<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Version>2.4.0.8</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>23</ContextCount>
  <ElementCount>77</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>23</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000000 - Document - Document and Entity Information {Elements}</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentDocumentandEntityInformationElements</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>000011 - Document - Risk/Return Summary {Unlabeled} - Government &amp; Agency Securities Portfolio (Davidson Cash Equivalent Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledGovernmentAgencySecuritiesPortfolioDavidsonCashEquivalentShares</Role>
      <ShortName>Risk/Return Summary  - Government &amp; Agency Securities Portfolio (Davidson Cash Equivalent Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>000019 - Disclosure - Risk/Return Detail Data {Elements} - Government &amp; Agency Securities Portfolio (Davidson Cash Equivalent Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsGovernmentAgencySecuritiesPortfolioDavidsonCashEquivalentShares</Role>
      <ShortName>Risk/Return Detail Data  - Government &amp; Agency Securities Portfolio (Davidson Cash Equivalent Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>000021 - Document - Risk/Return Summary {Unlabeled} - Government &amp; Agency Securities Portfolio (Deutsche Government &amp; Agency Money Fund)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledGovernmentAgencySecuritiesPortfolioDeutscheGovernmentAgencyMoneyFund</Role>
      <ShortName>Risk/Return Summary  - Government &amp; Agency Securities Portfolio (Deutsche Government &amp; Agency Money Fund)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>000029 - Disclosure - Risk/Return Detail Data {Elements} - Government &amp; Agency Securities Portfolio (Deutsche Government &amp; Agency Money Fund)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsGovernmentAgencySecuritiesPortfolioDeutscheGovernmentAgencyMoneyFund</Role>
      <ShortName>Risk/Return Detail Data  - Government &amp; Agency Securities Portfolio (Deutsche Government &amp; Agency Money Fund)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>000031 - Document - Risk/Return Summary {Unlabeled} - Government &amp; Agency Securities Portfolio (Deutsche Government Cash Institutional Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledGovernmentAgencySecuritiesPortfolioDeutscheGovernmentCashInstitutionalShares</Role>
      <ShortName>Risk/Return Summary  - Government &amp; Agency Securities Portfolio (Deutsche Government Cash Institutional Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>000039 - Disclosure - Risk/Return Detail Data {Elements} - Government &amp; Agency Securities Portfolio (Deutsche Government Cash Institutional Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsGovernmentAgencySecuritiesPortfolioDeutscheGovernmentCashInstitutionalShares</Role>
      <ShortName>Risk/Return Detail Data  - Government &amp; Agency Securities Portfolio (Deutsche Government Cash Institutional Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>000041 - Document - Risk/Return Summary {Unlabeled} - Government &amp; Agency Securities Portfolio (Government Cash Managed Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledGovernmentAgencySecuritiesPortfolioGovernmentCashManagedShares</Role>
      <ShortName>Risk/Return Summary  - Government &amp; Agency Securities Portfolio (Government Cash Managed Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>000049 - Disclosure - Risk/Return Detail Data {Elements} - Government &amp; Agency Securities Portfolio (Government Cash Managed Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsGovernmentAgencySecuritiesPortfolioGovernmentCashManagedShares</Role>
      <ShortName>Risk/Return Detail Data  - Government &amp; Agency Securities Portfolio (Government Cash Managed Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>000051 - Document - Risk/Return Summary {Unlabeled} - Government &amp; Agency Securities Portfolio (Service Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledGovernmentAgencySecuritiesPortfolioServiceShares</Role>
      <ShortName>Risk/Return Summary  - Government &amp; Agency Securities Portfolio (Service Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>000059 - Disclosure - Risk/Return Detail Data {Elements} - Government &amp; Agency Securities Portfolio (Service Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsGovernmentAgencySecuritiesPortfolioServiceShares</Role>
      <ShortName>Risk/Return Detail Data  - Government &amp; Agency Securities Portfolio (Service Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>000061 - Document - Risk/Return Summary {Unlabeled} - Tax-Exempt Portfolio (Service Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledTaxExemptPortfolioServiceShares</Role>
