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Risk/Return: rr_RiskReturnAbstract  
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
Because the Fund holds securities with fluctuating market prices, the value of the Fund’s shares will vary as its portfolio securities increase or decrease in value. Therefore, the value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund.
The principal risks affecting the Fund that can cause a decline in value are:
  
•   New Fund Risk: the risk that a new fund’s performance may not represent how the fund is expected to or may perform in the long term. In addition, new funds have limited operating histories for investors to evaluate and new funds may not attract sufficient assets to achieve investment and trading efficiencies. 
•   Debt Securities Risk: the risk that the value of a debt security may increase or decrease as a result of various factors, including changes in interest rates, actual or perceived inability or unwillingness of issuers to make principal or interest payments, market fluctuations and illiquidity in the debt securities market. 
•   Market Risk: the risk that returns from the securities in which the Fund invests may underperform returns from the general securities markets or other types of securities. 
•   Mortgage-Backed Securities Risk: the risk of investing in mortgage-backed securities, including prepayment risk and extension risk. Mortgage-backed securities react differently to changes in interests rates than other bonds, and some mortgage-backed securities are not backed by the full faith and credit of the U.S. government. . 
•   Asset-Backed Securities Risk: the risk of investing in asset-backed securities, including the risk of loss as a result of the impairment of the value of the underlying financial assets, prepayment risk and extension risk. Issuers of asset-backed securities may have limited ability to enforce the security interest in the underlying assets, and credit enhancements provided to support the asset-backed securities, if any, may be inadequate to protect investors in the event of default. 
•   Interest Rate Risk: the risk that debt securities may decline in value because of changes in interest rates. 
•   Credit Risk: the risk that an issuer may default in the payment of principal and/or interest on a security. 
•   Price Volatility Risk: the risk that the value of the Fund’s investment portfolio will change as the prices of its investments go up or down. 
•   Issuer Risk: the risk that the value of a security may decline for reasons directly related to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods or services. 
•   Short Sales Risk: the risk that the use of short sales, which are speculative investments, may cause the Fund to lose money if the value of a security does not go down as the Adviser expects. The risk of loss is theoretically unlimited if the value of the security sold short continues to increase. In addition, the use of short sales may cause the Fund to have higher expenses (especially interest and dividend expenses) than those of other mutual funds that do not engage in short sales. 
•   Liquidity Risk: the risk that lack of a ready market or restrictions on resale may limit the ability of the Fund to sell a security at an advantageous time or price. In addition, 
   
the Fund, by itself or together with other accounts managed by the Adviser, may hold a position in a security that is large relative to the typical trading volume for that security, which can make it difficult for the Fund to dispose of the position at an advantageous time or price. Over recent years, the fixed-income markets have grown more than the ability of dealers to make markets, which can further constrain liquidity and increase the volatility of portfolio valuations. High levels of redemptions in bond funds in response to market conditions could cause greater losses as a result. Regulations such as the Volcker Rule or future regulations may further constrain the ability of market participants to create liquidity, particularly in times of increased market volatility. The liquidity of the Fund’s assets may change over time. 
•   ESG Investing Risk: the risk that the Fund’s ESG strategy may select or exclude securities of certain issuers for non-financial reasons, and that the Fund’s performance will differ from funds that do not utilize an ESG investing strategy. For example, the application of this strategy could affect the Fund’s exposure to certain sectors or types of investments, which could negatively impact the Fund’s performance. ESG investing is qualitative and subjective by nature, and there is no guarantee that the criteria used by the Adviser or any judgment exercised by the Adviser will reflect the opinions of any particular investor. Funds with ESG investment strategies are generally suited for long-term rather than short-term investors. 
•   Below Investment Grade Mortgage-Backed Securities Risk: the Fund’s investments in residential mortgage-backed securities (“RMBS”) and commercial mortgage-backed securities (“CMBS”) that are rated below investment grade generally carry greater liquidity risk than their investment grade counterparts. Historically, the markets for such below investment grade securities, and for below investment grade asset-backed securities in general, have been characterized at times by less liquidity than the market for analogous investment grade securities, particularly during the financial crisis of 2007 and 2008. 
