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<!-- EDGAR Online I-Metrix Xcelerate Instance Document, based on XBRL 2.1  http://www.edgar-online.com/ -->
<!-- Version:  6.20.1 -->
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<!-- Creation date: 2012-10-29T18:03:03Z -->
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  <dei:DocumentCreationDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0" id="id_399924_634E7703-43ED-42E3-B1CB-35C80AD5DD4C_1_0">2012-10-26</dei:DocumentCreationDate>
  <rr:ProspectusDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0" id="id_399924_634E7703-43ED-42E3-B1CB-35C80AD5DD4C_1_2">2012-10-31</rr:ProspectusDate>
  <rr:ExpenseExampleWithRedemptionTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_58">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/ExpenseExample_S000004051Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:ExpenseExampleWithRedemptionTableTextBlock>
  <rr:BarChartTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_57">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/BarChartData_S000004051Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:BarChartTableTextBlock>
  <rr:ThirtyDayYieldPhone contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_55">(800) 869-NEWS</rr:ThirtyDayYieldPhone>
  <rr:ObjectivePrimaryTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_3">&lt;tt&gt;Active Assets Tax-Free Trust is a money market fund that seeks to provide as&lt;br /&gt;high a level of daily income exempt from federal personal income tax as is&lt;br /&gt;consistent with stability of principal and liquidity.&lt;/tt&gt;</rr:ObjectivePrimaryTextBlock>
  <rr:ExpenseExampleNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_15">&lt;tt&gt;The example below is intended to help you compare the cost of investing in the&lt;br /&gt;Fund with the cost of investing in other mutual funds.&lt;br /&gt; &lt;br /&gt;The example assumes that you invest $10,000 in the Fund, your investment has a&lt;br /&gt;5% return each year, and the Fund&apos;s operating expenses remain the same. Although&lt;br /&gt;your actual costs may be higher or lower, based on these assumptions your costs&lt;br /&gt;would be:&lt;/tt&gt;</rr:ExpenseExampleNarrativeTextBlock>
  <rr:StrategyNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_21">&lt;tt&gt;The Fund will invest in high quality, short-term securities that are normally&lt;br /&gt;municipal obligations that pay interest exempt from federal income taxes. The&lt;br /&gt;Adviser seeks to maintain the Fund&apos;s share price at $1.00. The Fund has a&lt;br /&gt;fundamental policy of investing at least 80% of its net assets in securities &lt;br /&gt;the interest on which is exempt from federal personal income tax. This policy &lt;br /&gt;may not be changed without shareholder approval. In addition, the Fund may &lt;br /&gt;invest up to 20% of its net assets in securities that pay interest income &lt;br /&gt;subject to the "alternative minimum tax," and some taxpayers may have to pay &lt;br /&gt;tax on a Fund distribution of this income. For more information, please see &lt;br /&gt;the "Tax Consequences" section beginning on page 26 of this Prospectus.&lt;br /&gt; &lt;br /&gt;Municipal obligations are securities issued by state and local governments and&lt;br /&gt;their agencies. These securities typically are "general obligation" or "revenue"&lt;br /&gt;bonds, notes or commercial paper, including participations in lease obligations&lt;br /&gt;and installment purchase contracts of municipalities.&lt;br /&gt; &lt;br /&gt;The Fund may purchase debt obligations that have fixed, variable or floating&lt;br /&gt;rates of interest. The interest rates payable on variable or floating rate&lt;br /&gt;obligations may fluctuate based upon changes in market rates.&lt;br /&gt; &lt;br /&gt;The Fund&apos;s investments may include tender option bonds and custodial receipts.&lt;br /&gt;Tender option bonds are municipal obligations held pursuant to a custodial&lt;br /&gt;arrangement and issued pursuant to an agreement with a third-party such as a&lt;br /&gt;bank or financial institution to provide the holder with the option of tendering &lt;br /&gt;the bond at periodic intervals. The holder of the tender option bond effectively &lt;br /&gt;holds a demand obligation that bears interest at prevailing short-term rates. &lt;br /&gt;Custodial receipts represent interests in future interest and/or principal &lt;br /&gt;payments on U.S. government securities or municipal obligations. Additionally, &lt;br /&gt;the Fund may invest in investment companies, including money market funds some &lt;br /&gt;or all of which may be advised or managed by the Adviser or its affiliates.&lt;/tt&gt;</rr:StrategyNarrativeTextBlock>
  <rr:RiskReturnHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_1">Active Assets Tax-Free Trust</rr:RiskReturnHeading>
  <rr:ExpenseExampleHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_14">Example</rr:ExpenseExampleHeading>
  <rr:ObjectiveHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_2">Investment Objective</rr:ObjectiveHeading>
  <rr:PerformancePastDoesNotIndicateFuture contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_29">The Fund&apos;s past performance does not indicate how the Fund will perform in the future.</rr:PerformancePastDoesNotIndicateFuture>
  <rr:RiskHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_22">Principal Risks</rr:RiskHeading>
  <rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_12">These fee waivers and/or expense reimbursements will continue for at least one year
or until such time as the Fund&apos;s Board of Trustees acts to discontinue all or a
portion of such waivers and/or expense reimbursements when it deems such action
appropriate.</rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
  <rr:BarChartHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_30">Annual Total Returns--Calendar Years</rr:BarChartHeading>
  <rr:BarChartAndPerformanceTableHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_26">Past Performance</rr:BarChartAndPerformanceTableHeading>
  <rr:PerformanceTableClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_56">&lt;tt&gt;For the Fund&apos;s most recent 7-day annualized yield you may call toll-free (800)&lt;br /&gt;869-NEWS.&lt;/tt&gt;</rr:PerformanceTableClosingTextBlock>
  <rr:PerformanceInformationIllustratesVariabilityOfReturns contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_28">The bar chart and table below provide some indication of the risks of investing
in the Fund by showing changes in the Fund&apos;s performance from year to year and
by showing the Fund&apos;s average annual returns for the one, five and 10 year periods.</rr:PerformanceInformationIllustratesVariabilityOfReturns>
  <rr:BarChartClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_50">&lt;tt&gt;The year-to-date total return as of September 30, 2012 was 0.01%.&lt;br /&gt; &lt;br /&gt;High Quarter 6/30/07 0.83%&lt;br /&gt; &lt;br /&gt;Low Quarter 3/31/11 0.00%&lt;/tt&gt;</rr:BarChartClosingTextBlock>
  <rr:OperatingExpensesCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_6">Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)</rr:OperatingExpensesCaption>
  <rr:AverageAnnualReturnCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_51">Average Annual Total Returns (as of December 31, 2011)</rr:AverageAnnualReturnCaption>
  <rr:RiskMoneyMarketFund contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_24">Although the Fund seeks to preserve the value of your investment at $1.00 per share,
if it is unable to do so, it is possible to lose money by investing in the Fund.</rr:RiskMoneyMarketFund>
