v3.25.1
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Risk Return Abstract rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName First Trust Variable Insurance Trust
Prospectus Date rr_ProspectusDate May 01, 2025
First Trust Dow Jones Dividend and Income Allocation Portfolio  
Risk Return Abstract rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading <span style="color:#000000;font-family:Arial;font-size:12.60pt;font-weight:bold;">First Trust/Dow Jones Dividend & Income Allocation Portfolio</span>
Objective [Heading] rr_ObjectiveHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Investment Objective</span>
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The First Trust/Dow Jones Dividend & Income Allocation Portfolio (the "Fund") seeks to provide total return by allocating among dividend-paying stocks and investment grade bonds.
Expense [Heading] rr_ExpenseHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Fees and Expenses of the Fund</span>
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. The Total Annual Fund Operating Expenses reflected below do not include contract level fees of the variable annuity or variable life insurance contracts offered by a Participating Insurance Company (each a “Contract”). If such fees were included, the Total Annual Fund Operating Expenses would be higher. More information about eligibility requirements for Class I is available from your Participating Insurance Company.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption <span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;">Shareholder Fees</span> <br/><span style="color:#000000;font-family:Arial;font-size:9.00pt;">(fees paid directly from your investment)</span>
Operating Expenses Caption [Text] rr_OperatingExpensesCaption <span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;">Annual Fund Operating Expenses</span> <br/><span style="color:#000000;font-family:Arial;font-size:9.00pt;">(expenses that you pay each year as a percentage of the value of your investment)</span>
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination <span style="font-family:Arial;font-size:8.10pt;font-style:italic;">May 1, </span><span style="font-family:Arial;font-size:8.10pt;font-style:italic;">2026</span>
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Portfolio Turnover</span>
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. 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 95% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 95.00%
Expense Example [Heading] rr_ExpenseExampleHeading <span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;font-weight:bold;">Example</span>
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then hold or sell all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s annual operating expenses (before any fee waiver or expense reimbursement) remain at current levels for the time periods indicated. Additionally, the example assumes that the Fund’s investment advisor’s agreement to waive fees and/or pay the Fund’s expenses to the extent necessary to prevent the operating expenses of the Class I shares (excluding interest expense, brokerage commissions and other trading expenses, acquired fund fees and expenses, if any, taxes and extraordinary expenses) from exceeding 1.20% of the Fund’s average daily net assets will be terminated following May 1, 2026. The example does not take into account Contract level fees. If such fees were included, the estimated expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions, your cost would be:
Strategy [Heading] rr_StrategyHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Principal Investment Strategies</span>
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock The Fund seeks to achieve its investment objective by investing, under normal market conditions, approximately 40–60% of its net assets in equity securities and approximately 40–60% of its net assets in fixed income securities at the time of purchase. Under normal market conditions, at the time of purchase at least 80% of the Fund’s net assets (including investment borrowings) will be invested in securities of issuers included in a Dow Jones index. The equity portion of the portfolio will be derived from a quantitative process that seeks to provide total return through investing generally in dividend paying stocks included in the Dow Jones U.S. Total Stock Market IndexSM. The Fund’s investment advisor reserves the right to over-weight, under-weight or exclude certain securities from the portfolio that would otherwise be selected pursuant to the quantitative process in certain instances. The fixed income component seeks to provide income and preserve capital through investing in a diversified investment grade debt portfolio. Investment grade debt securities are those long-term debt securities rated “BBB-” or higher by Standard & Poor’s Financial Services LLC or Fitch, Inc. or “Baa3” or higher by Moody’s Investors Service, Inc., and those short-term debt securities rated “A-3” or higher by Standard & Poor’s Financial Services LLC, “F3” or higher by Fitch, Inc. or “Prime 3” or higher by Moody’s Investors Service, Inc., at the time of purchase. Under normal market conditions, at the time of purchase approximately 80% of the net assets of the Fund allocated to corporate debt will be invested in investment grade debt securities included in the Dow Jones Equal Weight U.S. Issued Corporate Bond Index (the “Bond Index”) and other investment grade debt securities of issuers whose securities are included in the Bond Index; and investment grade debt securities of issuers included in the Dow Jones Composite AverageTM. The Fund may also invest in U.S. government and agency securities, including mortgage-backed securities. The Fund may, at certain times, also hold exchange-traded funds (“ETFs”) that invest in investment grade corporate debt securities and U.S. government bonds in lieu of investing directly in such securities. Corporate debt securities are fixed income securities issued by businesses to finance their operations. Notes, bonds, debentures and commercial paper are the most common types of corporate debt securities, with the primary differences being their maturities and secured or unsecured status. Commercial paper has the shortest term and is usually unsecured. Corporate debt may be rated investment grade or below investment grade and may carry fixed or floating rates of interest. The Fund may also invest in companies with various market capitalizations and when-issued, to-be-announced ("TBA") and delayed delivery securities. As of March 31, 2025, the Fund had significant investments in financial companies, although this may change from time to time. To the extent the Fund invests a significant portion of its assets in a given jurisdiction or investment sector, the Fund may be exposed to the risks associated with that jurisdiction or investment sector.