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METROPOLITAN WEST LOW DURATION BOND FUND  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Metropolitan West Low Duration Bond Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Low Duration Bond Fund seeks to maximize current income, 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)
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 347% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 347.00%
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. 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 70% of its net assets in highly rated fixed income securities or unrated securities determined by the Adviser to be of comparable quality. Up to 30% of the Fund’s net assets may be invested in securities rated below highly rated securities or unrated securities determined by the Adviser to be of comparable quality, but not more than 20% of the Fund’s net assets may be invested in securities rated below investment grade (commonly known as “junk bonds”) or unrated securities determined by the Adviser to be of comparable quality. The Fund also invests, under normal circumstances, at least 80% of its net assets, plus any borrowings for investment purposes, in fixed income securities it regards as bonds. A bond is a security or instrument having one or more of the following characteristics: a fixed-income security, a security issued at a discount to its face value, a security that pays interest or a security with a stated principal amount that requires repayment of some or all of that principal amount to the holder of the security. The term “bond” is interpreted broadly by the Adviser as an instrument or security evidencing a promise to pay some amount rather than evidencing the corporate ownership of equity, unless that equity represents an indirect or derivative interest in one or more bonds. Under normal circumstances, the Fund’s portfolio duration is up to three years and the Fund’s dollar-weighted average maturity ranges from one to five 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 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, notes, mortgage-related and asset-backed securities (including collateralized debt obligations, which in turn include collateralized bond obligations and collateralized loan obligations), bank loans, U.S. and non-U.S. money market securities, swaps (including credit default swaps), futures, options (including swaptions), municipal securities, defaulted debt securities, private placements and restricted securities. 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 engage in active and frequent trading of portfolio securities to achieve its primary investment strategies. 
The Fund may normally short sell up to 25% of the value of its total assets. 
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. 
•   Credit Risk: the risk that an issuer may default in the payment of principal and/or interest on a security. 
•   Inflation Risk: the risk that the value of the Fund’s investments may not keep up with price increases from inflation. 
•   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. 
•   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. 
•   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. 
•   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. 
•   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. 
•  
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 interest 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. 
•   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. 
•   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. 
•   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. 
•   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. In addition, Russia’s recent military incursions in Ukraine have led to, and may lead to additional, sanctions being levied by the United States, European Union and other countries against Russia. Russia’s military incursion and the resulting sanctions could 
   
adversely affect global energy and financial markets and thus could affect the value of the Fund’s investments. 
•   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. 
•   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. 
•   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. 
•   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. 
•   Portfolio Management Risk: the risk that an investment strategy may fail to produce the intended results. 
•  
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. 
•   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. 
•   Distressed and Defaulted Securities Risk: the risk that the repayment of defaulted securities and obligations of distressed issuers is subject to significant uncertainties. 
•   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. 
•   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 securities or obligations issued by such entities involve credit risk greater than investments in other types of U.S. government securities. 
•   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 has resulted and may continue to result, 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, including new variants of the underlying virus, 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 began being phased out at the end of 2021; however, the publication of 1-month, 3-month and 6-month USD LIBOR has been extended until June 2023. Although the transition process away from LIBOR has become increasingly well-defined, there remains uncertainty regarding the impact on the Fund of the transition to a new reference rate. 
•   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. 
