<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>13</ContextCount>
  <ElementCount>169</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>12</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report instance="agrafi-20210223.htm">
      <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.abfunds.com/role/DocumentDocumentandEntityInformationElements</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory></MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="agrafi-20210223.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>000161 - Document - Risk/Return Summary {Unlabeled} - AB Global Risk Allocation Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.abfunds.com/role/DocumentRiskReturnSummaryUnlabeledABGlobalRiskAllocationFund</Role>
      <ShortName>Risk/Return Summary- AB Global Risk Allocation Fund</ShortName>
      <MenuCategory></MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="agrafi-20210223.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>000162 - Schedule - Shareholder Fees</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.abfunds.com/role/ScheduleShareholderFees000162</Role>
      <ShortName>Shareholder Fees</ShortName>
      <MenuCategory></MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="agrafi-20210223.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>000163 - Schedule - Annual Fund Operating Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.abfunds.com/role/ScheduleAnnualFundOperatingExpenses000163</Role>
      <ShortName>Annual Fund Operating Expenses</ShortName>
      <MenuCategory></MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="agrafi-20210223.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>000164 - Schedule - Expense Example</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.abfunds.com/role/ScheduleExpenseExample000164</Role>
      <ShortName>Expense Example</ShortName>
      <MenuCategory></MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="agrafi-20210223.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>000166 - Schedule - Annual Total Returns [BarChart]</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.abfunds.com/role/ScheduleAnnualTotalReturnsBarChart000166</Role>
      <ShortName>Annual Total Returns [BarChart]</ShortName>
      <MenuCategory></MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="agrafi-20210223.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>000167 - Schedule - Average Annual Total Returns</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.abfunds.com/role/ScheduleAverageAnnualTotalReturns000167</Role>
      <ShortName>Average Annual Total Returns</ShortName>
      <MenuCategory></MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="agrafi-20210223.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>000169 - Disclosure - Risk/Return Detail Data {Elements} - AB Global Risk Allocation Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.abfunds.com/role/DisclosureRiskReturnDetailDataElementsABGlobalRiskAllocationFund</Role>
      <ShortName>Risk/Return Detail Data- AB Global Risk Allocation Fund</ShortName>
      <MenuCategory></MenuCategory>
      <Position>8</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="485BPOS" original="agrafi-20210223.htm">agrafi-20210223.htm</File>
    <File>agrafi-20210223.xsd</File>
    <File>agrafi-20210223_cal.xml</File>
    <File>agrafi-20210223_def.xml</File>
    <File>agrafi-20210223_lab.xml</File>
    <File>agrafi-20210223_pre.xml</File>
    <File>d8722263_ex99-i.htm</File>
    <File>d8729856_ex99-3.htm</File>
    <File>d8798608_ex99-j.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>g1g12c59.jpg</File>
    <File>g1g19b10.jpg</File>
    <File>g1g22c48.jpg</File>
    <File>g1g23w35.jpg</File>
    <File>g1g28b33.jpg</File>
    <File>g1g39b56.jpg</File>
    <File>g1g54a42.jpg</File>
    <File>g1g55o23.jpg</File>
    <File>g1g55p98.jpg</File>
    <File>g1g65r15.jpg</File>
    <File>g1g67z55.jpg</File>
    <File>g1g82b85.jpg</File>
    <File>g1g84v50.jpg</File>
    <File>g1g88w67.jpg</File>
    <File>image_005.jpg</File>
    <File>image_006.jpg</File>
    <File>image_007.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2020-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/rr/2018-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