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration <span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">As of March 31, 2025, the Fund had significant investments in financial companies, although this may change from time to time. </span>
Risk [Heading] rr_RiskHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Principal Risks</span>
Risk Caption rr_RiskCaption <span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">You could lose money by investing in the Fund.</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">An investment in the Fund is not a deposit of a bank and is not insured or </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;"> There can be no assurance that </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">the Fund’s investment objective will be achieved. The order of the below risk factors does not indicate the significance of any </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">particular risk factor.</span>
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Annual Total Return</span>
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The bar chart and table below illustrate the annual calendar year returns of the Fund based on net asset value as well as the average annual Fund returns. 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 net asset value compared to those of four broad-based market indices and two blended benchmark indices. The Fund’s performance information is accessible on the Fund’s website at http://www.ftportfolios.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns <span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">The bar chart and table below illustrate the annual calendar year returns of the Fund based on net asset value as well as the average annual Fund returns. 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 net asset value compared to those of four broad-based market indices and two blended benchmark indices. </span>
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex <span style="font-family:Arial;font-size:8.10pt;font-style:italic;">The Blended Benchmark returns are a 50/50 split between the Russell 3000</span><span style="font-family:Arial;font-size:5.5pt;font-style:italic;position:relative;top:-2.75pt;">®</span><span style="font-family:Arial;font-size:8.10pt;font-style:italic;"> Index and the Bloomberg U.S. Corporate Investment-Grade Index returns.</span><span style="font-family:Arial;font-size:8.10pt;font-style:italic;">The Secondary Blended Benchmark return is a 50/50 split between the Dow Jones U.S. Total Stock Market Index</span><span style="font-family:Arial;font-size:5.5pt;font-style:italic;position:relative;top:-2.75pt;">SM</span><span style="font-family:Arial;font-size:8.10pt;font-style:italic;"> and the Dow Jones Equal Weight U.S. Issued Corporate Bond Index</span><span style="font-family:Arial;font-size:5.5pt;font-style:italic;position:relative;top:-2.75pt;">SM</span><span style="font-family:Arial;font-size:8.10pt;font-style:italic;"> returns.</span>
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress <span style="font-family:Arial;font-size:9.00pt;">http://www.ftportfolios.com</span>
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture <span style="color:#000000;font-family:Arial;font-size:9.00pt;">The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.</span>
Bar Chart [Heading] rr_BarChartHeading <span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">First Trust/Dow Jones Dividend & Income Allocation Portfolio</span><span style="font-family:Arial;font-size:9.90pt;font-weight:bold;margin-left:2.75pt;">—Class I Shares</span><br/><span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">Calendar Year Total Returns as of 12/31</span>
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock During the periods shown in the chart above:ReturnPeriod EndedBest Quarter11.64%June 30, 2020Worst Quarter-15.60%March 31, 2020
Performance Table Heading rr_PerformanceTableHeading <span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">Average Annual Total Returns for the Periods Ended December 31, 2024</span>
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Risk Lose Money [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock You could lose money by investing in the Fund.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Risk Not Insured Depository Institution [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock 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.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Call Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CALL RISK. Some debt securities may be redeemed, or “called,” at the option of the issuer before their stated maturity date. In general, an issuer will call its debt securities if they can be refinanced by issuing new debt securities which bear a lower interest rate. The Fund is subject to the possibility that during periods of falling interest rates an issuer will call its high yielding debt securities. The Fund would then be forced to invest the proceeds at lower interest rates, likely resulting in a decline in the Fund’s income.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Credit Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CREDIT RISK. An issuer or other obligated party of a debt security may be unable or unwilling to make dividend, interest and/or principal payments when due. In addition, the value of a debt security may decline because of concerns about the issuer’s ability or unwillingness to make such payments.