•   Frequent Trading Risk: the risk that frequent trading may lead to increased portfolio turnover and higher transaction costs, which may reduce the Fund’s performance and may cause higher levels of current tax liability to shareholders of the Fund. 
•   Valuation Risk: the risk that the portfolio instruments may be sold at prices different from the values established by the Fund, particularly for investments that trade in low volume, in volatile markets or over the counter or that are fair valued. 
•   Prepayment Risk: the risk that in times of declining interest rates, the Fund’s higher yielding securities may be prepaid and the Fund may have to replace them with securities having a lower yield. 
•   Extension Risk: the risk that in times of rising interest rates, borrowers may pay off their debt obligations more slowly, causing securities considered short- or intermediate-term to become longer-term securities that fluctuate more widely in response to changes in interest rates than shorter-term securities. 
•   U.S. Treasury Obligations Risk: the risk that the value of U.S. Treasury obligations may decline as a result of changes in interest rates, certain political events in the U.S., and strained relations with certain foreign countries. 
•   U.S. Government Securities Risk: the risk that debt securities issued or guaranteed by certain U.S. government agencies, instrumentalities, and sponsored enterprises are not supported by the full faith and credit of the U.S. government, and as a result, investments in their securities or obligations issued by such entities involve credit risk greater than investments in other types of U.S. government securities. 
•   Leverage Risk: the risk that leverage may result from certain transactions, including the use of derivatives and borrowing. This may impair the Fund’s liquidity, cause it to liquidate positions at an unfavorable time, increase its volatility or otherwise cause it not to achieve its intended result. To the extent required by applicable law or regulation, the Fund will reduce leverage risk by either segregating an equal amount of liquid assets or “covering” the transactions that introduce such risk. 
•   Counterparty Risk: the risk that the other party to a contract, such as a derivatives contract, may not fulfill its contractual obligations. 
•   Derivatives Risk: the risk of investing in derivative instruments, which includes liquidity, interest rate, market, credit and management risks as well as risks related to mispricing or improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, reference rate or index, and the Fund could lose more than the principal amount invested. These investments can create investment leverage and may create additional risks that may subject the Fund to greater volatility and less liquidity than investments in more traditional securities. 
•   Swap Agreements Risk: the risk of investing in swaps, which, in addition to risks applicable to derivatives generally, includes: (1) the inability to assign a swap contract 
   
without the consent of the counterparty; (2) potential default of the counterparty to a swap for those not traded through a central counterparty; (3) absence of a liquid secondary market for any particular swap at any time; and (4) possible inability of the Fund to close out a swap transaction at a time that otherwise would be favorable for it to do so. 
•   Futures Contracts Risk: the risk of investing in futures contracts, which includes (1) the imperfect correlation between a futures contract and the change in market value of the underlying instrument held by the Fund; (2) a high degree of leverage because of the low collateral deposits normally involved in futures trading; (3) possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (4) losses caused by unanticipated market movements, which are potentially unlimited; and (5) the inability of the Fund to execute a trade because of the maximum permissible price movements exchanges may impose on futures contracts. 
•   Junk Bond Risk: the risk that junk bonds have a higher degree of default risk and may be less liquid and subject to greater price volatility than investment grade bonds. 
•   Unrated Securities Risk: the risk that unrated securities may be less liquid than comparable rated securities, and the risk that the Adviser may not accurately evaluate the security’s comparative credit rating. 
•   Foreign Investing Risk: the risk that Fund share prices may fluctuate with market conditions, currency exchange rates and the economic and political climates of the foreign countries in which the Fund invests or has exposure. Investments in foreign securities may involve greater risks than investing in U.S. securities due to, among other factors, less publicly available information, less stringent and less uniform accounting, auditing and financial reporting standards, less liquid and more volatile markets, higher transaction and custody costs, additional taxes, less investor protection, delayed or less frequent settlement, political or social instability, civil unrest, acts of terrorism, regional economic volatility, and the imposition of sanctions, confiscations, trade restrictions (including tariffs) and other government restrictions by the United States and/or other governments. 
•   Foreign Currency Risk: the risk that any hedging transactions used by the Fund are not effective in protecting against a decline in the value of foreign currencies relative to the U.S. dollar and affect the Fund’s investments in foreign currencies, in securities that are denominated, trade and/or receive revenues in foreign currencies, or in derivatives that provide exposure to foreign currencies. 
