falsetruefalse00falsefalsefalse3falsetruefalse00falsefalsefalsexbrli: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 instructions -Clause 3 -Exhibit a -Subsection b false0Annual Return 2009 2rr_AnnualReturn2009rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalsexbrli: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 instructions -Clause 3 -Exhibit a -Subsection b false0Annual Return 2009 0rr_AnnualReturn2009rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.25440.2544falsefalsefalsexbrli: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 instructions -Clause 3 -Exhibit a -Subsection b false0Annual Return 20092falseRowprimaryElement*4false4false 2rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.18230.1823falsefalsefalse2falsetruefalse00falsefalsefalse3truetruefalse-0.0020-0.0020falsefalsefalsexbrli: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 false0Annual Return 2010 2rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalsexbrli: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 false0Annual Return 2010 0rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.18230.1823falsefalsefalsexbrli: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 false0Annual Return 20103falseRowprimaryElement*5false5false 2rr_AnnualReturn2011rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.1744-0.1744falsefalsefalse2falsetruefalse00falsefalsefalse3truetruefalse-0.2090-0.2090falsefalsefalsexbrli: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 instructions -Clause 3 -Exhibit a -Subsection b false0Annual Return 2011 2rr_AnnualReturn2011rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalsexbrli: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 instructions -Clause 3 -Exhibit a -Subsection b false0Annual Return 2011 0rr_AnnualReturn2011rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.1744-0.1744falsefalsefalsexbrli: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 instructions -Clause 3 -Exhibit a -Subsection b false0Annual Return 20114falseRowprimaryElement*6false6false 2rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.19210.1921falsefalsefalse2truetruefalse0.07440.0744falsefalsefalse3truetruefalse0.19690.1969falsefalsefalsexbrli: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 false0Annual Return 2012 2rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalsexbrli: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 false0Annual Return 2012 0rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.19210.1921falsefalsefalsexbrli: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 false0Annual Return 2012falseAnnual Total Returns UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet14031408ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No definition available.false0Bar Chart [Table]24false 2rr_BarChartClosingTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>During the four-year period ended December 31, 2012, the Fund's highest and lowest calendar quarter returns were 28.36% and -24.67%, respectively, for the quarters ended June 30, 2009 and September 30, 2011. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.</p>falsefalsefalseus-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 false0Bar Chart Closing [Text Block]25false 2rr_PerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2012</p>falsefalsefalsexbrli: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 3 -Exhibit c -Subsection b false0Performance Table Heading26false 2rr_PerformanceTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/PerformanceTableData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/PerformanceTableData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000024215Member column rr_ProspectusShareClassAxis compact * row 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and Sales4falseRowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust ISE Global Engineering and Construction Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000024215Memberdei_LegalEntityAxisexplicitMembertruefalse[ShareClassDomain]rr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseISE Global Engineering and Construction(TM) Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_ISEGlobalEngineeringConstructionIndexMemberrr_PerformanceMeasureAxisexplicitMemberFirst Trust ISE Global Engineering and Construction Index Fund[ShareClassDomain]ISE Global Engineering and Construction(TM) IndexRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 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Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_MSCIWorldIndustrialsIndexMemberrr_PerformanceMeasureAxisexplicitMemberFirst Trust ISE Global Engineering and Construction Index Fund[ShareClassDomain]MSCI World Industrials IndexRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 0truefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.16020.1602falsefalsefalse2truetruetrue0.11170.1117falsefalsefalse3falsetruefalse002008-10-13falsefalsetruenanafalse0First Trust ISE Global Engineering and Construction Index Fund MSCI World Industrials IndexfalseAverage Annual Total Returns UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet36121536051ColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000024215MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No definition available.false0Performance [Table]27false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00First Trust NASDAQ CEA Smartphone Index Fundfalsefalsefalse2false truefalseAsOf2013-07-22_S000030172Memberhttp://www.sec.gov/CIK0001364608duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFLMFONEGRID_S000030172Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000030172Memberdei_LegalEntityAxisexplicitMembernanafalse0First Trust NASDAQ CEA Smartphone Index Fund28false 2rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>SUMMARY INFORMATION</p>falsefalsefalsexbrli: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 false0Risk/Return [Heading]29false 2rr_ObjectiveHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>INVESTMENT OBJECTIVE</p>falsefalsefalsexbrli: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 false0Objective [Heading]30false 2rr_ObjectivePrimaryTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The First Trust NASDAQ CEA Smartphone 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 CEA Smartphone Index(SM) (the "Index").</p>falsefalsefalseus-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 false0Objective, Primary [Text Block]31false 2rr_ExpenseHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>FEES AND EXPENSES OF THE FUND</p>falsefalsefalsexbrli: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 false0Expense [Heading]32false 2rr_ExpenseNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The 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.