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Current Market Conditions Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CURRENT MARKET CONDITIONS RISK. Current market conditions risk is the risk that a particular investment, or shares of the Fund in general, may fall in value due to current market conditions. As a means to fight inflation, which remains at elevated levels, the Federal Reserve and certain foreign central banks have raised interest rates; however, the Federal Reserve has recently lowered interest rates and may continue to do so. U.S. regulators have proposed several changes to market and issuer regulations which would directly impact the Fund, and any regulatory changes could adversely impact the Fund’s ability to achieve its investment strategies or make certain investments. Recent and potential future bank failures could result in disruption to the broader banking industry or markets generally and reduce confidence in financial institutions and the economy as a whole, which may also heighten market volatility and reduce liquidity. Additionally, challenges in commercial real estate markets, including rising interest rates, declining valuations and increasing vacancies, could have a broader impact on financial markets. The ongoing adversarial political climate in the United States, as well as political and diplomatic events both domestic and abroad, have and may continue to have an adverse impact the U.S. regulatory landscape, markets and investor behavior, which could have a negative impact on the Fund’s investments and operations. The change in administration resulting from the 2024 United States national elections could result in significant impacts to international trade relations, tax and immigration policies, and other aspects of the national and international political and financial landscape, which could affect, among other things, inflation and the securities markets generally. Other unexpected political, regulatory and diplomatic events within the U.S. and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy. For example, ongoing armed conflicts between Russia and Ukraine in Europe and among Israel, Iran, Hamas and other militant groups in the Middle East, have caused and could continue to cause significant market disruptions and volatility within the markets in Russia, Europe, the Middle East and the United States. The hostilities and sanctions resulting from those hostilities have and could continue to have a significant impact on certain Fund investments as well as Fund performance and liquidity. The economies of the United States and its trading partners, as well as the financial markets generally, may be adversely impacted by trade disputes, including the imposition of tariffs, and other matters. For example, the United States has imposed trade barriers and restrictions on China. In addition, the Chinese government is engaged in a longstanding dispute with Taiwan, continually threatening an invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt invading Taiwan, or if other geopolitical conflicts develop or worsen, economies, markets and individual securities may be adversely affected, and the value of the Fund’s assets may go down. A public health crisis and the ensuing policies enacted by governments and central banks may cause significant volatility and uncertainty in global financial markets, negatively impacting global growth prospects. As the COVID-19 global pandemic illustrated, such events may affect certain geographic regions, countries, sectors and industries more significantly than others. Advancements in technology may also adversely impact markets and the overall performance of the Fund. For instance, the economy may be significantly impacted by the advanced development and increased regulation of artificial intelligence. Additionally, cyber security breaches of both government and non-government entities could have negative impacts on infrastructure and the ability of such entities, including the Fund, to operate properly. These events, and any other future events, may adversely affect the prices and liquidity of the Fund’s portfolio investments and could result in disruptions in the trading markets.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Cyber Security Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CYBER SECURITY RISK. The Fund is susceptible to operational risks through breaches in cyber security. A breach in cyber security refers to both intentional and unintentional events that may cause the Fund to lose proprietary information, suffer data corruption or lose operational capacity. Such events could cause the Fund to incur regulatory penalties, reputational damage, additional compliance costs associated with corrective measures and/or financial loss. Cyber security breaches may involve unauthorized access to the Fund’s digital information systems through “hacking” or malicious software coding but may also result from outside attacks such as denial-of-service attacks through efforts to make network services unavailable to intended users. In addition, cyber security breaches of the issuers of securities in which the Fund invests or the Fund’s third-party service providers, such as its administrator, transfer agent, custodian, or sub-advisor, as applicable, can also subject the Fund to many of the same risks associated with direct cyber security breaches. Although the Fund has established risk management systems designed to reduce the risks associated with cyber security, there is no guarantee that such efforts will succeed, especially because the Fund does not directly control the cyber security systems of issuers or third-party service providers.