  <rr:RiskNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_23">&lt;tt&gt;There is no assurance that the Fund will achieve its investment objectives.&lt;br /&gt;Although the Fund seeks to preserve the value of your investment at $1.00 per&lt;br /&gt;share, if it is unable to do so, it is possible to lose money by investing in&lt;br /&gt;the Fund. The principal risks of investing in the Fund include:&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Credit and Interest Rate Risk. Debt obligations, such as bonds, are subject &lt;br /&gt;&amp;#xA0;&amp;#xA0;to two types of risk: credit risk and interest rate risk. Credit risk refers &lt;br /&gt;&amp;#xA0;&amp;#xA0;to thepossibility that the issuer of a security will be unable to make interest&lt;br /&gt;&amp;#xA0;&amp;#xA0;payments and/or repay the principal on its debt. In the case of revenue bonds,&lt;br /&gt;&amp;#xA0;&amp;#xA0;notes or commercial paper, for example, the credit risk is the possibility that&lt;br /&gt;&amp;#xA0;&amp;#xA0;the user fees from a project or other specified revenue sources are insufficient&lt;br /&gt;&amp;#xA0;&amp;#xA0;to meet interest and/or principal payment obligations. Interest rate risk refers&lt;br /&gt;&amp;#xA0;&amp;#xA0;to fluctuations in the value of a debt security resulting from changes in the&lt;br /&gt;&amp;#xA0;&amp;#xA0;general level of interest rates.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Tender Option Bonds and Custodial Receipts. The risks of tender option bonds&lt;br /&gt;&amp;#xA0;&amp;#xA0;and custodial receipts include the risk that the owner of such instruments may&lt;br /&gt;&amp;#xA0;&amp;#xA0;not be considered the owner for federal income tax purposes and thus will not be&lt;br /&gt;&amp;#xA0;&amp;#xA0;entitled to treat such interest as exempt from federal income tax. Additionally,&lt;br /&gt;&amp;#xA0;&amp;#xA0;the occurrence of certain defaults or a credit rating downgrade on the underlying &lt;br /&gt;&amp;#xA0;&amp;#xA0;security may impair the ability to tender the bond or receipt back to the third-party &lt;br /&gt;&amp;#xA0;&amp;#xA0;provider of the demand option, thus causing the bond or receipt to become illiquid.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Investment Companies. An investment in an investment company is subject to the&lt;br /&gt;&amp;#xA0;&amp;#xA0;underlying risks of that investment company&apos;s portfolio securities. In addition&lt;br /&gt;&amp;#xA0;&amp;#xA0;to the Fund&apos;s fees and expenses, the Fund generally would bear its share of the&lt;br /&gt;&amp;#xA0;&amp;#xA0;investment company&apos;s fees and expenses.&lt;br /&gt; &lt;br /&gt;Shares of the Fund are not bank deposits and are not guaranteed or insured by&lt;br /&gt;the FDIC or any other government agency.&lt;/tt&gt;</rr:RiskNarrativeTextBlock>
  <rr:ExpenseHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_4">Fees and Expenses</rr:ExpenseHeading>
  <rr:StrategyHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_20">Principal Investment Strategies</rr:StrategyHeading>
  <rr:PerformanceNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_27">&lt;tt&gt;The bar chart and table below provide some indication of the risks of investing&lt;br /&gt;in the Fund by showing changes in the Fund&apos;s performance from year to year and&lt;br /&gt;by showing the Fund&apos;s average annual returns for the one, five and 10 year&lt;br /&gt;periods. The Fund&apos;s past performance does not indicate how the Fund will perform&lt;br /&gt;in the future.&lt;/tt&gt;</rr:PerformanceNarrativeTextBlock>
  <rr:ExpenseNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_5">&lt;tt&gt;The table below describes the fees and expenses that you may pay if you buy and&lt;br /&gt;hold shares of the Fund. The Fund is a no-load fund. The Fund does not impose&lt;br /&gt;any sales charges.&lt;/tt&gt;</rr:ExpenseNarrativeTextBlock>
  <rr:AnnualFundOperatingExpensesTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_59">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/OperatingExpensesData_S000004051Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:AnnualFundOperatingExpensesTableTextBlock>
  <rr:PerformanceTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_60">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/PerformanceTableData_S000004051Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:PerformanceTableTextBlock>
  <rr:RiskNotInsuredDepositoryInstitution contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1001_25">Shares of the Fund are not bank deposits and are not guaranteed or insured by the FDIC or any other government agency.</rr:RiskNotInsuredDepositoryInstitution>
  <dei:TradingSymbol contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_0">AATXX</dei:TradingSymbol>
  <rr:AnnualReturn2002 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_31">0.0099</rr:AnnualReturn2002>
  <rr:LowestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_47">Low Quarter</rr:LowestQuarterlyReturnLabel>
  <rr:HighestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_44">High Quarter</rr:HighestQuarterlyReturnLabel>
  <rr:BarChartYearToDateReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_43">2012-09-30</rr:BarChartYearToDateReturnDate>
  <rr:ExpenseExampleYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="iso4217_USD" decimals="0" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_16">14</rr:ExpenseExampleYear01>
  <rr:BarChartHighestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_46">2007-06-30</rr:BarChartHighestQuarterlyReturnDate>
  <rr:ExpenseExampleYear03 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="iso4217_USD" decimals="0" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_17">45</rr:ExpenseExampleYear03>
  <rr:BarChartLowestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_48">0.0000</rr:BarChartLowestQuarterlyReturn>
  <rr:AnnualReturn2004 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_33">0.0074</rr:AnnualReturn2004>
  <rr:FeeWaiverOrReimbursementOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_11">-0.0027</rr:FeeWaiverOrReimbursementOverAssets>
  <rr:AnnualReturn2010 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_39">0.0001</rr:AnnualReturn2010>
  <rr:ExpenseExampleYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="iso4217_USD" decimals="0" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_19">179</rr:ExpenseExampleYear10>
  <rr:ExpenseExampleYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="iso4217_USD" decimals="0" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_18">79</rr:ExpenseExampleYear05>
  <rr:AnnualReturn2007 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_36">0.0328</rr:AnnualReturn2007>
  <rr:BarChartHighestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_45">0.0083</rr:BarChartHighestQuarterlyReturn>
  <rr:AverageAnnualReturnYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_52">0.0001</rr:AverageAnnualReturnYear01>
  <rr:OtherExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_9">0.0007</rr:OtherExpensesOverAssets>
  <rr:AnnualReturn2008 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_37">0.0173</rr:AnnualReturn2008>
  <rr:ManagementFeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_7">0.0024</rr:ManagementFeesOverAssets>
  <rr:BarChartLowestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_49">2011-03-31</rr:BarChartLowestQuarterlyReturnDate>
  <rr:AnnualReturn2009 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_38">0.0004</rr:AnnualReturn2009>
  <rr:AverageAnnualReturnYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_53">0.0101</rr:AverageAnnualReturnYear05>
  <rr:AnnualReturn2005 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_34">0.0194</rr:AnnualReturn2005>
  <rr:YearToDateReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_41">The year-to-date total return</rr:YearToDateReturnLabel>
  <rr:AnnualReturn2011 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_40">0.0001</rr:AnnualReturn2011>
  <rr:AnnualReturn2003 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_32">0.0057</rr:AnnualReturn2003>
