<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2026"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:us-gaap="http://fasb.org/us-gaap/2026"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="ck0001726445-20260728.xsd" xlink:type="simple"/>
    <context id="C_01d0f417-5669-45a0-91d0-784ee5c1a5a1">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001726445</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementEquityComponentsAxis">us-gaap:PreferredStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-07-28</startDate>
            <endDate>2026-07-28</endDate>
        </period>
    </context>
    <context id="C_20437e1c-630e-4bd9-89d8-17a795a95f8f">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001726445</identifier>
        </entity>
        <period>
            <startDate>2026-07-28</startDate>
            <endDate>2026-07-28</endDate>
        </period>
    </context>
    <context id="C_4c81611c-51a9-4e18-94cc-43410fdf35c3">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001726445</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementEquityComponentsAxis">us-gaap:CommonStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-07-28</startDate>
            <endDate>2026-07-28</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_9ac42e3a-1d1a-4012-8797-2255b687bd8b">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_8f339555-0cf8-451c-98a7-415ac8314672">0001726445</dei:EntityCentralIndexKey>
    <dei:NoTradingSymbolFlag
      contextRef="C_01d0f417-5669-45a0-91d0-784ee5c1a5a1"
      id="F_54d3ce97-0454-493d-a953-4f2f15cef630">true</dei:NoTradingSymbolFlag>
    <dei:DocumentType
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_708df2d9-738a-4b5b-8428-9f86fd64bac7">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_79fb175d-0960-4918-8ca0-533eaaceb985">2026-07-28</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_08b75c3a-8ebb-46b6-9f84-ddc436644c5d">Seer, Inc.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_cf5be8e2-a060-46b3-a801-43ca012c5884">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_20522061-c3d9-487b-9d27-f18816d8df91">001-39747</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_45130a70-d028-44bc-a0cb-a7a1cd8ff187">82-1153150</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_58d04897-4e5f-4149-b8d8-4fbd55b09c3e">3800 Bridge Parkway</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_96f3bc0c-4f39-4a7e-8b89-cb9cf82c8d27">Suite 102</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_d80027bb-10b9-4105-8836-5efad50acad8">Redwood City</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_d6f1c012-6039-4a87-b9aa-f59d48b41d68">CA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_3b6d8f75-8b6f-447d-a000-b2da7a27f29d">94065</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_ee9ca986-5429-45c6-9401-5d6819d32469">650</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_666a4582-cf20-4202-accb-d6595ea21b83">453-0000 </dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_ffe7efc9-f675-49f7-8f48-c6798c5db708">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_2c8435b5-ea92-414b-9b24-fab3e7dbd8e0">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_96d3d8be-7627-44d2-8f22-522086ef694f">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_f1375203-ec6c-4f47-9883-eb5c43be5632">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="C_4c81611c-51a9-4e18-94cc-43410fdf35c3"
      id="F_670d1f2a-7c86-4c7c-a761-ed2100dff196">Class A Common Stock, par value $0.00001 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="C_4c81611c-51a9-4e18-94cc-43410fdf35c3"
      id="F_368be15e-776f-4c10-b5e2-d6d20e1d8ea3">SEER</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="C_4c81611c-51a9-4e18-94cc-43410fdf35c3"
      id="F_e589f265-993e-485e-b444-0b19b11fb324">NASDAQ</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="C_01d0f417-5669-45a0-91d0-784ee5c1a5a1"
      id="F_63d0a844-ec99-4a96-92fb-570714e7f68a">Preferred Stock Purchase Rights</dei:Security12bTitle>
    <dei:SecurityExchangeName
      contextRef="C_01d0f417-5669-45a0-91d0-784ee5c1a5a1"
      id="F_aa329f87-2f12-4ae6-baf4-027db3646152">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="C_20437e1c-630e-4bd9-89d8-17a795a95f8f"
      id="F_00922f5e-0b0f-4efc-a73f-d9055cca3db7">false</dei:EntityEmergingGrowthCompany>
</xbrl>