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Debt Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock DEBT SECURITIES RISK. Investments in debt securities subject the holder to the credit risk of the issuer. Credit risk refers to the possibility that the issuer or other obligor of a security will not be able or willing to make payments of interest and principal when due. Generally, the value of debt securities will change inversely with changes in interest rates. To the extent that interest rates rise, certain underlying obligations may be paid off substantially slower than originally anticipated and the value of those securities may fall sharply. During periods of falling interest rates, the income received by the Fund may decline. If the principal on a debt security is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. Debt securities generally do not trade on a securities exchange making them generally less liquid and more difficult to value than common stock.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Dividends Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock DIVIDENDS RISK. The Fund’s investment in dividend-paying securities could cause the Fund to underperform similar funds that invest without consideration of an issuer’s track record of paying dividends. Companies that issue dividend-paying securities are not required to continue to pay dividends on such securities. Therefore, there is the possibility that such companies could reduce or eliminate the payment of dividends in the future, which could negatively affect the Fund’s performance.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Equity Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock EQUITY SECURITIES RISK. The value of the Fund's shares will fluctuate with changes in the value of the equity securities in which it invests. Equity securities prices fluctuate for several reasons, including changes in investors’ perceptions of the financial condition of an issuer or the general condition of the relevant equity market, such as market volatility, or when political or economic events affecting an issuer occur. Common stock prices may be particularly sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase. Equity securities may decline significantly in price over short or extended periods of time, and such declines may occur in the equity market as a whole, or they may occur in only a particular country, company, industry or sector of the market.
First Trust Dow Jones Dividend and Income Allocation Portfolio | ETF Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock ETF RISK. Under certain market conditions, the Fund may invest in ETFs. The Fund’s investment in shares of ETFs subjects it to the risks of owning the securities underlying the ETF, as well as certain structural risks, including authorized participant concentration risk, market maker risk, premium/discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF’s expenses, subjecting Fund shareholders to duplicative expenses.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Extension Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock EXTENSION RISK. Extension risk is the risk that, when interest rates rise, certain obligations will be paid off by the issuer (or other obligated party) more slowly than anticipated, causing the value of these debt securities to fall. Rising interest rates tend to extend the duration of debt securities, making their market value more sensitive to changes in interest rates. The value of longer-term debt securities generally changes more in response to changes in interest rates than shorter-term debt securities. As a result, in a period of rising interest rates, securities may exhibit additional volatility and may lose value.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Financial Companies Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock FINANCIAL COMPANIES RISK. Financial companies, such as retail and commercial banks, insurance companies and financial services companies, are especially subject to the adverse effects of economic recession, currency exchange rates, extensive government regulation, decreases in the availability of capital, volatile interest rates, portfolio concentrations in geographic markets, industries or products (such as commercial and residential real estate loans), competition from new entrants and blurred distinctions in their fields of business.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Floating Rate Debt Instruments Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock FLOATING RATE DEBT INSTRUMENTS RISK. Investments in floating rate debt instruments are subject to the same risks as investments in other types of debt securities, including credit risk, interest rate risk, liquidity risk and valuation risk. Floating rate debt instruments include debt securities issued by corporate and governmental entities, as well as bank loans, mortgage-backed securities and asset-backed securities. Floating rate debt instruments are structured so that the security’s coupon rate fluctuates based upon the level of a reference rate. Most commonly, the coupon rate of a floating rate debt instrument is set at the level of a widely followed interest rate, plus a fixed spread. As a result, the coupon on floating rate debt instrument will generally decline in a falling interest rate environment, causing the Fund to experience a reduction in the income it receives from the instrument. A floating rate debt instrument’s coupon rate resets periodically according to its terms. Consequently, in a rising interest rate environment, floating rate debt instruments with coupon rates that reset infrequently may lag behind the changes in market interest rates. Floating rate debt instruments may also contain terms that impose a maximum coupon rate the issuer will pay, regardless of the level of the reference rate. To the extent the Fund invests in floating rate loans, such instruments may be subject to legal or contractual restrictions on resale, may trade infrequently, and their value may be impaired when the Fund needs to liquidate such securities. It is possible that the collateral securing a floating rate loan may be insufficient or unavailable to the Fund, and that the Fund’s rights to collateral may be limited by bankruptcy or insolvency laws. Additionally, floating rate loans may not be considered “securities” under federal securities laws, and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws.