  <rr:DistributionAndService12b1FeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_8">0.0010</rr:DistributionAndService12b1FeesOverAssets>
  <rr:AverageAnnualReturnYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_54">0.0123</rr:AverageAnnualReturnYear10>
  <rr:NetExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_13">0.0014</rr:NetExpensesOverAssets>
  <rr:ExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_10">0.0041</rr:ExpensesOverAssets>
  <rr:AnnualReturn2006 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_35">0.0301</rr:AnnualReturn2006>
  <rr:BarChartYearToDateReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980215_602238x-9980211_602488x-9980220" unitRef="pure" decimals="4" id="id_399924_65D41FAF-6AEE-4881-A477-14FD00EAD75D_1002_42">0.0001</rr:BarChartYearToDateReturn>
  <rr:ExpenseExampleWithRedemptionTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_58">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/ExpenseExample_S000004050Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:ExpenseExampleWithRedemptionTableTextBlock>
  <rr:BarChartTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_57">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/BarChartData_S000004050Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:BarChartTableTextBlock>
  <rr:ObjectivePrimaryTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_3">&lt;tt&gt;Active Assets Money Trust is a money market fund that seeks to provide high&lt;br /&gt;current income, preservation of capital and liquidity.&lt;/tt&gt;</rr:ObjectivePrimaryTextBlock>
  <rr:ExpenseExampleNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_15">&lt;tt&gt;The example below is intended to help you compare the cost of investing in the&lt;br /&gt;Fund with the cost of investing in other mutual funds.&lt;br /&gt; &lt;br /&gt;The example assumes that you invest $10,000 in the Fund, your investment has a&lt;br /&gt;5% return each year, and the Fund&apos;s operating expenses remain the same. Although&lt;br /&gt;your actual costs may be higher or lower, based on these assumptions your costs&lt;br /&gt;would be:&lt;/tt&gt;</rr:ExpenseExampleNarrativeTextBlock>
  <rr:StrategyNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_21">&lt;tt&gt;The Fund invests in high quality, short-term debt obligations. In selecting&lt;br /&gt;investments, the Adviser and/or Morgan Stanley Investment Management Limited&lt;br /&gt;("Sub-Adviser") seek to maintain the Fund&apos;s share price at $1.00. The Fund&apos;s&lt;br /&gt;investments include the following money market instruments: corporate&lt;br /&gt;obligations (including but not limited to commercial paper); debt obligations &lt;br /&gt;of U.S.-regulated banks (including domestic branches or subsidiaries of foreign&lt;br /&gt;banks) and instruments secured by those obligations (including certificates of&lt;br /&gt;deposit); certificates of deposit of savings banks and savings and loan&lt;br /&gt;associations; debt obligations issued or guaranteed as to principal and interest&lt;br /&gt;by the U.S. Government, its agencies or instrumentalities, including U.S.&lt;br /&gt;government securities guaranteed under the Federal Deposit Insurance Corporation&lt;br /&gt;("FDIC") Temporary Liquidity Guarantee Program; asset-backed securities; U.S.&lt;br /&gt;dollar-denominated foreign bank obligations; and repurchase agreements.&lt;/tt&gt;</rr:StrategyNarrativeTextBlock>
  <rr:RiskReturnHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_1">Active Assets Money Trust</rr:RiskReturnHeading>
  <rr:ExpenseExampleHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_14">Example</rr:ExpenseExampleHeading>
  <rr:ObjectiveHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_2">Investment Objectives</rr:ObjectiveHeading>
  <rr:PerformancePastDoesNotIndicateFuture contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_29">The Fund&apos;s past performance does not indicate how the Fund will perform in the future.</rr:PerformancePastDoesNotIndicateFuture>
  <rr:RiskHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_22">Principal Risks</rr:RiskHeading>
  <rr:BarChartHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_30">Annual Total Returns--Calendar Years</rr:BarChartHeading>
  <rr:BarChartAndPerformanceTableHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_26">Past Performance</rr:BarChartAndPerformanceTableHeading>
  <rr:PerformanceTableClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_56">&lt;tt&gt;For the Fund&apos;s most recent 7-day annualized yield you may call toll-free (800)&lt;br /&gt;869-NEWS.&lt;/tt&gt;</rr:PerformanceTableClosingTextBlock>
  <rr:PerformanceInformationIllustratesVariabilityOfReturns contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_28">The bar chart and table below provide some indication of the risks of investing in
the Fund by showing changes in the Fund&apos;s performance from year to year and by showing
the Fund&apos;s average annual returns for the one, five and 10 year periods.</rr:PerformanceInformationIllustratesVariabilityOfReturns>
  <rr:BarChartClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_50">&lt;tt&gt;The year-to-date total return as of September 30, 2012 was 0.01%.&lt;br /&gt; &lt;br /&gt;High Quarter 9/30/07 1.24%&lt;br /&gt; &lt;br /&gt;Low Quarter 6/30/09 0.00%&lt;/tt&gt;</rr:BarChartClosingTextBlock>
  <rr:OperatingExpensesCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_6">Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)</rr:OperatingExpensesCaption>
  <rr:AverageAnnualReturnCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_51">Average Annual Total Returns (as of December 31, 2011)</rr:AverageAnnualReturnCaption>
  <rr:RiskMoneyMarketFund contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_24">Although the Fund seeks to preserve the value of your investment at $1.00 per share,
if it is unable to do so, it is possible to lose money by investing in the Fund.</rr:RiskMoneyMarketFund>
  <rr:RiskNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_23">&lt;tt&gt;There is no assurance that the Fund will achieve its investment objectives.&lt;br /&gt;Although the Fund seeks to preserve the value of your investment at $1.00 per&lt;br /&gt;share, if it is unable to do so, it is possible to lose money by investing in&lt;br /&gt;the Fund. The principal risks of investing in the Fund include:&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Credit and Interest Rate Risk. Debt obligations, such as bonds, are subject &lt;br /&gt;&amp;#xA0;&amp;#xA0;to two types of risk: credit and interest rate risk. Credit risk refers to &lt;br /&gt;&amp;#xA0;&amp;#xA0;the possibility that the issuer of a security will be unable to make interest&lt;br /&gt;&amp;#xA0;&amp;#xA0;payments and/or repay the principal on its debt. Interest rate risk refers to&lt;br /&gt;&amp;#xA0;&amp;#xA0;fluctuations in the value of a debt security resulting from changes in the&lt;br /&gt;&amp;#xA0;&amp;#xA0;general level of interest rates.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; U.S. Government Securities. With respect to U.S. government securities that&lt;br /&gt;&amp;#xA0;&amp;#xA0;are not backed by the full faith and credit of the United States, there is the&lt;br /&gt;&amp;#xA0;&amp;#xA0;risk that the U.S. Government will not provide financial support to such U.S.&lt;br /&gt;&amp;#xA0;&amp;#xA0;government agencies, instrumentalities or sponsored enterprises if it is not&lt;br /&gt;&amp;#xA0;&amp;#xA0;obligated to do so by law.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Asset-Backed Securities. Asset-backed securities involve the risk that the&lt;br /&gt;&amp;#xA0;&amp;#xA0;various federal and state consumer laws and other legal and economic factors &lt;br /&gt;&amp;#xA0;&amp;#xA0;may result in the collateral backing the securities being insufficient to &lt;br /&gt;&amp;#xA0;&amp;#xA0;support payment on the securities. Some asset-backed securities also entail &lt;br /&gt;&amp;#xA0;&amp;#xA0;prepayment risk, which may vary depending on the type of asset.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Foreign Money Market Securities. Investing in money market securities of&lt;br /&gt;&amp;#xA0;&amp;#xA0;foreign issuers involves some additional risks, including the possibility of&lt;br /&gt;&amp;#xA0;&amp;#xA0;adverse political, economic or other developments affecting the issuers of &lt;br /&gt;&amp;#xA0;&amp;#xA0;these securities.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Repurchase Agreements. Repurchase agreements are subject to risks associated&lt;br /&gt;&amp;#xA0;&amp;#xA0;with the possibility of default by the seller at a time when the collateral has&lt;br /&gt;&amp;#xA0;&amp;#xA0;declined in value, or insolvency of the seller, which may affect the Fund&apos;s&lt;br /&gt;&amp;#xA0;&amp;#xA0;right to control the collateral and result in certain costs and delays.&lt;br /&gt; &lt;br /&gt;Shares of the Fund are not bank deposits and are not guaranteed or insured by&lt;br /&gt;the FDIC or any other government agency.&lt;/tt&gt;</rr:RiskNarrativeTextBlock>
