Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	First Trust Series Fund
Prospectus Date	rr_ProspectusDate	May 01, 2025
First Trust WCM Focused Global Growth Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<span style="font-family:Arial;font-size:12.60pt;font-weight:bold;">First Trust WCM Focused Global Growth Fund (WFGGX)</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 WCM Focused Global Growth Fund (the "Fund") seeks to provide long-term capital appreciation.
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	This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. Investors purchasing Institutional Class shares as “clean shares” may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the table below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other First Trust Advisors L.P. mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial advisor and in “Share Classes” on page 20 of this prospectus, “Investment in Fund Shares” on page 21 of this prospectus and “Purchase and Redemption of Fund Shares” on page 29 of the Fund’s statement of additional information (“SAI”).
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="color:#000000;font-family:Arial;font-size:8.10pt;font-style:italic;"> October 2, 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 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. As a result of a reorganization, described in greater detail below, the Fund has assumed the performance of WCM Focused Global Growth Fund (the “Predecessor Fund”), an open-end investment management company. During the most recent fiscal year, the Fund’s portfolio turnover rate was 43% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	43.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	<span style="font-family:Arial;font-size:9.00pt;">You may qualify for sales charge discounts if you and your family </span><span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">invest, or agree to invest in the future, at least </span><span style="font-family:Arial;font-size:9.00pt;">$50,000</span><span style="font-family:Arial;font-size:9.00pt;"> in the Fund or in other First Trust Advisors L.P. mutual funds.</span>
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	<span style="color:#000000;font-family:Arial;font-size:8.10pt;font-style:italic;">“Other Expenses” is an estimate based on the expenses the Fund expects to incur for the current fiscal year.</span>
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 (excluding interest expense, taxes, acquired fund fees and expenses, fees incurred in acquiring and disposing of portfolio securities, and extraordinary expenses) remain at current levels through October 2, 2026. Although your actual costs may be higher or lower, based on these assumptions your costs 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	Under normal market conditions, the Fund seeks to achieve its investment objective by investing in the equity securities of companies located throughout the world, including the United States. Such equity securities may include common stock and depositary receipts (including American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”), Canadian Depositary Receipts (“CDRs”) and Global Depositary Receipts (“GDRs”)). The Fund may also invest in securities denominated in non-U.S. currencies. Under normal market conditions, the Fund invests at least 40% of its net assets in companies organized, headquartered or doing a substantial amount of business outside the United States, including emerging and frontier market countries. Emerging and frontier countries or markets are those countries or markets with low- to middle-income economies as classified by the World Bank or included in any of the Morgan Stanley Capital International (MSCI) emerging markets or frontier markets indices. The Fund’s sub-advisor, WCM Investment Management, LLC (the “Sub-Advisor”), considers a company to be located in a country if the company has been organized under the laws of, has its principal offices in, or has its securities principally traded in, the country, or if the company derives at least 50% of its revenues or net profits from, or has at least 50% of its assets or production capacities in, the country. The Sub-Advisor considers a company that has at least 50% of its assets, or derives at least 50% of its revenues from business, outside the United States as doing a substantial amount of business outside the United States. The Sub-Advisor uses a bottom-up approach that seeks to identify companies with attractive fundamentals, such as long-term historical growth in revenue and earnings, and/or a strong probability for superior future growth. The Sub-Advisor’s investment process seeks companies that are industry leaders with strengthening competitive advantages; corporate cultures emphasizing strong, quality and experienced management; low or no debt; and attractive relative valuations. The Sub-Advisor also considers other factors including political risk, monetary policy risk and regulatory risk in selecting securities. Although the Fund may invest in the securities of companies of any size, it generally invests in the securities of established multinational companies. The Fund generally invests in securities of companies located in different regions and in at least three different countries. However, from time to time, the Fund may have a significant portion of its assets invested in the securities of companies in one or a few countries or regions. As of March 31, 2025, the Fund had significant investments in financial companies, information technology companies and European issuers, although this may change from time to time. Over time, the Fund may have significant investments in a jurisdiction or investment sector that it may not have had as of March 31, 2025. 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. The Fund will not invest 25% or more of the value of its total assets in securities of issuers in any one industry or group of industries.
