<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xml:lang="en-US"
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2020-01-31"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="ssd-20210323.xsd" xlink:type="simple"/>
    <context id="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000920371</identifier>
        </entity>
        <period>
            <startDate>2021-03-23</startDate>
            <endDate>2021-03-23</endDate>
        </period>
    </context>
    <dei:EntityRegistrantName
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl80L2ZyYWc6ZTc2YjM0YjNiMGJhNGNjOGE2OTEzNzEwYmExOWMwM2EvdGFibGU6YmFlYzI1ZmI0MzJjNGUzZGI0OWJjYjkzNmNlMWQ1ZjcvdGFibGVyYW5nZTpiYWVjMjVmYjQzMmM0ZTNkYjQ5YmNiOTM2Y2UxZDVmN18wLTEtMS0xLTA_3b565e99-88d4-482f-a436-55714e33a7ff">SIMPSON MANUFACTURING CO INC /CA/</dei:EntityRegistrantName>
    <dei:EntityCentralIndexKey
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl80L2ZyYWc6ZTc2YjM0YjNiMGJhNGNjOGE2OTEzNzEwYmExOWMwM2EvdGFibGU6YmFlYzI1ZmI0MzJjNGUzZGI0OWJjYjkzNmNlMWQ1ZjcvdGFibGVyYW5nZTpiYWVjMjVmYjQzMmM0ZTNkYjQ5YmNiOTM2Y2UxZDVmN18xLTEtMS0xLTA_91412bdf-9250-480b-b6de-6814e75b97fd">0000920371</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl80L2ZyYWc6ZTc2YjM0YjNiMGJhNGNjOGE2OTEzNzEwYmExOWMwM2EvdGFibGU6YmFlYzI1ZmI0MzJjNGUzZGI0OWJjYjkzNmNlMWQ1ZjcvdGFibGVyYW5nZTpiYWVjMjVmYjQzMmM0ZTNkYjQ5YmNiOTM2Y2UxZDVmN18yLTEtMS0xLTA_4209bfbd-be93-42d1-82a3-b8493b23549e">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjEy_3507ff20-72f0-425f-a99b-c9e1e3177013">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8yMzQ_ea7a8359-707b-482f-949a-0468a445dc83">2021-03-23</dei:DocumentPeriodEndDate>
    <dei:EntityIncorporationStateCountryCode
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6OTcyMjg4NWVmNGUwNDUzYmI0MWY1YmZjM2JhNDUxYmIvdGFibGVyYW5nZTo5NzIyODg1ZWY0ZTA0NTNiYjQxZjViZmMzYmE0NTFiYl8wLTAtMS0xLTA_61562d52-9a8c-4fca-8816-19a092a0cced">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6OTcyMjg4NWVmNGUwNDUzYmI0MWY1YmZjM2JhNDUxYmIvdGFibGVyYW5nZTo5NzIyODg1ZWY0ZTA0NTNiYjQxZjViZmMzYmE0NTFiYl8wLTItMS0xLTA_b46ca66a-26fe-420c-9de8-e399da4517c4">1-13429</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6OTcyMjg4NWVmNGUwNDUzYmI0MWY1YmZjM2JhNDUxYmIvdGFibGVyYW5nZTo5NzIyODg1ZWY0ZTA0NTNiYjQxZjViZmMzYmE0NTFiYl8wLTQtMS0xLTA_62f20704-56a3-4791-b909-fc8d72f64cb4">94-3196943</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjEz_9fc491fb-c580-458a-abd6-afaa3cc1fa54">5956 W. Las Positas