First Trust Dow Jones Dividend and Income Allocation Portfolio | High Yield Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock HIGH YIELD SECURITIES RISK. High yield securities, or “junk” bonds, are subject to greater market fluctuations, are less liquid and provide a greater risk of loss than investment grade securities, and therefore, are considered to be highly speculative. In general, high yield securities may have a greater risk of default than other types of securities and could cause income and principal losses for the Fund.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Income Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock INCOME RISK. The Fund’s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Inflation Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock INFLATION RISK. Inflation risk is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the present value of the Fund’s assets and distributions may decline.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Interest Rate Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock INTEREST RATE RISK. Interest rate risk is the risk that the value of the debt securities in the Fund’s portfolio will decline because of rising market interest rates. Interest rate risk is generally lower for shorter term debt securities and higher for longer-term debt securities. The Fund may be subject to a greater risk of rising interest rates than would normally be the case during periods of low interest rates. Duration is a reasonably accurate measure of a debt security’s price sensitivity to changes in interest rates and a common measure of interest rate risk. Duration measures a debt security’s expected life on a present value basis, taking into account the debt security’s yield, interest payments and final maturity. In general, duration represents the expected percentage change in the value of a security for an immediate 1% change in interest rates. For example, the price of a debt security with a three-year duration would be expected to drop by approximately 3% in response to a 1% increase in interest rates. Therefore, prices of debt securities with shorter durations tend to be less sensitive to interest rate changes than debt securities with longer durations. Higher sensitivity to interest rates is generally correlated with higher levels of volatility and, therefore, greater risk. As the value of a debt security changes over time, so will its duration.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Large Capitalization Companies Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock LARGE CAPITALIZATION COMPANIES RISK. Large capitalization companies may grow at a slower rate and be less able to adapt to changing market conditions than smaller capitalization companies. Thus, the return on investment in securities of large capitalization companies may be less than the return on investment in securities of small and/or mid capitalization companies. The performance of large capitalization companies also tends to trail the overall market during different market cycles.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Liquidity Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock LIQUIDITY RISK. The Fund may hold certain investments that may be subject to restrictions on resale, trade over-the-counter or in limited volume, or lack an active trading market. Accordingly, the Fund may not be able to sell or close out of such investments at favorable times or prices (or at all), or at the prices approximating those at which the Fund currently values them. Illiquid securities may trade at a discount from comparable, more liquid investments and may be subject to wide fluctuations in market value.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Management Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock MANAGEMENT RISK. The Fund is subject to management risk because it is an actively managed portfolio. In managing the Fund’s investment portfolio, the portfolio managers will apply investment techniques and risk analyses that may not produce the desired result. There can be no guarantee that the Fund will meet its investment objective.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Market Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock MARKET RISK. Market risk is the risk that a particular investment, or shares of the Fund in general, may fall in value. Securities are subject to market fluctuations caused by real or perceived adverse economic, political, and regulatory factors or market developments, changes in interest rates and perceived trends in securities prices. Shares of the Fund could decline in value or underperform other investments. In addition, local, regional or global events such as war, acts of terrorism, market manipulation, government defaults, government shutdowns, regulatory actions, political changes, diplomatic developments, the imposition of sanctions and other similar measures, spread of infectious diseases or other public health issues, recessions, natural disasters, or other events could have a significant negative impact on the Fund and its investments. Any of such circumstances could have a materially negative impact on the value of the Fund’s shares, the liquidity of an investment, and may result in increased market volatility. During any such events, the Fund’s shares may trade at increased premiums or discounts to their net asset value, the bid/ask spread on the Fund’s shares may widen and the returns on investment may fluctuate.