</p>falsefalsefalseus-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 false0Expense Narrative [Text Block]33false 2rr_ShareholderFeesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>SHAREHOLDER FEES (fees paid directly from your investment)</p>falsefalsefalsexbrli: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 false0Shareholder Fees Caption [Text]34false 2rr_ShareholderFeesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/ShareholderFeesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/ShareholderFeesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/ShareholderFeesData020010 - Schedule - Shareholder Feestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ CEA Smartphone Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000030172Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ CEA Smartphone Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000092838Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ CEA Smartphone Index FundFirst Trust NASDAQ CEA Smartphone Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*3false 2rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) 0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue00falsefalsefalserr: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 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)falseShareholder Fees UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet11001105ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No definition available.false0Shareholder Fees [Table]35false 2rr_OperatingExpensesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>ANNUAL FUND OPERATING EXPENSES (Expenses that you pay each year as a percentage of the value of your investment)</p>falsefalsefalsexbrli: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 false0Operating Expenses Caption [Text]36false 2rr_AnnualFundOperatingExpensesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/OperatingExpensesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/OperatingExpensesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/OperatingExpensesData020020 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ CEA Smartphone Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000030172Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ CEA Smartphone Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000092838Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ CEA Smartphone Index FundFirst Trust NASDAQ CEA Smartphone Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*3false 2rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Management Fees 0rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00700.0070falsefalsefalserr: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 false0Management Fees2falseRowprimaryElement*4false 2rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Distribution and Service (12b-1) Fees 0rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse[1]1truetruetrue0.00000.0000falsefalsefalserr: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 false0Distribution and Service (12b-1) Fees3falseRowprimaryElement*5false 2rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Other Expenses 0rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalserr: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 false0Other Expenses4falseRowprimaryElement*6false 2rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Total Annual Fund Operating Expenses 0rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00700.0070falsefalsefalserr: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 false0Total Annual Fund Operating Expenses1Although the Fund has adopted a 12b-1 plan that permits it to pay up to 0.25% per annum, it will not pay 12b-1 fees at any time before January 31, 2014.falseAnnual Fund Operating Expenses UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet140516010ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No definition available.false0Annual Fund Operating Expenses [Table]37false 2rr_ExpenseExampleHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>EXAMPLE</p>falsefalsefalsexbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions false0Expense Example [Heading]38false 2rr_ExpenseExampleNoRedemptionNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<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 annual operating expenses remain at current levels until January 31, 2014. 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, 2014. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</p>falsefalsefalseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExampleNoRedemption.No definition available.false0Expense Example, No Redemption Narrative [Text Block]39false 2rr_ExpenseExampleNoRedemptionTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>truehttp://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption020040 - Schedule - Expense Example, No Redemption {Transposed}truefalsefalse1falseColumnprimaryElement*3false 2rr_ExpenseExampleNoRedemptionYear01rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example false21 Year USDfalsefalse$2falseColumnprimaryElement*4false 2rr_ExpenseExampleNoRedemptionYear03rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example false23 Years USDfalsefalse$3falseColumnprimaryElement*5false 2rr_ExpenseExampleNoRedemptionYear05rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions false25 Years USDfalsefalse$4falseColumnprimaryElement*6false 2rr_ExpenseExampleNoRedemptionYear10rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions false210 Years USDfalsefalse$1falseRowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ CEA Smartphone Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000030172Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ CEA Smartphone Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000092838Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ CEA Smartphone Index FundFirst Trust NASDAQ CEA Smartphone Index FundUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170 0truefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue7272falsefalsefalse2truefalsetrue269269falsefalsefalse3truefalsetrue492492falsefalsefalse4truefalsetrue11351135falsefalsefalsenanafalse0First Trust NASDAQ CEA Smartphone Index FundfalseExpense Example, No Redemption (USD $)UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet413041020ColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExampleNoRedemption.No definition available.false0Expense Example, No Redemption [Table]40false 2rr_PortfolioTurnoverHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PORTFOLIO TURNOVER</p>falsefalsefalsexbrli: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 false0Portfolio Turnover [Heading]41false 2rr_PortfolioTurnoverTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when 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 most recent fiscal year, the Fund's portfolio turnover rate was 35% of the average value of its portfolio.