•   Emerging Markets Risk: the risk of investing in emerging market countries, which is substantial due to, among other factors, higher brokerage costs in certain countries; different accounting standards; thinner trading markets as compared to those in developed countries; less publicly available and reliable information about issuers as compared to developed markets; the possibility of currency transfer restrictions; and the risk of expropriation, nationalization or other adverse political, economic or social developments. 
•   Non-U.S. Money Market Securities Risk: the risk of investing in non-U.S. money market securities, which, in addition to risks that are applicable to money market securities generally, such as credit risk and issuer risk, includes currency risk and liquidity risk. 
•   Distressed and Defaulted Securities Risk: the risk that the repayment of defaulted securities and obligations of distressed issuers is subject to significant uncertainties. 
•   Securities Selection Risk: the risk that the securities held by the Fund may underperform those held by other funds investing in the same asset class or included in benchmarks that are representative of the same asset class because of the portfolio managers’ choice of securities. 
•   Portfolio Management Risk: the risk that an investment strategy may fail to produce the intended results. 
•   Public Health Emergency Risk: the risk that pandemics and other public health emergencies, including outbreaks of infectious diseases such as the current outbreak of the novel coronavirus (“COVID-19”), can result, and in the case of COVID-19 is resulting, in market volatility and disruption, and materially and adversely impact economic conditions in ways that cannot be predicted, all of which could result in substantial investment losses. The ultimate impact of COVID-19 or other health emergencies on global economic conditions and businesses is impossible to predict accurately. Ongoing and potential additional material adverse economic effects of indeterminate duration and severity are possible. The resulting adverse impact on the value of an investment in the Fund could be significant and prolonged. Other public health emergencies that may arise in the future could have similar or other unforeseen effects. 
•   LIBOR Risk: the risk associated with the transition away from LIBOR, which is used extensively in the U.S. and globally as a “benchmark” or “reference rate” for various commercial and financial contracts, including corporate bonds and other fixed income securities. The use of LIBOR is anticipated to begin being phased out by the end of 2021. There remains uncertainty regarding the future utilization of LIBOR and the nature of any replacement rate, 
   
and the transition from and ultimate abandonment of or modifications to LIBOR could have adverse impacts on newly issued financial instruments and existing financial instruments that reference LIBOR, including those in which the Fund invests. 
Please see “Principal Risks” and “Other Risks” for a more detailed description of the risks of investing in the Fund. 
Your investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency, entity, or person. 
METROPOLITAN WEST HIGH YIELD BOND FUND  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Metropolitan West High Yield Bond Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The High Yield Bond Fund seeks to maximize long-term total return consistent with preservation of capital.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock The table below describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2022
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
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. During the most recent fiscal year, the Fund’s portfolio turnover rate was 108% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 108.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The cost for the Fund reflects the net expenses of the Fund that result from the contractual expense limitation in the first year only (through July 31, 2022). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets, plus any borrowings for investment purposes, in high yield bonds (commonly known as “junk bonds”), which are bonds rated below investment grade or unrated bonds determined by the Adviser to be of comparable quality. The remainder of the Fund’s net assets may be invested in investment grade securities rated by one of the nationally recognized statistical rating organizations or, if unrated, determined by the Adviser to be of comparable quality. Under normal circumstances, the Fund’s portfolio duration is two to eight years and the Fund’s dollar-weighted average maturity ranges from two to fifteen years. Duration is a measure of the expected life of a fixed income security that is used to determine the sensitivity of a security to changes in interest rates. The Fund invests in the U.S. and abroad, including emerging markets, and may purchase securities of varying maturities issued by domestic and foreign corporations and governments. The Adviser focuses the Fund’s portfolio holdings in areas of the bond market that the Adviser believes to be relatively undervalued, based on its analysis of quality, sector, coupon or maturity, and that the Adviser believes offer attractive prospective risk-adjusted returns compared to other segments of the bond market. The Fund may invest up to 25% of its assets in foreign securities that are denominated in U.S. dollars. The Fund may invest up to 15% of its assets in securities of foreign issuers that are not denominated in