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Mortgage Related Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock MORTGAGE-RELATED SECURITIES RISK. Mortgage-related securities are subject to the same risks as investments in other types of debt securities, including credit risk, interest rate risk, liquidity risk and valuation risk. However, these investments make the Fund more susceptible to adverse economic, political or regulatory events that affect the value of real estate. Mortgage-related securities are also significantly affected by the rate of prepayments and modifications of the mortgage loans underlying those securities, as well as by other factors such as borrower defaults, delinquencies, realized or liquidation losses and other shortfalls. Certain of the mortgage-related securities held by the Fund may not be backed by the full faith and credit of the U.S. government, and such securities will be further subjected to the credit risk of the issuer of the securities. The incidence of borrower defaults or delinquencies may rise significantly during financial downturns and could adversely affect the value of mortgage-related securities held by the Fund. Events such as war, acts of terrorism, spread of infectious diseases or other public health issues, recessions, or other events that result in broad and simultaneous financial hardships for individuals and businesses could have a significant negative impact on the value of mortgage-related securities. Mortgage-related securities are particularly sensitive to prepayment risk and extension risk, given that mortgage loans generally allow borrowers to refinance. In periods of declining interest rates, borrowers may be more apt to prepay their mortgage sooner than expected. This can reduce the returns to the security holder as the amount of interest related to the price may be reduced while the proceeds may have to be reinvested at lower prevailing interest rates. This is prepayment risk. In periods of rising interest rates, borrowers may be less likely to refinance than expected thus extending the cash flows of the security such that there is increased downward price sensitivity to interest rate changes. This is extension risk. As the timing and amount of prepayments cannot be accurately predicted, the timing of changes in the rate of prepayments of the mortgage loans may significantly affect the Fund's actual yield to maturity on any mortgage-related securities. Along with prepayment risk, mortgage-related securities are significantly affected by interest rate risk.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Operational Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock OPERATIONAL RISK. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund’s ability to meet its investment objective. Although the Fund and the Fund's investment advisor seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Prepayment Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock PREPAYMENT RISK. Prepayment risk is the risk that the issuer of a debt security will repay principal prior to the scheduled maturity date. Debt securities allowing prepayment may offer less potential for gains during a period of declining interest rates, as the Fund may be required to reinvest the proceeds of any prepayment at lower interest rates. These factors may cause the value of an investment in the Fund to change.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Significant Exposure Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock SIGNIFICANT EXPOSURE RISK. To the extent that the Fund invests a significant percentage of its assets in a single asset class or the securities of issuers within the same country, state, region, industry or sector, an adverse economic, business or political development may affect the value of the Fund’s investments more than if the Fund were more broadly diversified. A significant exposure makes the Fund more susceptible to any single occurrence and may subject the Fund to greater market risk than a fund that is more broadly diversified.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Smaller Companies Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock SMALLER COMPANIES RISK. Small and/or mid capitalization companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than larger, more established companies as a result of several factors, including limited trading volumes, fewer products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than larger, more established companies.
First Trust Dow Jones Dividend and Income Allocation Portfolio | US Government Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock U.S. GOVERNMENT SECURITIES RISK. U.S. government securities are subject to interest rate risk but generally do not involve the credit risks associated with investments in other types of debt securities. As a result, the yields available from U.S. government securities are generally lower than the yields available from other debt securities. U.S. government securities are guaranteed only as to the timely payment of interest and the payment of principal when held to maturity. While securities issued or guaranteed by U.S. federal government agencies (such as Ginnie Mae) are backed by the full faith and credit of the U.S. Department of the Treasury, securities issued by government sponsored entities (such as Fannie Mae and Freddie Mac) are solely the obligation of the issuer and generally do not carry any guarantee from the U.S. government.