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, information technology companies and European issuers, 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="font-family:Arial;font-size:9.00pt;margin-left:0%;">You could lose money by investing in the Fund.</span><span style="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="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="font-family:Arial;font-size:9.00pt;">There can be no assurance that </span><span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">the Fund’s investment objective will be achieved.</span><span style="font-family:Arial;font-size:9.00pt;"> The order of the below risk factors does not indicate the significance of any 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 shareholders of the Predecessor Fund approved an Agreement and Plan of Reorganization (the “Plan”) by and between the Predecessor Fund and the Trust, on behalf the Fund, pursuant to which the Predecessor Fund would (i) transfer all of its assets to the Fund in exchange solely for newly issued shares of the Fund and the Fund’s assumption of all of the liabilities of the Predecessor Fund, and (ii) immediately distribute such newly issued shares of the Fund to shareholders of the Predecessor Fund (the “Reorganization”). As a result of the Reorganization, the Fund has assumed the performance history of the Predecessor Fund. The bar chart and table below provide some indication of the risks of investing in the Predecessor Fund by showing you how the performance of the Predecessor Fund has varied from year to year until the date of the Reorganization on October 7, 2024. While the Predecessor Fund and Fund have investment policies and practices that are substantially similar, the Predecessor Fund’s past performance is not necessarily indicative of how the Fund will perform in the future. Accordingly, any Fund performance and historical returns shown below that incorporate Predecessor Fund performance prior to October 7, 2024 is not necessarily indicative of the performance that the Fund would have generated.The bar chart and table below illustrate the calendar year returns of the Fund’s Institutional Class shares (having assumed the performance of the Predecessor 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 Institutional Class shares’ average annual total returns compared to those of a broad-based market index. 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 calendar year returns of the Fund’s Institutional Class shares (having assumed the performance of the Predecessor Fund) based on net asset value as well as the average annual Fund 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 (before and after taxes) 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 WCM Focused Global Growth Fund</span><span style="font-family:Arial;font-size:9.90pt;font-weight:bold;margin-left:2.75pt;">—Institutional Class 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 Quarter24.91%June 30, 2020Worst Quarter-18.11%June 30, 2022
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 Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">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.</span>
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	<span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">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 </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">(</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;">IRAs</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">) or employee-sponsored retirement plans.</span>
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	<span style="font-family:Arial;font-size:9.00pt;">Returns after taxes on distributions reflect the taxed return on the payment of dividends </span><span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">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 </span><span style="font-family:Arial;font-size:9.00pt;">an index do not include expenses, which are deducted from Fund returns, or taxes.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.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 an index do not include expenses, which are deducted from Fund returns, or taxes.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.
First Trust WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | Currency Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	CURRENCY RISK. Changes in currency exchange rates affect the value of investments denominated in a foreign currency, and therefore the value of such investments in the Fund’s portfolio. The Fund’s net asset value could decline if a currency to which the Fund has exposure depreciates against the U.S. dollar or if there are delays or limits on repatriation of such currency. Currency exchange rates can be very volatile and can change quickly and unpredictably. As a result, the value of an investment in the Fund may change quickly and without warning.
First Trust WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | Depositary Receipts Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	DEPOSITARY RECEIPTS RISK. Depositary receipts represent equity interests in a foreign company that trade on a local stock exchange. 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 the equity shares into depositary receipts and vice versa. Such restrictions may cause the equity shares of the underlying issuer to trade at a discount or premium to the market price of the depositary receipts.
First Trust WCM Focused Global Growth Fund | Emerging Markets Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	EMERGING MARKETS RISK. Investments in securities issued by governments and companies operating in emerging market countries involve additional risks relating to political, economic, or regulatory conditions not associated with investments in securities and instruments issued by U.S. companies or by companies operating in other developed market countries. Investments in emerging markets securities are generally considered speculative in nature and are subject to the following heightened risks: smaller market capitalization of securities markets which may suffer periods of relative illiquidity; market manipulation; significant price volatility; restrictions on foreign investment; possible repatriation of investment income and capital; rapid inflation; and currency convertibility issues. Emerging market countries also often have less uniformity in accounting, auditing and reporting requirements, unsettled securities laws, unreliable securities valuation and greater risk associated with custody of securities. Financial and other reporting by companies and government entities also may be less reliable in emerging market countries. Shareholder claims that are available in the U.S., as well as regulatory oversight and authority that is common in the U.S., including for claims based on fraud, may be difficult or impossible for shareholders of securities in emerging market countries or for U.S. authorities to pursue. Furthermore, investors may be required to register the proceeds of sales and future economic or political crises could lead to price controls, forced mergers, expropriation or confiscatory taxation, seizure, nationalization or creation of government monopolies.