  <rr:ExpenseHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_4">Fees and Expenses</rr:ExpenseHeading>
  <rr:StrategyHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_20">Principal Investment Strategies</rr:StrategyHeading>
  <rr:PerformanceNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_27">&lt;tt&gt;The bar chart and table below provide some indication of the risks of investing&lt;br /&gt;in the Fund by showing changes in the Fund&apos;s performance from year to year and&lt;br /&gt;by showing the Fund&apos;s average annual returns for the one, five and 10 year&lt;br /&gt;periods. The Fund&apos;s past performance does not indicate how the Fund will perform&lt;br /&gt;in the future.&lt;/tt&gt;</rr:PerformanceNarrativeTextBlock>
  <rr:ExpenseNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_5">&lt;tt&gt;The table below describes the fees and expenses that you may pay if you buy and&lt;br /&gt;hold shares of the Fund. The Fund is a no-load fund. The Fund does not impose&lt;br /&gt;any sales charges.&lt;/tt&gt;</rr:ExpenseNarrativeTextBlock>
  <rr:AnnualFundOperatingExpensesTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_59">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/OperatingExpensesData_S000004050Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:AnnualFundOperatingExpensesTableTextBlock>
  <rr:PerformanceTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_60">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/PerformanceTableData_S000004050Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:PerformanceTableTextBlock>
  <rr:RiskNotInsuredDepositoryInstitution contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_25">Shares of the Fund are not bank deposits and are not guaranteed or insured by the FDIC or any other government agency.</rr:RiskNotInsuredDepositoryInstitution>
  <rr:MoneyMarketSevenDayYieldPhone contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1001_55">(800) 869-NEWS</rr:MoneyMarketSevenDayYieldPhone>
  <dei:TradingSymbol contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_0">AAMXX</dei:TradingSymbol>
  <rr:AnnualReturn2002 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_31">0.0146</rr:AnnualReturn2002>
  <rr:LowestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_47">Low Quarter</rr:LowestQuarterlyReturnLabel>
  <rr:HighestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_44">High Quarter</rr:HighestQuarterlyReturnLabel>
  <rr:BarChartYearToDateReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_43">2012-09-30</rr:BarChartYearToDateReturnDate>
  <rr:ExpenseExampleYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="iso4217_USD" decimals="0" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_16">24</rr:ExpenseExampleYear01>
  <rr:BarChartHighestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_46">2007-09-30</rr:BarChartHighestQuarterlyReturnDate>
  <rr:ExpenseExampleYear03 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="iso4217_USD" decimals="0" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_17">74</rr:ExpenseExampleYear03>
  <rr:BarChartLowestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_48">0.0000</rr:BarChartLowestQuarterlyReturn>
  <rr:AnnualReturn2004 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_33">0.0099</rr:AnnualReturn2004>
  <rr:FeeWaiverOrReimbursementOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_11">-0.0019</rr:FeeWaiverOrReimbursementOverAssets>
  <rr:AnnualReturn2010 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_39">0.0001</rr:AnnualReturn2010>
  <rr:ExpenseExampleYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="iso4217_USD" decimals="0" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_19">293</rr:ExpenseExampleYear10>
  <rr:ExpenseExampleYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="iso4217_USD" decimals="0" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_18">130</rr:ExpenseExampleYear05>
  <rr:AnnualReturn2007 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_36">0.0501</rr:AnnualReturn2007>
  <rr:BarChartHighestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_45">0.0124</rr:BarChartHighestQuarterlyReturn>
  <rr:AverageAnnualReturnYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_52">0.0001</rr:AverageAnnualReturnYear01>
  <rr:OtherExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_9">0.0008</rr:OtherExpensesOverAssets>
  <rr:AnnualReturn2008 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_37">0.0263</rr:AnnualReturn2008>
  <rr:ManagementFeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_7">0.0024</rr:ManagementFeesOverAssets>
  <rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_12">These fee waivers and/or expense reimbursements will continue for at least one year
or until such time as the Fund&apos;s Board of Trustees acts to discontinue all or a portion
of such waivers and/or expense reimbursements when it deems such action appropriate.</rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
  <rr:BarChartLowestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_49">2009-06-30</rr:BarChartLowestQuarterlyReturnDate>
  <rr:AnnualReturn2009 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_38">0.0003</rr:AnnualReturn2009>
  <rr:AverageAnnualReturnYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_53">0.0152</rr:AverageAnnualReturnYear05>
  <rr:AnnualReturn2005 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_34">0.0285</rr:AnnualReturn2005>
  <rr:YearToDateReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_41">The year-to-date total return</rr:YearToDateReturnLabel>
  <rr:AnnualReturn2011 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_40">0.0001</rr:AnnualReturn2011>
  <rr:AnnualReturn2003 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_32">0.0078</rr:AnnualReturn2003>
  <rr:DistributionAndService12b1FeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_8">0.0010</rr:DistributionAndService12b1FeesOverAssets>
  <rr:AverageAnnualReturnYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_54">0.0183</rr:AverageAnnualReturnYear10>
  <rr:NetExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_13">0.0023</rr:NetExpensesOverAssets>
  <rr:ExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_10">0.0042</rr:ExpensesOverAssets>
  <rr:AnnualReturn2006 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_35">0.0468</rr:AnnualReturn2006>
  <rr:BarChartYearToDateReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980216_602238x-9980212_602488x-9980221" unitRef="pure" decimals="4" id="id_399924_8C3A6914-88EB-4EFB-A16D-FD6BB4C42278_1002_42">0.0001</rr:BarChartYearToDateReturn>
  <rr:ExpenseExampleWithRedemptionTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_58">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/ExpenseExample_S000004040Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:ExpenseExampleWithRedemptionTableTextBlock>
  <rr:BarChartTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_57">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/BarChartData_S000004040Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:BarChartTableTextBlock>
  <rr:ObjectivePrimaryTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_3">&lt;tt&gt;Active Assets Government Securities Trust is a money market fund that seeks to&lt;br /&gt;provide high current income, preservation of capital and liquidity.&lt;/tt&gt;</rr:ObjectivePrimaryTextBlock>
  <rr:ExpenseExampleNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_15">&lt;tt&gt;The example below is intended to help you compare the cost of investing in the&lt;br /&gt;Fund with the cost of investing in other mutual funds.&lt;br /&gt; &lt;br /&gt;The example assumes that you invest $10,000 in the Fund, your investment has a&lt;br /&gt;5% return each year, and the Fund&apos;s operating expenses remain the same. Although&lt;br /&gt;your actual costs may be higher or lower, based on these assumptions your costs&lt;br /&gt;would be:&lt;/tt&gt;</rr:ExpenseExampleNarrativeTextBlock>
  <rr:StrategyNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_21">&lt;tt&gt;The Fund invests in high quality, short-term U.S. government securities. In&lt;br /&gt;selecting investments, the Adviser and/or Morgan Stanley Investment Management&lt;br /&gt;Limited ("Sub-Adviser") seek to maintain the Fund&apos;s share price at $1.00. The&lt;br /&gt;U.S. government securities that the Fund may purchase include: U.S Treasury&lt;br /&gt;bills, notes and bonds, all of which are direct obligations of the U.S.&lt;br /&gt;Government; securities issued by agencies and instrumentalities of the U.S.&lt;br /&gt;Government, which are backed by the full faith and credit of the United States;&lt;br /&gt;securities issued by agencies and instrumentalities which are not backed by the&lt;br /&gt;full faith and credit of the United States, but whose issuing agency or&lt;br /&gt;instrumentality has the right to borrow from the U.S. Treasury to meet its&lt;br /&gt;obligations; securities issued by agencies and instrumentalities which are&lt;br /&gt;backed solely by the credit of the issuing agency or instrumentality; and&lt;br /&gt;securities guaranteed under the FDIC Temporary Liquidity Guarantee Program. &lt;br /&gt;The Fund also may invest up to 10% of its assets in FDIC insured certificates &lt;br /&gt;of deposit of banks and savings and loan institutions. In addition, the Fund &lt;br /&gt;may invest in repurchase agreements.&lt;/tt&gt;</rr:StrategyNarrativeTextBlock>
  <rr:RiskReturnHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_1">Active Assets Government Securities Trust</rr:RiskReturnHeading>
  <rr:ExpenseExampleHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_14">Example</rr:ExpenseExampleHeading>
  <rr:ObjectiveHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_2">Investment Objectives</rr:ObjectiveHeading>
  <rr:PerformancePastDoesNotIndicateFuture contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_29">The Fund&apos;s past performance does not indicate how the Fund will perform in the future.</rr:PerformancePastDoesNotIndicateFuture>
  <rr:RiskHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_22">Principal Risks</rr:RiskHeading>
  <rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_12">These fee waivers and/or expense reimbursements will continue for at least one
year or until such time as the Fund&apos;s Board of Trustees acts to discontinue all
or a portion of such waivers and/or expense reimbursements when it deems such
action appropriate.</rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
  <rr:BarChartHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_30">Annual Total Returns--Calendar Years</rr:BarChartHeading>
  <rr:BarChartAndPerformanceTableHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_26">Past Performance</rr:BarChartAndPerformanceTableHeading>
  <rr:PerformanceTableClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_56">&lt;tt&gt;For the Fund&apos;s most recent 7-day annualized yield you may call toll-free (800)&lt;br /&gt;869-NEWS.&lt;/tt&gt;</rr:PerformanceTableClosingTextBlock>
  <rr:PerformanceInformationIllustratesVariabilityOfReturns contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_28">The bar chart and table below provide some indication of the risks of investing
in the Fund by showing changes in the Fund&apos;s performance from year to year and by
showing the Fund&apos;s average annual returns for the one, five and 10 year periods.</rr:PerformanceInformationIllustratesVariabilityOfReturns>
  <rr:BarChartClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_50">&lt;tt&gt;The year-to-date total return as of September 30, 2012 was 0.01%.&lt;br /&gt; &lt;br /&gt;High Quarter 9/30/06 1.16%&lt;br /&gt; &lt;br /&gt;Low Quarter 6/30/09 0.00%&lt;/tt&gt;</rr:BarChartClosingTextBlock>
  <rr:OperatingExpensesCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_6">Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)</rr:OperatingExpensesCaption>
  <rr:AverageAnnualReturnCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_51">Average Annual Total Returns (as of December 31, 2011)</rr:AverageAnnualReturnCaption>
  <rr:RiskMoneyMarketFund contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_24">Although the Fund seeks to preserve the value of your investment at $1.00 per share,
if it is unable to do so, it is possible to lose money by investing in the Fund.</rr:RiskMoneyMarketFund>
  <rr:RiskNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_23">&lt;tt&gt;There is no assurance that the Fund will achieve its investment objectives.&lt;br /&gt;Although the Fund seeks to preserve the value of your investment at $1.00 per&lt;br /&gt;share, if it is unable to do so, it is possible to lose money by investing in&lt;br /&gt;the Fund. The principal risks of investing in the Fund include:&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Credit and Interest Rate Risk. Debt obligations, such as bonds, are subject to&lt;br /&gt;&amp;#xA0;&amp;#xA0;two types of risk: credit risk and interest rate risk. Credit risk refers to the&lt;br /&gt;&amp;#xA0;&amp;#xA0;possibility that the issuer of a security will be unable to make interest payments &lt;br /&gt;&amp;#xA0;&amp;#xA0;and/or repay the principal on its debt. Interest rate risk refers to fluctuations &lt;br /&gt;&amp;#xA0;&amp;#xA0;in the value of a debt security resulting from changes in the general level of &lt;br /&gt;&amp;#xA0;&amp;#xA0;interest rates.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; U.S. Government Securities. With respect to U.S. government securities that&lt;br /&gt;&amp;#xA0;&amp;#xA0;are not backed by the full faith and credit of the United States, there is the&lt;br /&gt;&amp;#xA0;&amp;#xA0;risk that the U.S. Government will not provide financial support to such U.S.&lt;br /&gt;&amp;#xA0;&amp;#xA0;government agencies, instrumentalities or sponsored enterprises if it is not&lt;br /&gt;&amp;#xA0;&amp;#xA0;obligated to do so by law.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Repurchase Agreements. Repurchase agreements are subject to risks associated&lt;br /&gt;&amp;#xA0;&amp;#xA0;with the possibility of default by the seller at a time when the collateral &lt;br /&gt;&amp;#xA0;&amp;#xA0;has declined in value, or insolvency of the seller, which may affect the Fund&apos;s&lt;br /&gt;&amp;#xA0;&amp;#xA0;right to control the collateral and result in certain costs and delays.&lt;br /&gt; &lt;br /&gt;Shares of the Fund are not bank deposits and are not guaranteed or insured by&lt;br /&gt;the FDIC or any other government agency.&lt;/tt&gt;</rr:RiskNarrativeTextBlock>