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 the performance of the Fund’s Class M Shares. Class M performance is lower than Class I performance and
higher than Administrative Class performance because Class M has higher expenses than Class I and lower expenses than Administrative Class. 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, Class I shares and Administrative Class shares of the Fund are March 31, 1997, March 31, 2000 and September 23, 2009, 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 the performance of the Fund’s Class M Shares. Class M performance is lower than Class I performance andhigher than Administrative Class performance because Class M has higher expenses than Class I and lower expenses than Administrative Class. 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 Low Duration Bond Fund – Class M Shares  Annual 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, 2022: -4.35% 
Highest:        2.98%    (quarter ended September 30, 2012)
Lowest:        -0.79%    (quarter ended March 31, 2020)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (For Periods Ended December 31, 2021)
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 shares may 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 shares may 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 LOW DURATION BOND FUND | M Class  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees (Fees paid directly from your investment) rr_ShareholderFeeOther none
Management Fees rr_ManagementFeesOverAssets 0.30%
Distribution (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.19%
Shareholder Servicing Expenses rr_Component1OtherExpensesOverAssets 0.10% [1]
Other Expenses rr_OtherExpensesOverAssets 0.13%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.62%
1 Year rr_ExpenseExampleYear01 $ 63
3 Years rr_ExpenseExampleYear03 199
5 Years rr_ExpenseExampleYear05 346
10 Years rr_ExpenseExampleYear10 $ 774
2012 rr_AnnualReturn2012 7.54%
2013 rr_AnnualReturn2013 1.93%
2014 rr_AnnualReturn2014 1.39%
2015 rr_AnnualReturn2015 0.20%
2016 rr_AnnualReturn2016 1.23%
2017 rr_AnnualReturn2017 1.15%
2018 rr_AnnualReturn2018 1.20%
2019 rr_AnnualReturn2019 4.23%
2020 rr_AnnualReturn2020 3.27%
2021 rr_AnnualReturn2021 (0.13%)
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-Date Total Return of Class M Shares as of June 30, 2022:
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2022
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (4.35%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2012
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 2.98%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (0.79%)
1 Year rr_AverageAnnualReturnYear01 (0.13%)
5 Years rr_AverageAnnualReturnYear05 1.93%
10 Years rr_AverageAnnualReturnYear10 2.18%
Since Inception rr_AverageAnnualReturnSinceInception 3.45%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 1997
METROPOLITAN WEST LOW DURATION BOND FUND | I Class  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees (Fees paid directly from your investment) rr_ShareholderFeeOther none
Management Fees rr_ManagementFeesOverAssets 0.30%
Distribution (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Shareholder Servicing Expenses rr_Component1OtherExpensesOverAssets 0.08% [1]
Other Expenses rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.41%
1 Year rr_ExpenseExampleYear01 $ 42
3 Years rr_ExpenseExampleYear03 132
5 Years rr_ExpenseExampleYear05 230
10 Years rr_ExpenseExampleYear10 $ 518
1 Year rr_AverageAnnualReturnYear01 0.07%
5 Years rr_AverageAnnualReturnYear05 2.14%
10 Years rr_AverageAnnualReturnYear10 2.39%
Since Inception rr_AverageAnnualReturnSinceInception 3.15%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2000
METROPOLITAN WEST LOW DURATION BOND FUND | Administrative Class  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees (Fees paid directly from your investment) rr_ShareholderFeeOther none
Management Fees rr_ManagementFeesOverAssets 0.30%
Distribution (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.19%
Shareholder Servicing Expenses rr_Component1OtherExpensesOverAssets 0.20% [1]
Other Expenses rr_OtherExpensesOverAssets 0.23%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.72%
1 Year rr_ExpenseExampleYear01 $ 74
3 Years rr_ExpenseExampleYear03 230
5 Years rr_ExpenseExampleYear05 401
10 Years rr_ExpenseExampleYear10 $ 894
1 Year rr_AverageAnnualReturnYear01 (0.27%)
5 Years rr_AverageAnnualReturnYear05 1.83%
10 Years rr_AverageAnnualReturnYear10 2.05%
Since Inception rr_AverageAnnualReturnSinceInception 2.93%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2009
METROPOLITAN WEST LOW DURATION BOND FUND | After Taxes on Distributions | M Class  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (0.49%)
5 Years rr_AverageAnnualReturnYear05 1.25%
10 Years rr_AverageAnnualReturnYear10 1.48%
Since Inception rr_AverageAnnualReturnSinceInception 1.94%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 1997
METROPOLITAN WEST LOW DURATION BOND FUND | After Taxes on Distributions and Sale of Fund Shares | M Class  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (0.08%)
5 Years rr_AverageAnnualReturnYear05 1.18%
10 Years rr_AverageAnnualReturnYear10 1.37%
Since Inception rr_AverageAnnualReturnSinceInception 2.03%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 1997
METROPOLITAN WEST LOW DURATION BOND FUND | BofA Merrill Lynch 1-3 Year U.S. Treasury Index  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (0.55%)
5 Years rr_AverageAnnualReturnYear05 1.61%
10 Years rr_AverageAnnualReturnYear10 1.09%
Since Inception rr_AverageAnnualReturnSinceInception 3.04%
[1]
Shareholder Servicing Expenses for the Administrative Class Shares includes up to 0.20% charged under the Shareholder Servicing Plan. 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.