<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="qnst-20260806.xsd" xlink:type="simple"/>
    <context id="C_8f7d9a22-7606-4f2d-b973-033a17b602db">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001117297</identifier>
        </entity>
        <period>
            <startDate>2026-08-06</startDate>
            <endDate>2026-08-06</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_f9e07961-0a1d-4d32-851d-0f6518903b79">0001117297</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_466a88ba-97bd-4ae2-a08b-99c5c536988e">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_f43c1cd7-f287-45a1-8acb-129b1c3297fa">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_7876d00f-6f26-400f-aea9-820e74e80a01">2026-08-06</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_3bfb35e9-4bfa-4bb6-b820-6b36d803ac76">QUINSTREET, INC.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_e7215c2a-0101-45d0-99b5-65ddbbee77c4">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_99cdaa7d-fb40-4ccc-9841-09960b323381">001-34628</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_6bc020f7-3e7d-44fb-b476-fb2f41b617a7">77-0512121</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_eaa6fff6-a457-4c06-9a16-5248bb1d4545">950 Tower Lane</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_03b16f21-cae6-4a79-968f-508d5429c039">12th Floor</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_e69528ef-3bfc-4bf9-818a-c8ecabf882d8">Foster City</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_b41c9045-356a-49af-a958-d9af9c520e2b">CA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_4cbb20b5-ebc9-4798-b68b-253a1bbfb93d">94404</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_a88a0c5a-4e49-4e6d-aa3e-8bd46bac0eff">650</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_fef6cd12-94f6-4ffd-bd45-bfd8ff19fd87">578-7700</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_a83ac984-1529-47d6-b2b4-92b774add581">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_f56bd1b6-10d6-47bd-b8b2-db7892e63512">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_faaab8b0-6bda-43b5-9672-cbe85c452b67">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_7ebb75c4-a850-40a3-988f-27dbd8903d34">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_5efbf2de-9f12-4905-842f-1f0a47e23550">Common Stock, par value $0.001 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_a45f17ff-727b-44c7-811b-3f6bba4d3aa5">QNST</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_89ceaac7-ffe2-4933-96f1-fec5e28db995">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="C_8f7d9a22-7606-4f2d-b973-033a17b602db"
      id="F_5d15f24d-97e5-436e-879b-e5f21e8fb2be">false</dei:EntityEmergingGrowthCompany>
</xbrl>