  <rr:ExpenseHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_4">Fees and Expenses</rr:ExpenseHeading>
  <rr:StrategyHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_20">Principal Investment Strategies</rr:StrategyHeading>
  <rr:PerformanceNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_27">&lt;tt&gt;The bar chart and table below provide some indication of the risks of investing&lt;br /&gt;in the Fund by showing changes in the Fund&apos;s performance from year to year and&lt;br /&gt;by showing the Fund&apos;s average annual returns for the one, five and 10 year&lt;br /&gt;periods. The Fund&apos;s past performance does not indicate how the Fund will perform&lt;br /&gt;in the future.&lt;/tt&gt;</rr:PerformanceNarrativeTextBlock>
  <rr:ExpenseNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_5">&lt;tt&gt;The table below describes the fees and expenses that you may pay if you buy and&lt;br /&gt;hold shares of the Fund. The Fund is a no-load fund. The Fund does not impose&lt;br /&gt;any sales charges.&lt;/tt&gt;</rr:ExpenseNarrativeTextBlock>
  <rr:AnnualFundOperatingExpensesTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_59">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/OperatingExpensesData_S000004040Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:AnnualFundOperatingExpensesTableTextBlock>
  <rr:PerformanceTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_60">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/PerformanceTableData_S000004040Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:PerformanceTableTextBlock>
  <rr:RiskNotInsuredDepositoryInstitution contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_25">Shares of the Fund are not bank deposits and are not guaranteed or insured by the FDIC or any other government agency.</rr:RiskNotInsuredDepositoryInstitution>
  <rr:MoneyMarketSevenDayYieldPhone contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1001_55">(800) 869-NEWS</rr:MoneyMarketSevenDayYieldPhone>
  <dei:TradingSymbol contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_0">AAGXX</dei:TradingSymbol>
  <rr:AnnualReturn2002 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_31">0.0125</rr:AnnualReturn2002>
  <rr:LowestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_47">Low Quarter</rr:LowestQuarterlyReturnLabel>
  <rr:HighestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_44">High Quarter</rr:HighestQuarterlyReturnLabel>
  <rr:BarChartYearToDateReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_43">2012-09-30</rr:BarChartYearToDateReturnDate>
  <rr:ExpenseExampleYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="iso4217_USD" decimals="0" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_16">11</rr:ExpenseExampleYear01>
  <rr:BarChartHighestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_46">2006-09-30</rr:BarChartHighestQuarterlyReturnDate>
  <rr:ExpenseExampleYear03 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="iso4217_USD" decimals="0" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_17">35</rr:ExpenseExampleYear03>
  <rr:BarChartLowestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_48">0.0000</rr:BarChartLowestQuarterlyReturn>
  <rr:AnnualReturn2004 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_33">0.0079</rr:AnnualReturn2004>
  <rr:FeeWaiverOrReimbursementOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_11">-0.0059</rr:FeeWaiverOrReimbursementOverAssets>
  <rr:AnnualReturn2010 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_39">0.0001</rr:AnnualReturn2010>
  <rr:ExpenseExampleYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="iso4217_USD" decimals="0" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_19">141</rr:ExpenseExampleYear10>
  <rr:ExpenseExampleYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="iso4217_USD" decimals="0" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_18">62</rr:ExpenseExampleYear05>
  <rr:AnnualReturn2007 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_36">0.0464</rr:AnnualReturn2007>
  <rr:BarChartHighestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_45">0.0116</rr:BarChartHighestQuarterlyReturn>
  <rr:AverageAnnualReturnYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_52">0.0001</rr:AverageAnnualReturnYear01>
  <rr:OtherExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_9">0.0015</rr:OtherExpensesOverAssets>
  <rr:AnnualReturn2008 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_37">0.0199</rr:AnnualReturn2008>
  <rr:ManagementFeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_7">0.0045</rr:ManagementFeesOverAssets>
  <rr:BarChartLowestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_49">2009-06-30</rr:BarChartLowestQuarterlyReturnDate>
  <rr:AnnualReturn2009 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_38">0.0001</rr:AnnualReturn2009>
  <rr:AverageAnnualReturnYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_53">0.0132</rr:AverageAnnualReturnYear05>
  <rr:AnnualReturn2005 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_34">0.0263</rr:AnnualReturn2005>
  <rr:YearToDateReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_41">The year-to-date total return</rr:YearToDateReturnLabel>
  <rr:AnnualReturn2011 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_40">0.0001</rr:AnnualReturn2011>
  <rr:AnnualReturn2003 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_32">0.0060</rr:AnnualReturn2003>
  <rr:DistributionAndService12b1FeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_8">0.0010</rr:DistributionAndService12b1FeesOverAssets>
  <rr:AverageAnnualReturnYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_54">0.0162</rr:AverageAnnualReturnYear10>
  <rr:NetExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_13">0.0011</rr:NetExpensesOverAssets>
  <rr:ExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_10">0.0070</rr:ExpensesOverAssets>
  <rr:AnnualReturn2006 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_35">0.0439</rr:AnnualReturn2006>
  <rr:BarChartYearToDateReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980217_602238x-9980213_602488x-9980222" unitRef="pure" decimals="4" id="id_399924_58B8FB1E-8538-47E1-89F9-A26B39BD581D_1002_42">0.0001</rr:BarChartYearToDateReturn>
  <rr:ExpenseExampleWithRedemptionTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_58">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/ExpenseExample_S000004036Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:ExpenseExampleWithRedemptionTableTextBlock>
  <rr:BarChartTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_57">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/BarChartData_S000004036Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:BarChartTableTextBlock>
  <rr:ObjectivePrimaryTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_3">&lt;tt&gt;Active Assets California Tax-Free Trust is a money market fund that seeks to&lt;br /&gt;provide as high a level of daily income exempt from federal and California&lt;br /&gt;personal income tax as is consistent with stability of principal and liquidity.&lt;/tt&gt;</rr:ObjectivePrimaryTextBlock>
  <rr:ExpenseExampleNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_15">&lt;tt&gt;The example below is intended to help you compare the cost of investing in the&lt;br /&gt;Fund with the cost of investing in other mutual funds.&lt;br /&gt; &lt;br /&gt;The example assumes that you invest $10,000 in the Fund, your investment has a&lt;br /&gt;5% return each year, and the Fund&apos;s operating expenses remain the same. Although&lt;br /&gt;your actual costs may be higher or lower, based on these assumptions your costs&lt;br /&gt;would be:&lt;/tt&gt;</rr:ExpenseExampleNarrativeTextBlock>
