<?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>2.4.1.9</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>79</ContextCount>
  <ElementCount>87</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>37</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000001 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>020000 - Document - Risk/Return Summary {Unlabeled} - Institutional Class Prospectus - Gold and Precious Metals Fund (Institutional Class Shares, )</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInstitutionalClassProspectusGoldandPreciousMetalsFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Summary  - Institutional Class Prospectus - Gold and Precious Metals Fund (Institutional Class Shares, )</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>020006 - Disclosure - Risk/Return Detail Data {Elements} - Institutional Class Prospectus - Gold and Precious Metals Fund (Institutional Class Shares, )</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInstitutionalClassProspectusGoldandPreciousMetalsFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Detail Data  - Institutional Class Prospectus - Gold and Precious Metals Fund (Institutional Class Shares, )</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>020007 - Document - Risk/Return Summary {Unlabeled} - Institutional Class Prospectus - World Precious Minerals Fund (Institutional Class Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInstitutionalClassProspectusWorldPreciousMineralsFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Summary  - Institutional Class Prospectus - World Precious Minerals Fund (Institutional Class Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>020013 - Disclosure - Risk/Return Detail Data {Elements} - Institutional Class Prospectus - World Precious Minerals Fund (Institutional Class Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInstitutionalClassProspectusWorldPreciousMineralsFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Detail Data  - Institutional Class Prospectus - World Precious Minerals Fund (Institutional Class Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>020014 - Document - Risk/Return Summary {Unlabeled} - Institutional Class Prospectus - Global Resources Fund (Institutional Class Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInstitutionalClassProspectusGlobalResourcesFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Summary  - Institutional Class Prospectus - Global Resources Fund (Institutional Class Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>020020 - Disclosure - Risk/Return Detail Data {Elements} - Institutional Class Prospectus - Global Resources Fund (Institutional Class Shares)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInstitutionalClassProspectusGlobalResourcesFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Detail Data  - Institutional Class Prospectus - Global Resources Fund (Institutional Class Shares)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>020021 - Document - Risk/Return Summary {Unlabeled} - Institutional Class Prospectus - Emerging Europe Fund (Institutional Class Shares, )</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInstitutionalClassProspectusEmergingEuropeFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Summary  - Institutional Class Prospectus - Emerging Europe Fund (Institutional Class Shares, )</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>020027 - Disclosure - Risk/Return Detail Data {Elements} - Institutional Class Prospectus - Emerging Europe Fund (Institutional Class Shares, )</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInstitutionalClassProspectusEmergingEuropeFundInstitutionalClassShares</Role>
      <ShortName>Risk/Return Detail Data  - Institutional Class Prospectus - Emerging Europe Fund (Institutional Class Shares, )</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>020028 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - All American Equity Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusAllAmericanEquityFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - All American Equity Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>020034 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - All American Equity Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusAllAmericanEquityFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - All American Equity Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>020035 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - Holmes Macro Trends Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusHolmesMacroTrendsFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - Holmes Macro Trends Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>020041 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - Holmes Macro Trends Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusHolmesMacroTrendsFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - Holmes Macro Trends Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>020042 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - Gold and Precious Metals Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusGoldandPreciousMetalsFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - Gold and Precious Metals Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>020048 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - Gold and Precious Metals Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusGoldandPreciousMetalsFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - Gold and Precious Metals Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>020049 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - World Precious Minerals Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusWorldPreciousMineralsFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - World Precious Minerals Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>020055 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - World Precious Minerals Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusWorldPreciousMineralsFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - World Precious Minerals Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>020056 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - Global Resources Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusGlobalResourcesFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - Global Resources Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>020062 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - Global Resources Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusGlobalResourcesFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - Global Resources Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>020063 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - Emerging Europe Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusEmergingEuropeFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - Emerging Europe Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>020069 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - Emerging Europe Fund ()</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusEmergingEuropeFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - Emerging Europe Fund ()</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>020070 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - China Region Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusChinaRegionFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - China Region Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>020076 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - China Region Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusChinaRegionFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - China Region Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>020077 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - Near-Term Tax Free Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusNearTermTaxFreeFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - Near-Term Tax Free Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>020083 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - Near-Term Tax Free Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusNearTermTaxFreeFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - Near-Term Tax Free Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>020084 - Document - Risk/Return Summary {Unlabeled} - Investor Class Prospectus - U.S. Government Securities Ultra-Short Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DocumentRiskReturnSummaryUnlabeledInvestorClassProspectusUSGovernmentSecuritiesUltraShortBondFund</Role>
      <ShortName>Risk/Return Summary  - Investor Class Prospectus - U.S. Government Securities Ultra-Short Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>020090 - Disclosure - Risk/Return Detail Data {Elements} - Investor Class Prospectus - U.S. Government Securities Ultra-Short Bond Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://usglobal.com/20150430/role/DisclosureRiskReturnDetailDataElementsInvestorClassProspectusUSGovernmentSecuritiesUltraShortBondFund</Role>
      <ShortName>Risk/Return Detail Data  - Investor Class Prospectus - U.S. Government Securities Ultra-Short Bond Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.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>ck0000101507-20150430.xml</File>
    <File>ck0000101507-20150430.xsd</File>
    <File>ck0000101507-20150430_cal.xml</File>
    <File>ck0000101507-20150430_def.xml</File>
    <File>ck0000101507-20150430_lab.xml</File>
    <File>ck0000101507-20150430_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>
    <File>BarChart12.jpg</File>
    <File>BarChart13.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