First Trust WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | Europe Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	EUROPE RISK. The Fund is subject to certain risks specifically associated with investments in the securities of European issuers. Political or economic disruptions in European countries, even in countries in which the Fund is not invested, may adversely affect security values and thus the Fund’s holdings. A significant number of countries in Europe are member states in the European Union (the “EU”), and the member states no longer control their own monetary policies by directing independent interest rates for their currencies. In these member states, the authority to direct monetary policies, including money supply and official interest rates for the Euro, is exercised by the European Central Bank. In a 2016 referendum, the United Kingdom elected to withdraw from the EU (“Brexit”). After years of negotiations between the United Kingdom and the EU, a withdrawal agreement was reached whereby the United Kingdom formally left the EU. As the second largest economy among EU members, the implications of the United Kingdom’s withdrawal are difficult to gauge and cannot be fully known. Its departure may negatively impact the EU and Europe as a whole by causing volatility within the EU, triggering prolonged economic downturns in certain European countries or sparking additional member states to contemplate departing the EU (thereby perpetuating political instability in the region).
First Trust WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | Frontier Markets Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	FRONTIER MARKETS RISK. Frontier market countries generally have smaller economies and even less developed capital markets than traditional emerging markets, and, as a result, the risks of investing in emerging market countries are magnified in frontier market countries. The magnification of risks is the result of potential for extreme price volatility and illiquidity in frontier markets; government ownership or control of parts of private sector and of certain companies; trade barriers, exchange controls, managed adjustments in relative currency values and other protectionist measures imposed or negotiated by the countries with which frontier market countries trade; and the relatively new and unsettled securities laws in many frontier market countries.
First Trust WCM Focused Global Growth Fund | Growth Stocks Investment Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	GROWTH STOCKS INVESTMENT RISK. Stocks exhibiting growth characteristics tend to be more volatile than certain other types of stocks and their prices usually fluctuate more dramatically than the overall stock market. A stock with growth characteristics can have sharp price declines due to decreases in current or expected earnings and may lack dividend payments that can help cushion its share price during declining markets.
First Trust WCM Focused Global Growth Fund | Information Technology Companies Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	INFORMATION TECHNOLOGY COMPANIES RISK. The Fund invests significantly in information technology companies. Information technology companies produce and provide hardware, software and information technology systems and services. These companies may be adversely affected by 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. In addition, information technology companies are particularly vulnerable to federal, state and local government regulation, and competition and consolidation, both domestically and internationally, including competition from foreign competitors with lower production costs. Information technology companies also heavily rely on intellectual property rights and may be adversely affected by the loss or impairment of those rights.
First Trust WCM Focused Global Growth Fund | International Closed Market Trading Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	INTERNATIONAL CLOSED MARKET TRADING RISK. Because securities held by the Fund trade on non-U.S. exchanges that are closed when the Fund’s shares are available for purchase and redemption, there are likely to be deviations between the current price of an underlying security and the last quoted price for the underlying security (i.e., the Fund’s quote from the closed foreign market) used for purposes of calculating the Fund's net asset value. In addition, shareholders may not be able to purchase and sell shares of the Fund on days when the net asset value of the Fund could be significantly affected by events in the relevant foreign markets.
First Trust WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | 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. Certain investments held by the Fund that trade on non-U.S. exchanges may be further subject to liquidity risk due to foreign market closures or unexpected impediments to trading in local markets. 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 WCM Focused Global Growth Fund | 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 Fund's portfolio managers (listed below) 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 WCM Focused Global Growth Fund | 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.
First Trust WCM Focused Global Growth Fund | Non US Securities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	NON-U.S. SECURITIES RISK. Non-U.S. 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, capital controls, lack of liquidity, currency exchange rates, excessive taxation, government seizure of assets, the imposition of sanctions by foreign governments, different legal or accounting standards, and less government supervision and regulation of securities exchanges in foreign countries.
First Trust WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | 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 WCM Focused Global Growth Fund | Valuation Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	VALUATION RISK. The Fund may hold securities or other assets that may be valued on the basis of factors other than market quotations. This may occur because the asset or security does not trade on a centralized exchange, or in times of market turmoil or reduced liquidity. There are multiple methods that can be used to value a portfolio holding when market quotations are not readily available. Fund investments that trade on non-U.S. exchanges that close prior to the close of the NYSE may be fair valued using a systematic fair valuation model. If these foreign investments meet certain criteria in relation to the valuation model, their valuation is systematically adjusted to reflect the impact of movement in the U.S. market after the close of certain foreign markets. The value established for any portfolio holding at a point in time might differ from what would be produced using a different methodology or if it had been priced using market quotations. In addition, there is no assurance that the Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that the Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time. The Fund’s ability to value investments may be impacted by technological issues or errors by pricing services or other third-party service providers.