  <rr:StrategyNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_21">&lt;tt&gt;The Fund will invest in high quality, short-term securities that are normally&lt;br /&gt;municipal obligations that pay interest exempt from federal and California&lt;br /&gt;personal income taxes. The Adviser seeks to maintain the Fund&apos;s share price &lt;br /&gt;at$1.00. The Adviser generally invests substantially all of the Fund&apos;s assets &lt;br /&gt;in California municipal obligations and the Fund has a fundamental policy of&lt;br /&gt;investing at least 80% of its net assets in securities the interest on which &lt;br /&gt;is exempt from federal and California personal income tax. This policy may not &lt;br /&gt;be changed without shareholder approval. In addition, the Fund may invest up &lt;br /&gt;to 20% of its net assets in securities that pay interest income subject to the&lt;br /&gt;"alternative minimum tax," and some taxpayers may have to pay tax on a Fund&lt;br /&gt;distribution of this income. For more information, see the "Tax Consequences"&lt;br /&gt;section beginning on page 26 of this Prospectus.&lt;br /&gt; &lt;br /&gt;Municipal obligations are securities issued by state and local governments and&lt;br /&gt;their agencies. These securities typically are "general obligation" or "revenue"&lt;br /&gt;bonds, notes or commercial paper, including participations in lease obligations&lt;br /&gt;and installment purchase contracts of municipalities.&lt;br /&gt; &lt;br /&gt;The Fund may purchase debt obligations that have fixed, variable or floating&lt;br /&gt;rates of interest. The interest rates payable on variable or floating rate&lt;br /&gt;obligations may fluctuate based upon changes in market rates.&lt;br /&gt; &lt;br /&gt;The Fund&apos;s investments may include tender option bonds and custodial receipts.&lt;br /&gt;Tender option bonds are municipal obligations held pursuant to a custodial&lt;br /&gt;arrangement and issued pursuant to an agreement with a third-party such as &lt;br /&gt;a bank or financial institution to provide the holder with the option of &lt;br /&gt;tendering the bond at periodic intervals. The holder of the tender option &lt;br /&gt;bond effectively holds a demand obligation that bears interest at prevailing &lt;br /&gt;short-term rates. Custodial receipts represent interests in future interest &lt;br /&gt;and/or principal payments on U.S. government securities or municipal obligations. &lt;br /&gt;Additionally, the Fund may invest in investment companies, including money market &lt;br /&gt;funds some or all of which may be advised or managed by the Adviser or its &lt;br /&gt;affiliates.&lt;/tt&gt;</rr:StrategyNarrativeTextBlock>
  <rr:RiskReturnHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_1">Active Assets California Tax-Free Trust</rr:RiskReturnHeading>
  <rr:ExpenseExampleHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_14">Example</rr:ExpenseExampleHeading>
  <rr:ObjectiveHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_2">Investment Objective</rr:ObjectiveHeading>
  <rr:PerformancePastDoesNotIndicateFuture contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_29">The Fund&apos;s past performance does not indicate how the Fund will perform in the future.</rr:PerformancePastDoesNotIndicateFuture>
  <rr:RiskHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_22">Principal Risks</rr:RiskHeading>
  <rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_12">These fee waivers and/or expense reimbursements will continue for at least one
year or until such time as the Fund&apos;s Board of Trustees acts to discontinue all
or a portion of such waivers and/or expense reimbursements when it deems such
action appropriate.</rr:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
  <rr:BarChartHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_30">Annual Total Returns--Calendar Years</rr:BarChartHeading>
  <rr:BarChartAndPerformanceTableHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_26">Past Performance</rr:BarChartAndPerformanceTableHeading>
  <rr:PerformanceTableClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_56">&lt;tt&gt;For the Fund&apos;s most recent 7-day annualized yield you may call toll-free (800)&lt;br /&gt;869-NEWS.&lt;/tt&gt;</rr:PerformanceTableClosingTextBlock>
  <rr:PerformanceInformationIllustratesVariabilityOfReturns contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_28">The bar chart and table below provide some indication of the risks of investing in
the Fund by showing changes in the Fund&apos;s performance from year to year and by showing
the Fund&apos;s average annual returns for the one, five and 10 year periods.</rr:PerformanceInformationIllustratesVariabilityOfReturns>
  <rr:BarChartClosingTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_50">&lt;tt&gt;The year-to-date total return as of September 30, 2012 was 0.01%.&lt;br /&gt; &lt;br /&gt;High Quarter 6/30/07 0.79%&lt;br /&gt; &lt;br /&gt;Low Quarter 6/30/09 0.00%&lt;/tt&gt;</rr:BarChartClosingTextBlock>
  <rr:OperatingExpensesCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_6">Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)</rr:OperatingExpensesCaption>
  <rr:AverageAnnualReturnCaption contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_51">Average Annual Total Returns (as of December 31, 2011)</rr:AverageAnnualReturnCaption>
  <rr:RiskMoneyMarketFund contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_24">Although the Fund seeks to preserve the value of your investment at $1.00 per share,
if it is unable to do so, it is possible to lose money by investing in the Fund.</rr:RiskMoneyMarketFund>
  <rr:RiskNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_23">&lt;tt&gt;There is no assurance that the Fund will achieve its investment objectives.&lt;br /&gt;Although the Fund seeks to preserve the value of your investment at $1.00 per&lt;br /&gt;share, if it is unable to do so, it is possible to lose money by investing in&lt;br /&gt;the Fund. The principal risks of investing in the Fund include:&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Credit and Interest Rate Risk. Debt obligations, such as bonds, are subject &lt;br /&gt;&amp;#xA0;&amp;#xA0;to two types of risk: credit risk and interest rate risk. Credit risk refers &lt;br /&gt;&amp;#xA0;&amp;#xA0;to the possibility that the issuer of a security will be unable to make interest&lt;br /&gt;&amp;#xA0;&amp;#xA0;payments and/or repay the principal on its debt. In the case of revenue bonds,&lt;br /&gt;&amp;#xA0;&amp;#xA0;notes or commercial paper, for example, the credit risk is the possibility that&lt;br /&gt;&amp;#xA0;&amp;#xA0;the user fees from a project or other specified revenue sources are insufficient&lt;br /&gt;&amp;#xA0;&amp;#xA0;to meet interest and/or principal payment obligations. Interest rate risk refers&lt;br /&gt;&amp;#xA0;&amp;#xA0;to fluctuations in the value of a debt security resulting from changes in the&lt;br /&gt;&amp;#xA0;&amp;#xA0;general level of interest rates.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Tender Option Bonds and Custodial Receipts. The risks of tender option bonds&lt;br /&gt;&amp;#xA0;&amp;#xA0;and custodial receipts include the risk that the owner of such instruments may&lt;br /&gt;&amp;#xA0;&amp;#xA0;not be considered the owner for federal income tax purposes and thus will not be&lt;br /&gt;&amp;#xA0;&amp;#xA0;entitled to treat such interest as exempt from federal income tax. Additionally,&lt;br /&gt;&amp;#xA0;&amp;#xA0;the occurrence of certain defaults or a credit rating downgrade on the underlying &lt;br /&gt;&amp;#xA0;&amp;#xA0;security may impair the ability to tender the bond or receipt back to the &lt;br /&gt;&amp;#xA0;&amp;#xA0;third-party provider of the demand option, thus causing the bond or receipt&lt;br /&gt;&amp;#xA0;&amp;#xA0;to become illiquid.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; Investment Companies. An investment in an investment company is subject to the&lt;br /&gt;&amp;#xA0;&amp;#xA0;underlying risks of that investment company&apos;s portfolio securities. In addition&lt;br /&gt;&amp;#xA0;&amp;#xA0;to the Fund&apos;s fees and expenses, the Fund generally would bear its share of the&lt;br /&gt;&amp;#xA0;&amp;#xA0;investment company&apos;s fees and expenses.