<?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="ck0001726445-20260701.xsd" xlink:type="simple"/>
    <context id="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001726445</identifier>
        </entity>
        <period>
            <startDate>2026-07-01</startDate>
            <endDate>2026-07-01</endDate>
        </period>
    </context>
    <context id="C_3d0cfea1-41d6-4eed-8a6d-18338b17c747">
        <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>2026-07-01</startDate>
            <endDate>2026-07-01</endDate>
        </period>
    </context>
    <context id="C_77013c24-0922-435f-8f1d-27f4ccf31d34">
        <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>2026-07-01</startDate>
            <endDate>2026-07-01</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_3251831a-b5aa-443a-abec-bd0ef0593080">0001726445</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_07b13765-b96b-4cc3-9f02-20c0a08f2b66">false</dei:AmendmentFlag>
    <dei:NoTradingSymbolFlag
      contextRef="C_3d0cfea1-41d6-4eed-8a6d-18338b17c747"
      id="F_4b9625a4-b8be-493d-8924-6783bede8334">true</dei:NoTradingSymbolFlag>
    <dei:DocumentType
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_4034e61c-d8d3-43c8-a902-47c54606debd">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_b0a60856-1993-40b6-ae04-96be6ff085a4">2026-07-01</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_ed6ba94d-efcc-46b3-8c88-7ebbf3940897">Seer, Inc.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_2cd956c6-47f7-4488-94c7-e1a098b77627">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_e8ce34ef-8088-49c2-83d7-5e9ebfc29500">001-39747</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_5b80efd0-841d-43cc-ab01-69815faf0926">82-1153150</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_80b4d21f-30fb-4805-aa7b-48caabc842e8">3800 Bridge Parkway</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_41474a74-1a85-4dad-8bc2-dfe63b86ff3a">Suite 102</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_9f3059ca-bc2c-4547-99f2-2e6f7f1a336d">Redwood City</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_5101a239-7eef-4329-b00e-4108db908f6b">CA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_655a2b24-93dc-4c38-b012-9c2788806397">94065</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_13d73202-6cfc-4b6c-abf4-589c672d211f">650</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_f1710566-cfac-4bdb-b780-50e27f04d2d1">453-0000 </dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_d153ca07-5523-4b7e-9680-286c60554861">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_c1c4957c-9ab7-4f93-8a87-2a7d7ef36845">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_53c6d7e2-8148-4e42-966a-7c3c15b80c46">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_6eef2cbf-17fb-4f41-b9a7-36d878789b83">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="C_77013c24-0922-435f-8f1d-27f4ccf31d34"
      id="F_1622d33d-dae9-4605-9286-3365ba9b7506">Class A Common Stock, par value $0.00001 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="C_77013c24-0922-435f-8f1d-27f4ccf31d34"
      id="F_6d142a02-6048-44b2-83e3-58db7cf10861">SEER</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="C_77013c24-0922-435f-8f1d-27f4ccf31d34"
      id="F_605f7908-4470-4d28-b6c0-221424ab30d7">NASDAQ</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="C_3d0cfea1-41d6-4eed-8a6d-18338b17c747"
      id="F_d1e00942-5961-419c-94e6-a997953e6b6a">Preferred Stock Purchase Rights</dei:Security12bTitle>
    <dei:SecurityExchangeName
      contextRef="C_3d0cfea1-41d6-4eed-8a6d-18338b17c747"
      id="F_4c8f39b3-33f1-47aa-95b3-2e8bdd5b06b3">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="C_39397cf9-4eda-491f-8f9f-7fdbf6a82534"
      id="F_745522bf-b4e7-493a-8f99-ea49b6380b42">false</dei:EntityEmergingGrowthCompany>
</xbrl>