U.S. dollars. The Fund may invest up to 10% of its assets in emerging market securities. The Fund’s investments include various types of bonds and debt securities, including corporate bonds, mezzanine investments, swaps (including credit default swaps), currency futures and options, bank loans, preferred stock, mortgage-related and asset-backed securities (including collateralized debt obligations, which in turn include collateralized bond obligations and collateralized loan obligations), foreign securities, U.S. Treasuries and agency securities, private placements, defaulted debt securities and restricted securities, cash and cash equivalents; and common stocks or other equity securities, such as warrants. The Fund’s fixed income investments may have interest rates that are fixed, variable or floating. Derivatives are used in an effort to hedge investments, for risk management, or to increase income or gains for the Fund. The Fund may also seek to obtain market exposure to the securities in which it invests by entering into a series of purchase and sale contracts or by using other investment techniques such as reverse repurchase agreements. The Fund may normally borrow or short sell up to 331/3% of the value of its total assets. The Fund may engage in active and frequent trading of portfolio securities to achieve its primary investment strategies.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock Because the Fund holds securities with fluctuating market prices, the value of the Fund’s shares will vary as its portfolio securities increase or decrease in value. Therefore, the value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. The principal risks affecting the Fund that can cause a decline in value are:   •   Debt Securities Risk: the risk that the value of a debt security may increase or decrease as a result of various factors, including changes in interest rates, actual or perceived inability or unwillingness of issuers to make principal or interest payments, market fluctuations and illiquidity in the debt securities market. •   Market Risk: the risk that returns from the securities in which the Fund invests may underperform returns from the general securities markets or other types of securities. •   Junk Bond Risk: the risk that junk bonds have a higher degree of default risk and may be less liquid and subject to greater price volatility than investment grade bonds. •   Interest Rate Risk: the risk that debt securities may decline in value because of changes in interest rates. •   Credit Risk: the risk that an issuer may default in the payment of principal and/or interest on a security. •   Price Volatility Risk: the risk that the value of the Fund’s investment portfolio will change as the prices of its investments go up or down. •   Issuer Risk: the risk that the value of a security may decline for reasons directly related to the issuer such as management performance, financial leverage and reduced demand for the issuer’s goods or services. •   Liquidity Risk: the risk that lack of a ready market or restrictions on resale may limit the ability of the Fund to sell a security at an advantageous time or price. In addition, the Fund, by itself or together with other accounts managed by the Adviser, may hold a position in a security that is large relative to the typical trading volume for that security, which can make it difficult for the Fund to dispose of the position at an advantageous time or price. Although the Fund is normally able to sell loans within seven days, a substantial portion of the loans held by the Fund may also experience delayed settlement beyond that period, which can impair the ability of the Fund to pay redemptions or to re-invest proceeds, or may require the Fund to borrow to meet redemptions. Over recent years, the fixed-income markets have grown more than the ability of dealers to make markets, which can further constrain liquidity and increase the volatility of portfolio valuations. High levels of redemptions in bond funds in response to market conditions could cause greater losses as a result. Regulations such as the Volcker Rule or future regulations may further constrain the ability of market participants to create liquidity, particularly in times of increased market volatility. The liquidity of the Fund’s assets may change over time. •   Frequent Trading Risk: the risk that frequent trading may lead to increased portfolio turnover and higher transaction     costs, which may reduce the Fund’s performance and may cause higher levels of current tax liability to shareholders of the Fund. •   Valuation Risk: the risk that the portfolio instruments may be sold at prices different from the values established by the Fund, particularly for investments that trade in low volume, in volatile markets or over the counter or that are fair valued. •   Unrated Securities Risk: the risk that unrated securities may be less liquid than comparable rated securities, and the risk that the Adviser may not accurately evaluate the security’s comparative credit rating. •   Distressed and Defaulted Securities Risk: the risk that the repayment of defaulted securities and obligations of distressed issuers is subject to significant uncertainties. •   Leverage Risk: the risk that leverage may result from certain transactions, including the use of derivatives and borrowing. This may impair the Fund’s liquidity, cause it to liquidate positions at an unfavorable time, increase its volatility or otherwise cause it not to achieve its intended result. To the extent required by applicable law or regulation, the Fund will reduce leverage