First Trust Dow Jones Dividend and Income Allocation Portfolio | Valuation Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock VALUATION RISK. The sale price the Fund could receive for a security may differ from the Fund’s valuation of the security, particularly for securities that trade in low volume or volatile markets or that are valued using a fair value methodology. Unlike publicly traded securities that trade on national securities exchanges, there is no central place or exchange for trading most debt securities. Debt securities generally trade on an “over-the-counter” market. Due to the lack of centralized information and trading, and variations in lot sizes of certain debt securities, the valuation of debt securities may carry more uncertainty and risk than that of publicly traded securities. Debt securities are commonly valued by third-party pricing services that utilize a range of market-based inputs and assumptions, including readily available market quotations obtained from broker-dealers making markets in such securities, cash flows and transactions for comparable instruments. However, because the available information is less reliable and more subjective, elements of judgment may play a greater role in valuation of debt securities than for other types of securities. Different pricing services may incorporate different assumptions and inputs into their valuation methodologies, potentially resulting in different values for the same securities. As a result, if the Advisor were to change its valuation policies, or if the Fund were to change pricing services, or if a pricing service were to change its valuation methodology, there could be a material impact, either positive or negative, on the Fund’s net asset value. Additionally, pricing services generally price debt securities assuming orderly transactions of an institutional “round lot” size, but some trades may occur in smaller, “odd lot” sizes, often at lower prices than institutional round lot trades. There is no assurance that the Fund will be able to sell a portfolio security at the price established by the pricing service, which could result in a loss to the Fund. In addition, the value of the debt securities in the Fund's portfolio may change on days or during time periods when shareholders will not be able to purchase or sell the Fund's shares. Authorized Participants who purchase or redeem Fund shares on days when the Fund is holding fair-valued securities may receive fewer or more shares, or lower or higher redemption proceeds, than they would have received had the Fund not fair-valued securities or used a different valuation methodology. Net asset value calculation may also be impacted by operational risks arising from factors such as failures in systems and technology.
First Trust Dow Jones Dividend and Income Allocation Portfolio | When Issued TBA And Delayed Delivery Transactions Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock WHEN-ISSUED, TBA AND DELAYED DELIVERY TRANSACTIONS RISK. The Fund may purchase securities on a when-issued, to-be-announced ("TBA"), delayed delivery or forward commitment basis. In such a transaction, the purchase price of the securities is typically fixed at the time of the commitment, but delivery and payment can take place a month or more after the date of the commitment. At the time of delivery of the securities, the value may be more or less than the purchase or sale price. Purchasing securities on a when-issued, TBA, delayed delivery or forward commitment basis may give rise to investment leverage and may increase the Fund’s volatility. Default by, or bankruptcy of, a counterparty to a when-issued, TBA, delayed delivery or forward commitment transaction would expose the Fund to possible losses because of an adverse market action, expenses or delays in connection with the purchase or sale of the pools specified in such transaction.
First Trust Dow Jones Dividend and Income Allocation Portfolio | I  
Risk Return Abstract rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)[ctag:span_t-rule1] rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Management Fees[ctag:span_t-indent1] rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees[ctag:span_t-indent1] rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses[ctag:span_t-indent1-rule] rr_OtherExpensesOverAssets 0.33%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.18%
Fee Waiver and Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none [1]
Total Net Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement[ctag:span_t-indent1-rule3] rr_NetExpensesOverAssets 1.18%
1 Year rr_ExpenseExampleNoRedemptionYear01 $ 120
3 Years rr_ExpenseExampleNoRedemptionYear03 375