</p>falsefalsefalseus-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 false0Portfolio Turnover [Text Block]42false 2rr_StrategyHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PRINCIPAL INVESTMENT STRATEGIES</p>falsefalsefalsexbrli: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 false0Strategy [Heading]43false 2rr_StrategyNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The Fund will normally invest at least 90% of its net assets (plus the amount of any borrowings for investment purposes) 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 Advisors L.P. ("First Trust"), the Fund's investment advisor, 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.</p> <p>The Index is owned by The NASDAQ OMX Group, Inc. (the "Index Provider"). The Index Provider and the Consumer Electronics Association have jointly developed the eligibility and selection criteria and rules for the Index. The Index is calculated and maintained by the Index Provider. The Index is designed to track the performance of companies engaged in the Smartphone segment of the telecommunications and technology sectors. The Index includes companies primarily involved in the building, design and distribution of handsets, hardware, software and mobile networks associated with the development, sale and usage of Smartphones. The Index Provider defines a Smartphone as a wireless, mobile communication device offering advanced capabilities and functionalities, including web access, through the use of an identifiable operating system.</p> <p>The Index uses a modified equal dollar weighting methodology. The Index Provider evaluates the Index components semi-annually in March and September of each year for eligibility, using market data through the end of February and August, respectively. Eligible components for the Index are identified as such using the eligibility criteria set forth in this Prospectus under "Index Information." Changes to the Index are made effective after the close of trading on the third Friday in March and September. The Index is rebalanced quarterly, each March, June, September and December. As of December 31, 2012, there were 64 securities that comprised the Index.</p> <p>The Fund intends to invest entirely in securities included in the Index; however, there may also be instances in which the Fund may be underweighted or overweighted in certain securities in the Index, not invest in certain securities included in the Index, purchase securities not in the Index that are appropriate to substitute for certain securities in the Index or utilize various combinations of the above techniques in seeking to track the Index.</p>falsefalsefalseus-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 false0Strategy Narrative [Text Block]44false 2rr_RiskHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PRINCIPAL RISKS</p>falsefalsefalsexbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b false0Risk [Heading]45false 2rr_RiskNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<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.</p> <p>SMALLER COMPANY RISK. The Fund invests in small and mid capitalization companies. Such companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than larger, more established companies as a result of several factors, including limited trading volumes, products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than larger, more established companies.</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. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly concentrated in certain issuers.</p> <p>INFORMATION TECHNOLOGY COMPANIES RISK. The Fund invests in the securities of information technology companies. Information technology companies are generally subject to the risks of rapidly changing technologies, short product life cycles, fierce competition, aggressive pricing and reduced profit margins, loss of patent, copyright and trademark protections, cyclical market patterns, evolving industry standards and frequent new product introductions. Information technology companies may be smaller and less experienced companies, with limited product lines, markets or financial resources and fewer experienced management or marketing personnel. Information technology company stocks, particularly those involved with the Internet, have experienced extreme price and volume fluctuations that often have been unrelated to their operating performance.</p> <p>SMARTPHONE INDUSTRY RISK. The Fund will be invested in securities of companies in the smartphone industry. The smartphone industry is characterized by intense competition and new market entrants, which could negatively impact profit margins and overall revenues of the companies involved in the industry. Smartphone companies are generally subject to the risks of rapidly changing technologies, short product life cycles, fierce competition, aggressive pricing and reduced profit margins, the loss of patent, copyright and trademark protections, cyclical market patterns, evolving industry standards, and frequent new product introductions. Smartphone companies are affected by high and continuing costs of research and development due to quickly evolving technologies. Smartphone companies are often reliant upon the relationships with third-parties, which can be unpredictable. Additionally, the Smartphone industry is in the early stages of development and can be extremely volatile.</p> <p>NON-U.S. SECURITIES AND EMERGING MARKETS RISK. The Fund invests in securities of non-U.S. issuers, including non-U.S. dollar-denominated securities traded outside of the United States and U.S. dollar-denominated securities of non-U.S. issuers traded in the United States. 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. These risks may be heightened for securities of companies located in, or with significant operations in, emerging market countries.</p> <p>DEPOSITARY RECEIPTS RISK. Depositary receipts may be less liquid than the underlying shares in their primary trading market. Any distributions paid to the holders of depositary receipts are usually subject to a fee charged by the depositary. Holders of depositary receipts may have limited voting rights, and investment restrictions in certain countries may adversely impact the value of depositary receipts because such restrictions may limit the ability to convert equity shares into depositary receipts and vice versa. Such restrictions may cause equity shares of the underlying issuer to trade at a discount or premium to the market price of the depositary receipts.</p> <p>CURRENCY RISK. Because the Fund's NAV is determined on the basis of U.S. dollars and the Fund invests in foreign securities, 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 the Fund's holdings goes up.