risk by either segregating an equal amount of liquid assets or “covering” the transactions that introduce such risk. •   Counterparty Risk: the risk that the other party to a contract, such as a derivatives contract, may not fulfill its contractual obligations. •   Derivatives Risk: the risk of investing in derivative instruments, which includes liquidity, interest rate, market, credit and management risks as well as risks related to mispricing or improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, reference rate or index, and the Fund could lose more than the principal amount invested. These investments can create investment leverage and may create additional risks that may subject the Fund to greater volatility and less liquidity than investments in more traditional securities. •   Futures Contracts Risk: the risk of investing in futures contracts, which includes (1) the imperfect correlation between a futures contract and the change in market value of the underlying instrument held by the Fund; (2) a high degree of leverage because of the low collateral deposits normally involved in futures trading; (3) possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (4) losses caused by unanticipated market movements, which are potentially unlimited; and (5) the inability of the Fund to     execute a trade because of the maximum permissible price movements exchanges may impose on futures contracts. •   Swap Agreements Risk: the risk of investing in swaps, which, in addition to risks applicable to derivatives generally, includes: (1) the inability to assign a swap contract without the consent of the counterparty; (2) potential default of the counterparty to a swap for those not traded through a central counterparty; (3) absence of a liquid secondary market for any particular swap at any time; and (4) possible inability of the Fund to close out a swap transaction at a time that otherwise would be favorable for it to do so. •   Bank Loan Risk: the risk of investing in corporate loans made by commercial banks and other financial institutions or institutional investors to companies that need capital to grow or restructure, which includes interest rate risk, liquidity risk and prepayment risk. The Fund may also be subject to the credit risk of other financial institutions and the risks associated with insufficient collateral securing a bank loan, limited available public information about a bank loan, delayed settlement, and less protection for holders of bank loans as compared to holders of registered securities. •   Foreign Investing Risk: the risk that Fund share prices will fluctuate with market conditions, currency exchange rates and the economic and political climates of the foreign countries in which the Fund invests or has exposure. Investments in foreign securities may involve greater risks than investing in U.S. securities due to, among other factors, less publicly available information, less stringent and less uniform accounting, auditing and financial reporting standards, less liquid and more volatile markets, higher transaction and custody costs, additional taxes, less investor protection, delayed or less frequent settlement, political or social instability, civil unrest, acts of terrorism, regional economic volatility, and the imposition of sanctions, confiscations, trade restrictions (including tariffs) and other government restrictions by the United States and/or other governments. •   Foreign Currency Risk: the risk that foreign currencies may decline in value relative to the U.S. dollar and affect the Fund’s investments in foreign currencies, in securities that are denominated, trade and/or receive revenues in foreign currencies, or in derivatives that provide exposure to foreign currencies. •   Emerging Markets Risk: the risk of investing in emerging market countries, which is substantial due to, among other factors, higher brokerage costs in certain countries; different accounting standards; thinner trading markets as     compared to those in developed countries; less publicly available and reliable information about issuers as compared to developed markets; the possibility of currency transfer restrictions; and the risk of expropriation, nationalization or other adverse political, economic or social developments. •   Short Sales Risk: the risk that the use of short sales, which are speculative investments, may cause the Fund to lose money if the value of a security does not go down as the Adviser expects. The risk of loss is theoretically unlimited if the value of the security sold short continues to increase. In addition, the use of borrowing and short sales may cause the Fund to have higher expenses (especially interest and dividend expenses) than those of other mutual funds that do not engage in short sales. •   U.S. Government Securities Risk: the risk that debt securities issued or guaranteed by certain U.S. government agencies, instrumentalities, and sponsored enterprises are not supported by the full faith and credit of the U.S. government, and as a result, investments in their securities or obligations issued by such entities involve credit risk greater than investments in other types of U.S. government securities. •   Securities Selection Risk: the risk that the securities held by the Fund may underperform those held by other funds investing in the same asset class or those included in benchmarks that are representative of the same asset class because of the portfolio managers’ choice of securities. •   Portfolio Management Risk: the risk that an investment strategy may fail to produce the intended