<?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="wso-20261021.xsd" xlink:type="simple"/>
    <context id="C_c53848bb-7966-42f8-9cbe-337c341483ca">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000105016</identifier>
        </entity>
        <period>
            <startDate>2026-10-21</startDate>
            <endDate>2026-10-21</endDate>
        </period>
    </context>
    <context id="C_ca892929-5aec-4319-9dc0-93fd317fbd58">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000105016</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">us-gaap:CommonClassBMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-10-21</startDate>
            <endDate>2026-10-21</endDate>
        </period>
    </context>
    <context id="C_f3670286-28f3-4571-82ce-223ba718f596">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000105016</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">us-gaap:CommonStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-10-21</startDate>
            <endDate>2026-10-21</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_c0b2140a-63b8-4c64-bee2-61815d1f67dc">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_460589ee-8df8-4943-a0cc-d4450f1027cf">0000105016</dei:EntityCentralIndexKey>
    <dei:DocumentType
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_e07b328d-6fe9-427c-8348-7230a6e4e683">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_0d1e0745-6da7-40d3-b7dd-913c2b384637">2026-10-21</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_6fe767c3-71a3-4617-b9c1-4476ff9f9cb0">WATSCO, INC.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_52c94c99-0845-4068-9fb3-f36357db2345">FL</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_47a6ae7c-a6c2-4771-a431-22f48ba93fb4">1-5581</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_eaaae7bb-e11f-4dfe-bac6-e312938ed04a">59-0778222</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_808f1a5d-7afb-4d70-be83-a00c7caaa112">2665 South Bayshore Drive</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_a9eef148-0d46-4fda-be9e-e49e53c2d5d1">Suite 901</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_0d79b315-9039-4bf8-aa7e-9808e9c63286">Miami</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_04ef953c-3026-4e43-9fef-c6fb12891de3">FL</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_e8c83b96-fe89-4639-a82e-3323715f54ca">33133</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_f4f5218f-4f25-45d1-b91c-4848c6a2e449">(305)</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_0bd73906-64b8-46f2-a0b5-483113d63e2e">714-4100</dei:LocalPhoneNumber>
    <dei:EntityInformationFormerLegalOrRegisteredName
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_f3d54e20-f6f4-43ac-8c12-108595db448d">N/A</dei:EntityInformationFormerLegalOrRegisteredName>
    <dei:WrittenCommunications
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_4a2f40b4-cf37-4f22-bff5-e15c8132e406">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_c618d3cb-b255-4615-9446-2e99f186d50a">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_01e9a69b-fa5c-423e-a253-9fccac6ff810">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_3b28dbbb-763b-4dd0-a028-e0c22eb7036d">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="C_f3670286-28f3-4571-82ce-223ba718f596"
      id="F_a8998912-468c-4ae6-a2d3-0ae78be327c5">Common stock, $0.50 par value</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="C_f3670286-28f3-4571-82ce-223ba718f596"
      id="F_70456092-32c3-418a-a90c-be35efa57860">WSO</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="C_f3670286-28f3-4571-82ce-223ba718f596"
      id="F_32ddb441-976c-4f47-a68e-05744ae7223c">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="C_ca892929-5aec-4319-9dc0-93fd317fbd58"
      id="F_59ab0d80-2e05-43b8-aa66-f7f5875103fc">Class B common stock, $0.50 par value</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="C_ca892929-5aec-4319-9dc0-93fd317fbd58"
      id="F_a05e4094-3195-4499-aa80-532d65ae7587">WSOB</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="C_ca892929-5aec-4319-9dc0-93fd317fbd58"
      id="F_a2cfadb7-108a-43e5-bcc6-a2a255c0d0f5">NYSE</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="C_c53848bb-7966-42f8-9cbe-337c341483ca"
      id="F_abb44449-bbf0-481b-ac73-798c994ce548">false</dei:EntityEmergingGrowthCompany>
</xbrl>