</p>falsefalsefalseus-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 false0Risk Narrative [Text Block]46false 2rr_BarChartAndPerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>ANNUAL TOTAL RETURN</p>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b false0Bar Chart and Performance Table [Heading]47false 2rr_PerformanceNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The bar chart and table below illustrate the annual calendar year return 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, 2012. 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>falsefalsefalseus-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 false0Performance Narrative [Text Block]48false 2rr_BarChartHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>FIRST TRUST NASDAQ CEA SMARTPHONE INDEX FUND--TOTAL RETURN</p>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b false0Bar Chart [Heading]49false 2rr_BarChartTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/BarChartData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalseBarChart2.jpg<div style="display: none">~ http://xbrl.sec.gov/rr/role/BarChartData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000030172Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/BarChartData020050 - Schedule - Annual Total Returnstruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ CEA Smartphone Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000030172Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ CEA Smartphone Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000092838Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ CEA Smartphone Index FundFirst Trust NASDAQ CEA Smartphone Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*6false6false 2rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.19210.1921falsefalsefalse2truetruefalse0.07440.0744falsefalsefalse3truetruefalse0.19690.1969falsefalsefalsexbrli: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 false0Annual Return 2012 2rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalsexbrli: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 false0Annual Return 2012 0rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.07440.0744falsefalsefalsexbrli: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 false0Annual Return 2012falseAnnual Total Returns UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet11031408ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No definition available.false0Bar Chart [Table]50false 2rr_BarChartClosingTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>During the year ended December 31, 2012, the Fund's highest and lowest calendar quarter returns were 15.83% and -17.69%, respectively, for the quarters ended March 31, 2012 and June 30, 2012. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.</p>falsefalsefalseus-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 false0Bar Chart Closing [Text Block]51false 2rr_PerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2012</p>falsefalsefalsexbrli:stringItemTypestringThis item represents Average Anuual Total Returns. 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Index Fund MSCI World Index6falseRowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ CEA Smartphone Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000030172Memberdei_LegalEntityAxisexplicitMembertruefalse[ShareClassDomain]rr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseMSCI All Country World Information Technology Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_MSCIACWorldInfoTechIndexMemberrr_PerformanceMeasureAxisexplicitMemberFirst Trust NASDAQ CEA Smartphone Index Fund[ShareClassDomain]MSCI All Country World Information Technology IndexRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 0truefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.15320.1532falsefalsefalse2truetruetrue0.01810.0181falsefalsefalse3falsetruefalse002011-02-17falsefalsetruenanafalse0First Trust NASDAQ CEA Smartphone Index Fund MSCI All Country World Information Technology IndexfalseAverage Annual Total Returns UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet36121536051ColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000030172MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No definition available.false0Performance [Table]53false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00First Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Fundfalsefalsefalse3false truefalseAsOf2013-07-22_S000026919Memberhttp://www.sec.gov/CIK0001364608duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFLMFONEGRID_S000026919Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000026919Memberdei_LegalEntityAxisexplicitMembernanafalse0First Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Fund54false 2rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>SUMMARY INFORMATION</p>falsefalsefalsexbrli: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 false0Risk/Return [Heading]55false 2rr_ObjectiveHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>INVESTMENT OBJECTIVE</p>falsefalsefalsexbrli: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 false0Objective [Heading]56false 2rr_ObjectivePrimaryTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The 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").</p>falsefalsefalseus-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 false0Objective, Primary [Text Block]57false 2rr_ExpenseHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>FEES AND EXPENSES OF THE FUND</p>falsefalsefalsexbrli: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 false0Expense [Heading]58false 2rr_ExpenseNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The 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.</p>falsefalsefalseus-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 false0Expense Narrative [Text Block]59false 2rr_ShareholderFeesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>SHAREHOLDER FEES (fees paid directly from your investment)</p>falsefalsefalsexbrli: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 false0Shareholder Fees Caption [Text]60false 2rr_ShareholderFeesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/ShareholderFeesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/ShareholderFeesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/ShareholderFeesData020010 - Schedule - Shareholder Feestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000026919Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000081044Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*3false 2rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) 0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue00falsefalsefalserr: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 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)falseShareholder Fees UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet11001105ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No definition available.false0Shareholder Fees [Table]61false 2rr_OperatingExpensesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>ANNUAL FUND OPERATING EXPENSES (Expenses that you pay each year as a percentage of the value of your investment)</p>falsefalsefalsexbrli: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 false0Operating Expenses Caption [Text]62false 2rr_AnnualFundOperatingExpensesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/OperatingExpensesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/OperatingExpensesData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/OperatingExpensesData020020 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000026919Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000081044Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*3false 2rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Management Fees 0rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00400.0040falsefalsefalserr: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 false0Management Fees2falseRowprimaryElement*4false 2rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Distribution and Service (12b-1) Fees 0rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse[1]1truetruetrue0.00000.0000falsefalsefalserr: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 false0Distribution and Service (12b-1) Fees3falseRowprimaryElement*5false 2rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Other Expenses 0rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00390.0039falsefalsefalserr: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 false0Other Expenses4falseRowprimaryElement*6false 2rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Total Annual Fund Operating Expenses 0rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00790.0079falsefalsefalserr: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 false0Total Annual Fund Operating Expenses5falseRowprimaryElement*7false 2rr_FeeWaiverOrReimbursementOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Fee Waiver and Expense Reimbursement 0rr_FeeWaiverOrReimbursementOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse[2]1truetruetrue-0.0009-0.0009falsefalsefalserr: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 false0Fee Waiver and Expense Reimbursement6falseRowprimaryElement*8false 2rr_NetExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr: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 false0Total Net Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement 0rr_NetExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00700.0070falsefalsefalserr: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 false0Total Net Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement1Although the Fund has adopted a 12b-1 plan that permits it to pay up to 0.25% per annum, it will not pay 12b-1 fees at any time before January 31, 2014.2First 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 0.70% of its average daily net assets per year at least until January 31, 2014. Expenses borne by First Trust are subject to reimbursement by the Fund for 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 31, 2014 upon 60 days' written notice.falseAnnual Fund Operating Expenses UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet160516010ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No definition available.false0Annual Fund Operating Expenses [Table]63false 2rr_ExpenseExampleHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>EXAMPLE</p>falsefalsefalsexbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions false0Expense Example [Heading]64false 2rr_ExpenseExampleNoRedemptionNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<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 annual operating expenses remain at current levels until January 31, 2014. 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, 2014. 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 31, 2014. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</p>falsefalsefalseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExampleNoRedemption.No definition available.false0Expense Example, No Redemption Narrative [Text Block]65false 2rr_ExpenseExampleNoRedemptionTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display: none">~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>truehttp://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption020040 - Schedule - Expense Example, No Redemption {Transposed}truefalsefalse1falseColumnprimaryElement*3false 2rr_ExpenseExampleNoRedemptionYear01rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example false21 Year USDfalsefalse$2falseColumnprimaryElement*4false 2rr_ExpenseExampleNoRedemptionYear03rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalserr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example false23 Years USDfalsefalse$3falseColumnprimaryElement*5false 2rr_ExpenseExampleNoRedemptionYear05rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions false25 Years USDfalsefalse$4falseColumnprimaryElement*6false 2rr_ExpenseExampleNoRedemptionYear10rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabelrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions false210 Years USDfalsefalse$1falseRowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000026919Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000081044Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170 0truefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue7272falsefalsefalse2truefalsetrue285285falsefalsefalse3truefalsetrue529529falsefalsefalse4truefalsetrue12291229falsefalsefalsenanafalse0First Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundfalseExpense Example, No Redemption (USD $)UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet413041020ColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExampleNoRedemption.No definition available.false0Expense Example, No Redemption [Table]66false 2rr_PortfolioTurnoverHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PORTFOLIO TURNOVER</p>falsefalsefalsexbrli: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 false0Portfolio Turnover [Heading]67false 2rr_PortfolioTurnoverTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when 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 most recent fiscal year, the Fund's portfolio turnover rate was 46% of the average value of its portfolio.