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<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2026"
  xmlns:ffd="http://xbrl.sec.gov/ffd/2026"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
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  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <link:schemaRef
      xlink:href="https://xbrl.sec.gov/ffd/2026/ffd-2026.xsd"
      xlink:type="simple"/>
    <context id="rc">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001833936</identifier>
        </entity>
        <period>
            <startDate>2026-07-24</startDate>
            <endDate>2026-07-24</endDate>
        </period>
    </context>
    <context id="offrl_1">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001833936</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>1</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-07-24</startDate>
            <endDate>2026-07-24</endDate>
        </period>
    </context>
    <unit id="USD">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="Shares">
        <measure>shares</measure>
    </unit>
    <ffd:FormTp contextRef="rc" id="ixv-330">N-2</ffd:FormTp>
    <ffd:SubmissnTp contextRef="rc" id="ixv-331">N-2</ffd:SubmissnTp>
    <ffd:FeeExhibitTp contextRef="rc" id="ixv-332">EX-FILING FEES</ffd:FeeExhibitTp>
    <dei:EntityCentralIndexKey contextRef="rc" id="ixv-333">0001833936</dei:EntityCentralIndexKey>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-334">BlackRock Alpha Strategies Fund</dei:EntityRegistrantName>
    <ffd:OfferingTableNa contextRef="rc" id="hiddenrcOfferingTableNa" xsi:nil="true"/>
    <ffd:OffsetTableNa contextRef="rc" id="hiddenrcOffsetTableNa">N/A</ffd:OffsetTableNa>
    <ffd:CombinedProspectusTableNa contextRef="rc" id="hiddenrcCombinedProspectusTableNa">N/A</ffd:CombinedProspectusTableNa>
    <ffd:FormTp contextRef="rc" id="ixv-362">N-2</ffd:FormTp>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-363">BlackRock Alpha Strategies Fund</dei:EntityRegistrantName>
    <ffd:OfferingSctyTp contextRef="offrl_1" id="ixv-364">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_1" id="ixv-365">Common Shares of Beneficial Interest, $0.001 par value</ffd:OfferingSctyTitl>
    <ffd:Rule415a6Flg contextRef="offrl_1" id="ixv-366">true</ffd:Rule415a6Flg>
    <ffd:AmtSctiesRegd
      contextRef="offrl_1"
      decimals="0"
      id="ixv-367"
      unitRef="Shares">0</ffd:AmtSctiesRegd>
    <ffd:MaxAggtOfferingPric
      contextRef="offrl_1"
      decimals="2"
      id="ixv-368"
      unitRef="USD">345340000.00</ffd:MaxAggtOfferingPric>
    <ffd:CfwdFormTp contextRef="offrl_1" id="ixv-369">N-2</ffd:CfwdFormTp>
    <ffd:CfwdPrrFileNb contextRef="offrl_1" id="ixv-370">333-273507</ffd:CfwdPrrFileNb>
    <ffd:CfwdPrrFctvDt contextRef="offrl_1" id="ixv-371">2023-07-28</ffd:CfwdPrrFctvDt>
    <ffd:CfwdPrevslyPdFee
      contextRef="offrl_1"
      decimals="2"
      id="ixv-372"
      unitRef="USD">37676.59</ffd:CfwdPrevslyPdFee>
    <ffd:TtlOfferingAmt contextRef="rc" decimals="2" id="ixv-373" unitRef="USD">345340000.00</ffd:TtlOfferingAmt>
    <ffd:TtlFeeAmt contextRef="rc" decimals="2" id="ixv-374" unitRef="USD">0.00</ffd:TtlFeeAmt>
    <ffd:TtlPrevslyPdAmt contextRef="rc" decimals="2" id="ixv-375" unitRef="USD">0.00</ffd:TtlPrevslyPdAmt>
    <ffd:TtlOffsetAmt contextRef="rc" decimals="2" id="ixv-376" unitRef="USD">0.00</ffd:TtlOffsetAmt>
    <ffd:NetFeeAmt contextRef="rc" decimals="2" id="ixv-377" unitRef="USD">0.00</ffd:NetFeeAmt>
    <ffd:OfferingNote contextRef="offrl_1" id="ixv-378">Pursuant to Rule 415(a)(6) under the Securities Act of 1933, as amended (the "Securities Act"), the Registrant is carrying forward to this Registration Statement the $345,340,000 aggregate offering price of unsold shares of beneficial interest that the Registrant previously registered for sale pursuant to a registration statement on Form N-2 (File No. 333-251797) filed by the Registrant with the Securities and Exchange Commission (the "Commission") on December 29, 2020 (as amended on March 18, 2021, and declared effective on March 22, 2021, the "Original Registration Statement"), were subsequently carried forward pursuant to Rule 415(a)(6) under the Securities Act to the registration statement on Form N-2 (File No. 333-273507) filed by the Registrant with the Commission on July 28, 2023 (the "Prior Registration Statement"), and remain unsold. Filing fees have been previously paid in connection with these unsold shares of beneficial interest. Pursuant to Rule 415(a)(6) under the Securities Act, the filing fee previously paid with respect to such unsold shares of beneficial interest will continue to be applied to such unsold shares of beneficial interest. Pursuant to Rule 415(a)(6) under the Securities Act, the offering of unsold shares of beneficial interest under the Prior Registration Statement will be deemed terminated as of the date of effectiveness of this Registration Statement.</ffd:OfferingNote>
</xbrl>