results. •   Prepayment Risk: the risk that in times of declining interest rates, the Fund’s higher yielding securities may be prepaid and the Fund may have to replace them with securities having a lower yield. •   Extension Risk: the risk that in times of rising interest rates, borrowers may pay off their debt obligations more slowly, causing securities considered short or intermediate term to become longer-term securities that fluctuate more widely in response to changes in interest rates than shorter term securities. •   Mezzanine Securities Risk: the risk of investing in mezzanine securities, which generally are rated below investment grade or are unrated and present many of the same risks as senior loans, second lien loans and non-investment grade bonds. Mezzanine securities present additional risks because they typically are the most subordinated debt obligation in an issuer’s capital structure and are often unsecured. Mezzanine securities are also expected to be a highly illiquid investment. •   Public Health Emergency Risk: the risk that pandemics and other public health emergencies, including outbreaks of infectious diseases such as the current outbreak of the novel coronavirus (“COVID-19”), can result, and in the case of COVID-19 is resulting, in market volatility and disruption, and materially and adversely impact economic conditions in ways that cannot be predicted, all of which could result in substantial investment losses. The ultimate impact of COVID-19 or other health emergencies on global economic conditions and businesses is impossible to predict accurately. Ongoing and potential additional material adverse economic effects of indeterminate duration and severity are possible. The resulting adverse impact on the value of an investment in the Fund could be significant and prolonged. Other public health emergencies that may arise in the future could have similar or other unforeseen effects. •   LIBOR Risk: the risk associated with the transition away from LIBOR, which is used extensively in the U.S. and globally as a “benchmark” or “reference rate” for various commercial and financial contracts, including corporate bonds and other fixed income securities. The use of LIBOR is anticipated to begin being phased out by the end of 2021. There remains uncertainty regarding the future utilization of LIBOR and the nature of any replacement rate, and the transition from and ultimate abandonment of or modifications to LIBOR could have adverse impacts on newly issued financial instruments and existing financial instruments that reference LIBOR, including those in which the Fund invests. Please see “Principal Risks” and “Other Risks” for a more detailed description of the risks of investing in the Fund. Your investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency, entity, or person.
Risk Lose Money [Text] rr_RiskLoseMoney You can lose money by investing in the Fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution Your investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency, entity, or person.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance Information
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year. The bar chart shows performance of the Fund’s Class M shares. Class M performance is lower than Class I performance because Class I has lower expenses than Class M. The table compares the average annual total returns of the Fund to a broad-based securities market index. Total returns would have been lower if certain fees and expenses had not been waived or reimbursed. The inception dates of Class M shares and Class I shares of the Fund are September 30, 2002 and March 31, 2003, respectively. The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance information for the Fund is available on our website at www.tcw.com or by calling (800) 241-4671.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year. The bar chart shows performance of the Fund’s Class M shares. Class M performance is lower than Class I performance because Class I has lower expenses than Class M. The table compares the average annual total returns of the Fund to a broad-based securities market index.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone (800) 241-4671
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.tcw.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading High Yield Bond Fund – Class M SharesAnnual Total Returns for Years Ended 12/31
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock   Year-to-Date Total Return of Class M Shares as of June 30, 2021: 2.15% Highest:        8.60%    (quarter ended June 30, 2020) Lowest:        -8.55%    (quarter ended September 30, 2011)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (For Periods Ended December 31, 2020)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred After-tax returns shown are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for only Class M Shares. After-tax returns for other classes will vary.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In some cases, returns after taxes on distributions and sale of Fund sharesmay be higher than returns before taxes because the calculations assume that the investor received a tax deduction for any loss incurred on the sale of the shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for only Class M Shares. After-tax returns for other classes will vary. In some cases, returns after taxes on distributions and sale of Fund sharesmay be higher than returns before taxes because the calculations assume that the investor received a tax deduction for any loss incurred on the sale of the shares.