</p>falsefalsefalseus-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 false0Portfolio Turnover [Text Block]68false 2rr_StrategyHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PRINCIPAL INVESTMENT STRATEGIES</p>falsefalsefalsexbrli: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 false0Strategy [Heading]69false 2rr_StrategyNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The Fund will normally invest at least 90% of its net assets (plus the amount of any borrowings for investment purposes) 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 The 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> <p>The Fund intends to invest entirely in securities included in the Index; however, there may also be instances in which the Fund may be underweighted or overweighted in certain securities in the Index, not invest in certain securities included in the Index, purchase securities not in the Index that are appropriate to substitute for certain securities in the Index or utilize various combinations of the above techniques in seeking to track the Index.</p>falsefalsefalseus-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 false0Strategy Narrative [Text Block]70false 2rr_RiskHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>PRINCIPAL RISKS</p>falsefalsefalsexbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b false0Risk [Heading]71false 2rr_RiskNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<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.</p> <p>SMALLER COMPANY RISK. The Fund invests in small and mid capitalization companies. Such companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than larger, more established companies as a result of several factors, including limited trading volumes, products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than larger, more established companies.</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. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly concentrated in certain issuers.</p> <p>INDUSTRIALS SECTOR RISK. The Fund invests in the securities of companies in the industrials sector. Many companies in this sector convert unfinished goods into finished durables used to manufacture other goods or provide services. Some industries included in this sector are electrical equipment and components, industrial products, manufactured housing and telecommunications equipment. General risks of these companies include the general state of the economy, intense competition, consolidation, domestic and international politics, excess capacity and consumer demand and spending trends. In addition, they may also be significantly affected by overall capital spending levels, economic cycles, technical obsolescence, delays in modernization, labor relations, government regulations and e-commerce initiatives.</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>DEPOSITARY RECEIPTS RISK. Depositary receipts may be less liquid than the underlying shares in their primary trading market. Any distributions paid to the holders of depositary receipts are usually subject to a fee charged by the depositary. Holders of depositary receipts may have limited voting rights, and investment restrictions in certain countries may adversely impact the value of depositary receipts because such restrictions may limit the ability to convert equity shares into depositary receipts and vice versa. Such restrictions may cause equity shares of the underlying issuer to trade at a discount or premium to the market price of the depositary receipts.</p> <p>CURRENCY RISK. Because the Fund's NAV is determined on the basis of U.S. dollars and the Fund invests in foreign securities, 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>falsefalsefalseus-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 false0Risk Narrative [Text Block]72false 2rr_BarChartAndPerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>ANNUAL TOTAL RETURN</p>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b false0Bar Chart and Performance Table [Heading]73false 2rr_PerformanceNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>The bar chart and table below illustrate the annual calendar year returns of the Fund based on NAV for the past three years as well as the average annual Fund and Index returns for the one year and since inception periods ended December 31, 2012. 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>falsefalsefalseus-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 false0Performance Narrative [Text Block]74false 2rr_BarChartHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>FIRST TRUST NASDAQ(R) CLEAN EDGE(R) SMART GRID INFRASTRUCTURE INDEX FUND-- TOTAL RETURNS</p>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b false0Bar Chart [Heading]75false 2rr_BarChartTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display: none">~ http://xbrl.sec.gov/rr/role/BarChartData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalseBarChart3.jpg<div style="display: none">~ http://xbrl.sec.gov/rr/role/BarChartData column period compact * column dei_LegalEntityAxis compact FLMFONEGRID_S000026919Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://xbrl.sec.gov/rr/role/BarChartData020050 - Schedule - Annual Total Returnstruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2013-07-22T00:00:002013-07-22T00:00:00falsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_S000026919Memberdei_LegalEntityAxisexplicitMemberfalsefalseFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index Fundrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldiFLMFONEGRID_C000081044Memberrr_ProspectusShareClassAxisexplicitMemberFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundFirst Trust NASDAQ(R) Clean Edge(R) Smart Grid Infrastructure Index FundRatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2013-07-22T00:00:002013-07-22T00:00:00$1falseRowprimaryElement*4false4false 2rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.18230.1823falsefalsefalse2falsetruefalse00falsefalsefalse3truetruefalse-0.0020-0.0020falsefalsefalsexbrli: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. 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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. 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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 false0Annual Return 2012falseAnnual Total Returns UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet13031408ColumnperiodPeriod*Columndei_LegalEntityAxisAxisFLMFONEGRID_S000026919MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falseus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No definition available.false0Bar Chart [Table]76false 2rr_BarChartClosingTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p>During the three-year period ended December 31, 2012, the Fund's highest and lowest calendar quarter returns were 13.59% and -26.52%, respectively, for the quarters ended March 31, 2012 and September 30, 2011. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.</p>falsefalsefalseus-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. 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