&lt;br /&gt; &lt;br /&gt;&amp;#x2022; California Municipal Securities Risks. As the Fund invests principally in&lt;br /&gt;&amp;#xA0;&amp;#xA0;municipal obligations issued by state and local governments and their agencies,&lt;br /&gt;&amp;#xA0;&amp;#xA0;the Fund is susceptible to political, economic, or other factors affecting&lt;br /&gt;&amp;#xA0;&amp;#xA0;issuers of California municipal obligations. The deterioration of California&apos;s&lt;br /&gt;&amp;#xA0;&amp;#xA0;fiscal situation as a result of recent economic conditions increases the risk &lt;br /&gt;&amp;#xA0;&amp;#xA0;of investing in California municipal securities. Several major ratings agencies&lt;br /&gt;&amp;#xA0;&amp;#xA0;have downgraded California&apos;s general obligation bond rating in recent years. A&lt;br /&gt;&amp;#xA0;&amp;#xA0;default or credit rating downgrade of a small number of California municipal&lt;br /&gt;&amp;#xA0;&amp;#xA0;security issuers could affect the market values and marketability of all&lt;br /&gt;&amp;#xA0;&amp;#xA0;California municipal obligations held by the Fund and the Fund&apos;s performance.&lt;br /&gt; &lt;br /&gt;Shares of the Fund are not bank deposits and are not guaranteed or insured by&lt;br /&gt;the FDIC or any other government agency.&lt;/tt&gt;</rr:RiskNarrativeTextBlock>
  <rr:ExpenseHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_4">Fees and Expenses</rr:ExpenseHeading>
  <rr:StrategyHeading contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_20">Principal Investment Strategies</rr:StrategyHeading>
  <rr:PerformanceNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_27">&lt;tt&gt;The bar chart and table below provide some indication of the risks of investing&lt;br /&gt;in the Fund by showing changes in the Fund&apos;s performance from year to year and&lt;br /&gt;by showing the Fund&apos;s average annual returns for the one, five and 10 year&lt;br /&gt;periods. The Fund&apos;s past performance does not indicate how the Fund will perform&lt;br /&gt;in the future.&lt;/tt&gt;</rr:PerformanceNarrativeTextBlock>
  <rr:ExpenseNarrativeTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_5">&lt;tt&gt;The table below describes the fees and expenses that you may pay if you buy and&lt;br /&gt;hold shares of the Fund. The Fund is a no-load fund. The Fund does not impose&lt;br /&gt;any sales charges.&lt;/tt&gt;</rr:ExpenseNarrativeTextBlock>
  <rr:AnnualFundOperatingExpensesTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_59">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/OperatingExpensesData_S000004036Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:AnnualFundOperatingExpensesTableTextBlock>
  <rr:PerformanceTableTextBlock contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_60">&lt;div style="display:none"&gt;~ http://www.morganstanley.com/role/PerformanceTableData_S000004036Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact *  ~&lt;/div&gt;</rr:PerformanceTableTextBlock>
  <rr:RiskNotInsuredDepositoryInstitution contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_25">Shares of the Fund are not bank deposits and are not guaranteed or insured by the FDIC or any other government agency.</rr:RiskNotInsuredDepositoryInstitution>
  <rr:MoneyMarketSevenDayYieldPhone contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1001_55">(800) 869-NEWS</rr:MoneyMarketSevenDayYieldPhone>
  <dei:TradingSymbol contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_0">AACXX</dei:TradingSymbol>
  <rr:AnnualReturn2002 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_31">0.0080</rr:AnnualReturn2002>
  <rr:LowestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_47">Low Quarter</rr:LowestQuarterlyReturnLabel>
  <rr:HighestQuarterlyReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_44">High Quarter</rr:HighestQuarterlyReturnLabel>
  <rr:BarChartYearToDateReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_43">2012-09-30</rr:BarChartYearToDateReturnDate>
  <rr:ExpenseExampleYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="iso4217_USD" decimals="0" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_16">14</rr:ExpenseExampleYear01>
  <rr:BarChartHighestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_46">2007-06-30</rr:BarChartHighestQuarterlyReturnDate>
  <rr:ExpenseExampleYear03 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="iso4217_USD" decimals="0" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_17">45</rr:ExpenseExampleYear03>
  <rr:BarChartLowestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_48">0.0000</rr:BarChartLowestQuarterlyReturn>
  <rr:AnnualReturn2004 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_33">0.0060</rr:AnnualReturn2004>
  <rr:FeeWaiverOrReimbursementOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_11">-0.0036</rr:FeeWaiverOrReimbursementOverAssets>
  <rr:AnnualReturn2010 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_39">0.0001</rr:AnnualReturn2010>
  <rr:ExpenseExampleYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="iso4217_USD" decimals="0" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_19">179</rr:ExpenseExampleYear10>
  <rr:ExpenseExampleYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="iso4217_USD" decimals="0" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_18">79</rr:ExpenseExampleYear05>
  <rr:AnnualReturn2007 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_36">0.0310</rr:AnnualReturn2007>
  <rr:BarChartHighestQuarterlyReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_45">0.0079</rr:BarChartHighestQuarterlyReturn>
  <rr:AverageAnnualReturnYear01 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_52">0.0001</rr:AverageAnnualReturnYear01>
  <rr:OtherExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_9">0.0007</rr:OtherExpensesOverAssets>
  <rr:AnnualReturn2008 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_37">0.0155</rr:AnnualReturn2008>
  <rr:ManagementFeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_7">0.0033</rr:ManagementFeesOverAssets>
  <rr:BarChartLowestQuarterlyReturnDate contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_49">2009-06-30</rr:BarChartLowestQuarterlyReturnDate>
  <rr:AnnualReturn2009 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_38">0.0002</rr:AnnualReturn2009>
  <rr:AverageAnnualReturnYear05 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_53">0.0093</rr:AverageAnnualReturnYear05>
  <rr:AnnualReturn2005 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_34">0.0178</rr:AnnualReturn2005>
  <rr:YearToDateReturnLabel contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_41">The year-to-date total return</rr:YearToDateReturnLabel>
  <rr:AnnualReturn2011 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_40">0.0001</rr:AnnualReturn2011>
  <rr:AnnualReturn2003 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_32">0.0041</rr:AnnualReturn2003>
  <rr:DistributionAndService12b1FeesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_8">0.0010</rr:DistributionAndService12b1FeesOverAssets>
  <rr:AverageAnnualReturnYear10 contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_54">0.0110</rr:AverageAnnualReturnYear10>
  <rr:NetExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_13">0.0014</rr:NetExpensesOverAssets>
  <rr:ExpensesOverAssets contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_10">0.0050</rr:ExpensesOverAssets>
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  <rr:BarChartYearToDateReturn contextRef="eol_0001104659-12-071642_STD_1_20121031_0_602228x-9980218_602238x-9980214_602488x-9980223" unitRef="pure" decimals="4" id="id_399924_898A2744-319F-4E08-B4FF-11622532BAC9_1002_42">0.0001</rr:BarChartYearToDateReturn>
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