METROPOLITAN WEST HIGH YIELD BOND FUND | M Class  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees (Fees paid directly from your investment) rr_ShareholderFeeOther none
Management Fees rr_ManagementFeesOverAssets 0.50%
Distribution (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Shareholder Servicing Expenses rr_Component1OtherExpensesOverAssets 0.09% [1]
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.91%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Total Annual Fund Operating Expenses after Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.85%
1 Year rr_ExpenseExampleYear01 $ 87
3 Years rr_ExpenseExampleYear03 284
5 Years rr_ExpenseExampleYear05 498
10 Years rr_ExpenseExampleYear10 $ 1,114
2011 rr_AnnualReturn2011 0.35%
2012 rr_AnnualReturn2012 14.20%
2013 rr_AnnualReturn2013 6.84%
2014 rr_AnnualReturn2014 0.34%
2015 rr_AnnualReturn2015 (2.18%)
2016 rr_AnnualReturn2016 7.92%
2017 rr_AnnualReturn2017 6.22%
2018 rr_AnnualReturn2018 (1.27%)
2019 rr_AnnualReturn2019 12.27%
2020 rr_AnnualReturn2020 11.45%
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-Date Total Return of Class M Shares as of June 30, 2021:
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2021
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 2.15%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.60%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.55%)
1 Year rr_AverageAnnualReturnYear01 11.45%
5 Years rr_AverageAnnualReturnYear05 7.21%
10 Years rr_AverageAnnualReturnYear10 5.46%
Since Inception rr_AverageAnnualReturnSinceInception 8.25%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2002
METROPOLITAN WEST HIGH YIELD BOND FUND | I Class  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees (Fees paid directly from your investment) rr_ShareholderFeeOther none
Management Fees rr_ManagementFeesOverAssets 0.50%
Distribution (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Shareholder Servicing Expenses rr_Component1OtherExpensesOverAssets 0.05% [1]
Other Expenses rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.61%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Total Annual Fund Operating Expenses after Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.60%
1 Year rr_ExpenseExampleYear01 $ 61
3 Years rr_ExpenseExampleYear03 194
5 Years rr_ExpenseExampleYear05 339
10 Years rr_ExpenseExampleYear10 $ 761
1 Year rr_AverageAnnualReturnYear01 11.73%
5 Years rr_AverageAnnualReturnYear05 7.47%
10 Years rr_AverageAnnualReturnYear10 5.72%
Since Inception rr_AverageAnnualReturnSinceInception 7.71%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2003
METROPOLITAN WEST HIGH YIELD BOND FUND | After Taxes on Distributions | M Class  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 9.76%
5 Years rr_AverageAnnualReturnYear05 5.51%
10 Years rr_AverageAnnualReturnYear10 3.29%
Since Inception rr_AverageAnnualReturnSinceInception 5.36%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2002
METROPOLITAN WEST HIGH YIELD BOND FUND | After Taxes on Distributions and Sale of Fund Shares | M Class  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 6.71%
5 Years rr_AverageAnnualReturnYear05 4.80%
10 Years rr_AverageAnnualReturnYear10 3.24%
Since Inception rr_AverageAnnualReturnSinceInception 5.29%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2002
METROPOLITAN WEST HIGH YIELD BOND FUND | Barclays Capital U.S. Corporate High Yield Index – 2% Issuer Cap  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 7.05%
5 Years rr_AverageAnnualReturnYear05 8.56%
10 Years rr_AverageAnnualReturnYear10 6.78%
Since Inception rr_AverageAnnualReturnSinceInception 8.75%
[1]
The Fund is authorized to compensate broker-dealers and other third-party intermediaries up to 0.10% (10 basis points) of the M and I Class assets serviced by those intermediaries for shareholder services.
[2]
Metropolitan West Asset Management, LLC (the “Adviser”) has contractually agreed to reduce advisory fees and/or reimburse expenses, including distribution expenses, to limit the Fund’s total annual operating expenses (excluding interest, taxes, brokerage commissions, short sale dividend expenses, swap interest expenses, acquired fund fees and expenses, and any expenses incurred in connection with any merger or reorganization or extraordinary expenses such as litigation) to the net expenses shown in the table for the applicable class. The Adviser may recoup reduced fees and expenses only within three years of the waiver or reimbursement, provided that the recoupment does not cause the Fund’s annual expense ratio to exceed the lesser of (i) the expense limitation applicable at the time of that fee waiver and/or expense reimbursement or (ii) the expense limitation in effect at the time of recoupment. This contract will remain in place until July 31, 2022. Although it does not expect to do so, the Board of Trustees is permitted to terminate that contract sooner in its discretion with written notice to the Adviser.