Boulevard</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjE0_c38efd8e-36f6-46e5-9f0e-c97d0f63ce0e">Pleasanton</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjA3_bd80efb8-cf5a-4aa9-a480-ce1e05dc8bff">CA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjA4_a0641f94-3f94-4e39-a720-24838e2fe67c">94588</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjA5_cfcdda28-0920-4d18-b760-18eb8240cddb">925</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjEw_aefba18c-61a2-4f6d-ac02-ea2107ca689e">560-9000</dei:LocalPhoneNumber>
    <dei:Security12bTitle
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6ZmUwZTZmZjYwNDdlNDRhZTk2MWM0ZTZiYjQ1M2EwNzMvdGFibGVyYW5nZTpmZTBlNmZmNjA0N2U0NGFlOTYxYzRlNmJiNDUzYTA3M18yLTAtMS0xLTA_cdd0d208-5283-4882-9173-72147e58acd6">Common Stock, par value $0.01 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6ZmUwZTZmZjYwNDdlNDRhZTk2MWM0ZTZiYjQ1M2EwNzMvdGFibGVyYW5nZTpmZTBlNmZmNjA0N2U0NGFlOTYxYzRlNmJiNDUzYTA3M18yLTEtMS0xLTA_51c0c8ff-64e8-43e5-b873-1f037d7cec84">SSD</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6ZmUwZTZmZjYwNDdlNDRhZTk2MWM0ZTZiYjQ1M2EwNzMvdGFibGVyYW5nZTpmZTBlNmZmNjA0N2U0NGFlOTYxYzRlNmJiNDUzYTA3M18yLTItMS0xLTA_aa0d5636-ff04-4b63-8468-f15b9fa505f9">NYSE</dei:SecurityExchangeName>
    <dei:WrittenCommunications
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6ZjE3NGMwMmIyNzY1NDBjYjkzMGYwYzUxYzFlZGIxNTAvdGFibGVyYW5nZTpmMTc0YzAyYjI3NjU0MGNiOTMwZjBjNTFjMWVkYjE1MF8wLTAtMS0xLTA_06efa22f-f768-4d54-8e6a-e4b65e6d423b">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6ZjE3NGMwMmIyNzY1NDBjYjkzMGYwYzUxYzFlZGIxNTAvdGFibGVyYW5nZTpmMTc0YzAyYjI3NjU0MGNiOTMwZjBjNTFjMWVkYjE1MF8xLTAtMS0xLTA_a3eb0d78-cb15-4d82-ad91-b96d9e6feb09">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6ZjE3NGMwMmIyNzY1NDBjYjkzMGYwYzUxYzFlZGIxNTAvdGFibGVyYW5nZTpmMTc0YzAyYjI3NjU0MGNiOTMwZjBjNTFjMWVkYjE1MF8yLTAtMS0xLTA_07f046e4-186e-49d5-a391-7e7ef8eff42a">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGFibGU6ZjE3NGMwMmIyNzY1NDBjYjkzMGYwYzUxYzFlZGIxNTAvdGFibGVyYW5nZTpmMTc0YzAyYjI3NjU0MGNiOTMwZjBjNTFjMWVkYjE1MF8zLTAtMS0xLTA_50d2cd09-0df4-4c60-b771-66da5d681d2e">false</dei:PreCommencementIssuerTenderOffer>
    <dei:EntityEmergingGrowthCompany
      contextRef="i427bd68f0e894e659b32f2ebbbc60fb9_D20210323-20210323"
      id="id3VybDovL2RvY3MudjEvZG9jOmJiMmFmNTcyMjhmZTQ1MDdhM2ZhMjBkMzcyNmQ5MTAyL3NlYzpiYjJhZjU3MjI4ZmU0NTA3YTNmYTIwZDM3MjZkOTEwMl8xL2ZyYWc6YTkyYjJlY2ZlNWNiNDRhNGJkODE2ZDAzYzliYTcxYWUvdGV4dHJlZ2lvbjphOTJiMmVjZmU1Y2I0NGE0YmQ4MTZkMDNjOWJhNzFhZV8xMjEx_7681e126-2881-46f6-abd2-f58fca949673">false</dei:EntityEmergingGrowthCompany>
</xbrl>