First Trust WCM Focused Global Growth Fund | Investor Class
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.85%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.25%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.35%
Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[2]
Total Annual Fund Operating Expenses After Fee Waivers and Expense Reimbursements	rr_NetExpensesOverAssets	1.30%
1 Year[ctag:span_t-rule1]	rr_ExpenseExampleYear01	$ 132
3 Years[ctag:span_t-rule1]	rr_ExpenseExampleYear03	412
5 Years[ctag:span_t-rule1]	rr_ExpenseExampleYear05	713
10 Years	rr_ExpenseExampleYear10	1,568
1 Year[ctag:span_t-rule1]	rr_ExpenseExampleNoRedemptionYear01	132
3 Years[ctag:span_t-rule1]	rr_ExpenseExampleNoRedemptionYear03	412
5 Years[ctag:span_t-rule1]	rr_ExpenseExampleNoRedemptionYear05	713
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,568
2015	rr_AnnualReturn2015	11.25%
2016	rr_AnnualReturn2016	3.79%
2017	rr_AnnualReturn2017	27.52%
2018	rr_AnnualReturn2018	(3.16%)
2019	rr_AnnualReturn2019	33.75%
2020	rr_AnnualReturn2020	39.54%
2021	rr_AnnualReturn2021	14.83%
2022	rr_AnnualReturn2022	(30.57%)
2023	rr_AnnualReturn2023	26.45%
2024	rr_AnnualReturn2024	31.03%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	<span style="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	24.91%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	<span style="font-family:Arial;font-size:9.00pt;margin-left:0.0pt;">Worst Quarter</span>
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2022
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.11%)
First Trust WCM Focused Global Growth Fund | Institutional Class
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.85%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets
Other Expenses	rr_OtherExpensesOverAssets	0.23%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.08%
Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[2]
Total Annual Fund Operating Expenses After Fee Waivers and Expense Reimbursements	rr_NetExpensesOverAssets	1.03%
1 Year[ctag:span_t-rule1]	rr_ExpenseExampleYear01	$ 105
3 Years[ctag:span_t-rule1]	rr_ExpenseExampleYear03	328
5 Years[ctag:span_t-rule1]	rr_ExpenseExampleYear05	569
10 Years	rr_ExpenseExampleYear10	1,259
1 Year[ctag:span_t-rule1]	rr_ExpenseExampleNoRedemptionYear01	105
3 Years[ctag:span_t-rule1]	rr_ExpenseExampleNoRedemptionYear03	328
5 Years[ctag:span_t-rule1]	rr_ExpenseExampleNoRedemptionYear05	569
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,259
First Trust WCM Focused Global Growth Fund | before tax | Investor Class
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	30.67%
5 Years	rr_AverageAnnualReturnYear05	12.72%
10 Years	rr_AverageAnnualReturnYear10	13.13%
Since Inception	rr_AverageAnnualReturnSinceInception	12.82%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 2013
First Trust WCM Focused Global Growth Fund | before tax | Institutional Class
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	31.03%
5 Years	rr_AverageAnnualReturnYear05	13.01%
10 Years	rr_AverageAnnualReturnYear10	13.40%
Since Inception	rr_AverageAnnualReturnSinceInception	13.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 2013
First Trust WCM Focused Global Growth Fund | After tax on distributions | Institutional Class
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	29.50%
5 Years	rr_AverageAnnualReturnYear05	11.85%
10 Years	rr_AverageAnnualReturnYear10	12.21%
Since Inception	rr_AverageAnnualReturnSinceInception	12.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 2013
First Trust WCM Focused Global Growth Fund | After tax on distributions and sale of fund shares | Institutional Class
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	19.32%
5 Years	rr_AverageAnnualReturnYear05	10.24%
10 Years	rr_AverageAnnualReturnYear10	10.80%
Since Inception	rr_AverageAnnualReturnSinceInception	10.67%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 2013
First Trust WCM Focused Global Growth Fund | MSCI ACWI Index (reflects no deduction for fees, expenses or taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	17.49%
5 Years	rr_AverageAnnualReturnYear05	10.06%
10 Years	rr_AverageAnnualReturnYear10	9.23%
Since Inception	rr_AverageAnnualReturnSinceInception	9.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 2013

[1] “Other Expenses” is an estimate based on the expenses the Fund expects to incur for the current fiscal year.

[2] The Fund’s investment advisor has agreed to waive fees and reimburse expenses through October 2, 2026 so that Total Annual Fund Operating Expenses (excluding taxes, interest, all brokerage commissions, other normal charges incident to the purchase and sale of portfolio securities, distribution and service fees payable pursuant to a Rule 12b-1 plan, if any, and extraordinary expenses) do not exceed 1.30% of the average daily net assets of Investor Class Shares, and 1.05% of the average daily net assets of Institutional Class shares shares. Fees waived or expenses borne by the Fund’s investment advisor and sub-advisor are subject to reimbursement by the Fund for up to three years from the date the fee was waived 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 (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. Expense limitations may be terminated or modified prior to their expiration only with the approval of the Board of Trustees of the First Trust Series Fund.