      <ShortName>Risk/Return Summary  - Tax-Exempt Portfolio (Service Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>000069 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Exempt Portfolio (Service Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsTaxExemptPortfolioServiceShares</Role>
      <ShortName>Risk/Return Detail Data  - Tax-Exempt Portfolio (Service Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>000071 - Document - Risk/Return Summary {Unlabeled} - Tax-Exempt Portfolio (Deutsche Tax-Exempt Cash Institutional Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledTaxExemptPortfolioDeutscheTaxExemptCashInstitutionalShares</Role>
      <ShortName>Risk/Return Summary  - Tax-Exempt Portfolio (Deutsche Tax-Exempt Cash Institutional Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>000079 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Exempt Portfolio (Deutsche Tax-Exempt Cash Institutional Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsTaxExemptPortfolioDeutscheTaxExemptCashInstitutionalShares</Role>
      <ShortName>Risk/Return Detail Data  - Tax-Exempt Portfolio (Deutsche Tax-Exempt Cash Institutional Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>000081 - Document - Risk/Return Summary {Unlabeled} - Tax-Exempt Portfolio (Deutsche Tax-Exempt Money Fund)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledTaxExemptPortfolioDeutscheTaxExemptMoneyFund</Role>
      <ShortName>Risk/Return Summary  - Tax-Exempt Portfolio (Deutsche Tax-Exempt Money Fund)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>000089 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Exempt Portfolio (Deutsche Tax-Exempt Money Fund)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsTaxExemptPortfolioDeutscheTaxExemptMoneyFund</Role>
      <ShortName>Risk/Return Detail Data  - Tax-Exempt Portfolio (Deutsche Tax-Exempt Money Fund)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>000091 - Document - Risk/Return Summary {Unlabeled} - Tax-Exempt Portfolio (Deutsche Tax-Free Money Fund Class S)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledTaxExemptPortfolioDeutscheTaxFreeMoneyFundClassS</Role>
      <ShortName>Risk/Return Summary  - Tax-Exempt Portfolio (Deutsche Tax-Free Money Fund Class S)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>000099 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Exempt Portfolio (Deutsche Tax-Free Money Fund Class S)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsTaxExemptPortfolioDeutscheTaxFreeMoneyFundClassS</Role>
      <ShortName>Risk/Return Detail Data  - Tax-Exempt Portfolio (Deutsche Tax-Free Money Fund Class S)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>000101 - Document - Risk/Return Summary {Unlabeled} - Tax-Exempt Portfolio (Tax-Exempt Cash Managed Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledTaxExemptPortfolioTaxExemptCashManagedShares</Role>
      <ShortName>Risk/Return Summary  - Tax-Exempt Portfolio (Tax-Exempt Cash Managed Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>000109 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Exempt Portfolio (Tax-Exempt Cash Managed Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsTaxExemptPortfolioTaxExemptCashManagedShares</Role>
      <ShortName>Risk/Return Detail Data  - Tax-Exempt Portfolio (Tax-Exempt Cash Managed Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>000111 - Document - Risk/Return Summary {Unlabeled} - Tax-Exempt Portfolio (Tax-Free Investment Class)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DocumentRiskReturnSummaryUnlabeledTaxExemptPortfolioTaxFreeInvestmentClass</Role>
      <ShortName>Risk/Return Summary  - Tax-Exempt Portfolio (Tax-Free Investment Class)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>000119 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Exempt Portfolio (Tax-Free Investment Class)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.deutschefunds.com/role/DisclosureRiskReturnDetailDataElementsTaxExemptPortfolioTaxFreeInvestmentClass</Role>
      <ShortName>Risk/Return Detail Data  - Tax-Exempt Portfolio (Tax-Free Investment Class)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>040000 - Disclosure - Risk/Return Detail Data {Elements}</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/RiskReturnDetailData</Role>
      <ShortName>Risk/Return Detail Data</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs />
  <InputFiles>
    <File>cat-20140731.xml</File>
    <File>cat-20140731.xsd</File>
    <File>cat-20140731_cal.xml</File>
    <File>cat-20140731_def.xml</File>
    <File>cat-20140731_lab.xml</File>
    <File>cat-20140731_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>BarChart1.jpg</File>
    <File>BarChart2.jpg</File>
    <File>BarChart3.jpg</File>
    <File>BarChart4.jpg</File>
    <File>BarChart5.jpg</File>
    <File>BarChart6.jpg</File>
    <File>BarChart7.jpg</File>
    <File>BarChart8.jpg</File>
    <File>BarChart9.jpg</File>
    <File>BarChart10.jpg</File>
    <File>BarChart11.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