5 Years rr_ExpenseExampleNoRedemptionYear05 649
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,432
2015 rr_AnnualReturn2015 0.09%
2016 rr_AnnualReturn2016 11.74%
2017 rr_AnnualReturn2017 13.47%
2018 rr_AnnualReturn2018 (4.92%)
2019 rr_AnnualReturn2019 20.77%
2020 rr_AnnualReturn2020 7.81%
2021 rr_AnnualReturn2021 12.25%
2022 rr_AnnualReturn2022 (12.20%)
2023 rr_AnnualReturn2023 10.51%
2024 rr_AnnualReturn2024 6.01%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel <span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;">Best Quarter</span>
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.64%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel <span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;">Worst Quarter</span>
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (15.60%)
1 Year rr_AverageAnnualReturnYear01 6.01%
5 Years rr_AverageAnnualReturnYear05 4.48%
10 Years rr_AverageAnnualReturnYear10 6.14%
Since Inception rr_AverageAnnualReturnSinceInception 6.97%
Inception Date rr_AverageAnnualReturnInceptionDate May 01, 2012
First Trust Dow Jones Dividend and Income Allocation Portfolio | Blended Benchmark (reflects no deduction for fees, expenses or taxes) | I  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 12.58% [2]
5 Years rr_AverageAnnualReturnYear05 7.13% [2]
10 Years rr_AverageAnnualReturnYear10 7.61% [2]
Since Inception rr_AverageAnnualReturnSinceInception 8.34% [2]
First Trust Dow Jones Dividend and Income Allocation Portfolio | Bloomberg U.S. Corporate Investment-Grade Index (reflects no deduction for fees, expenses or taxes) | I  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.13%
5 Years rr_AverageAnnualReturnYear05 0.30%
10 Years rr_AverageAnnualReturnYear10 2.43%
Since Inception rr_AverageAnnualReturnSinceInception 2.87%
First Trust Dow Jones Dividend and Income Allocation Portfolio | Russell 3000® Index (reflects no deduction for fees, expenses or taxes) | I  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 23.81%
5 Years rr_AverageAnnualReturnYear05 13.86%
10 Years rr_AverageAnnualReturnYear10 12.55%
Since Inception rr_AverageAnnualReturnSinceInception 13.65%
First Trust Dow Jones Dividend and Income Allocation Portfolio | Secondary Blended Benchmark (reflects no deduction for fees, expenses or taxes) | I  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 12.19% [3]
5 Years rr_AverageAnnualReturnYear05 7.03% [3]
10 Years rr_AverageAnnualReturnYear10 7.59% [3]
Since Inception rr_AverageAnnualReturnSinceInception 8.35% [3]
First Trust Dow Jones Dividend and Income Allocation Portfolio | Dow Jones Equal Weight U.S. Issued Corporate Bond Index(SM) (reflects no deduction for fees, expenses or taxes) | I  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 1.34%
5 Years rr_AverageAnnualReturnYear05 0.18%
10 Years rr_AverageAnnualReturnYear10 2.46%
Since Inception rr_AverageAnnualReturnSinceInception 2.94%
First Trust Dow Jones Dividend and Income Allocation Portfolio | Dow Jones U.S. Total Stock Market Index(SM) (reflects no deduction for fees, expenses or taxes) | I  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 23.88%
5 Years rr_AverageAnnualReturnYear05 13.78%
10 Years rr_AverageAnnualReturnYear10 12.48%
Since Inception rr_AverageAnnualReturnSinceInception 13.58%
[1] The Fund’s investment advisor has agreed to waive fees and/or pay the Fund’s expenses to the extent necessary to prevent the operating expenses of the Class I shares (excluding interest expense, brokerage commissions and other trading expenses, acquired fund fees and expenses, if any, taxes and extraordinary expenses) from exceeding 1.20% of the Fund’s average daily net assets at least through May 1, 2026. Expenses borne by the Fund’s investment advisor 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 Class I share expenses (excluding interest expense, brokerage commissions and other trading expenses, acquired fund fees and expenses, if any, taxes and extraordinary expenses) exceeding (i) the applicable expense limitation in place for the most recent fiscal year for which such expense limitation was in place, (ii) the applicable expense limitation in place at the time the fees were waived, or (iii) the current expense limitation. The agreement may be terminated by the Trust on behalf of the Fund at any time and by the Fund’s investment advisor only after May 1, 2026 upon 60 days’ written notice.
[2] The Blended Benchmark returns are a 50/50 split between the Russell 3000® Index and the Bloomberg U.S. Corporate Investment-Grade Index returns.
[3] The Secondary Blended Benchmark return is a 50/50 split between the Dow Jones U.S. Total Stock Market IndexSM and the Dow Jones Equal Weight U.S. Issued Corporate Bond IndexSM returns.