<?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/2025"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="cswi-20260526.xsd" xlink:type="simple"/>
    <context id="c-1">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001624794</identifier>
        </entity>
        <period>
            <startDate>2026-05-26</startDate>
            <endDate>2026-05-26</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey contextRef="c-1" id="f-21">0001624794</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag contextRef="c-1" id="f-22">true</dei:AmendmentFlag>
    <dei:AmendmentDescription contextRef="c-1" id="f-23">On May 26, 2026, CSW Industrials, Inc. (the &#x201c;Company&#x201d;) filed a Current Report on Form 8-K (the &#x201c;Original Report&#x201d;) that furnished as Exhibit 99.1 the Company&#x2019;s press release relating to financial results for the fiscal fourth quarter and full year ended March 31, 2026 (the &#x201c;Press Release&#x201d;).  After the issuance of the Press Release and the filing of the Original Report, the Company identified in the Press Release an inadvertent error in the year over year Non-GAAP revenue growth percentage calculation for the Contractor Solutions segment including the pre-acquisition revenue effect from the Aspen Manufacturing and MARS Parts acquisitions. As previously furnished, pages 4 and 15 of Exhibit 99.1 reflected an incorrect Non-GAAP revenue growth percentage for the Contractor Solutions segment including pre-acquisition revenue effect from recent acquisitions and an incorrect pre-acquisition revenue effect for recent acquisitions figure in the Non-GAAP reconciliation table captioned &#x201c;Reconciliation of Contractor Solutions Segment Reported Revenue to Revenue Calculated to Include Pre-Acquisition Revenue Effect&#x201d;, respectively.  This Form 8-K/A is being filed solely to furnish the Press Release as corrected.</dei:AmendmentDescription>
    <dei:DocumentType contextRef="c-1" id="f-1">8-K/A</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="c-1" id="f-2">2026-05-26</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName contextRef="c-1" id="f-3">CSW INDUSTRIALS, INC.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode contextRef="c-1" id="f-4">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber contextRef="c-1" id="f-5">001-37454</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber contextRef="c-1" id="f-6">47-2266942</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1 contextRef="c-1" id="f-7">5420 Lyndon B. Johnson Freeway, Suite 500</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown contextRef="c-1" id="f-8">Dallas</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince contextRef="c-1" id="f-9">TX</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode contextRef="c-1" id="f-10">75240</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode contextRef="c-1" id="f-11">214</dei:CityAreaCode>
    <dei:LocalPhoneNumber contextRef="c-1" id="f-12">884-3777</dei:LocalPhoneNumber>
    <dei:WrittenCommunications contextRef="c-1" id="f-13">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial contextRef="c-1" id="f-14">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer contextRef="c-1" id="f-15">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer contextRef="c-1" id="f-16">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle contextRef="c-1" id="f-17">Common Stock, par value $0.01 per share</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="c-1" id="f-18">CSW</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="c-1" id="f-19">NYSE</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany contextRef="c-1" id="f-20">false</dei:EntityEmergingGrowthCompany>
</xbrl>
