<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>499</ContextCount>
  <ElementCount>724</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>140</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>8</UnitCount>
  <MyReports>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000010001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010002 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020003 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030004 - Statement - Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedStatementsofOperations</Role>
      <ShortName>Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040005 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedStatementsofComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050006 - Statement - Consolidated Statements of Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedStatementsofComprehensiveIncomeParenthetical</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060007 - Statement - Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedStatementsofStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070008 - Statement - Consolidated Statements of Stockholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedStatementsofStockholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080009 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ConsolidatedStatementsofCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>210011001 - Disclosure - Description of Business and Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPolicies</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>210161002 - Disclosure - Recent Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RecentAccountingPronouncements</Role>
      <ShortName>Recent Accounting Pronouncements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>210171003 - Disclosure - Revenue from Contracts with Customer</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RevenuefromContractswithCustomer</Role>
      <ShortName>Revenue from Contracts with Customer</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>210241004 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/Acquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>210301005 - Disclosure - Property and Equipment, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PropertyandEquipmentNet</Role>
      <ShortName>Property and Equipment, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>210341006 - Disclosure - Goodwill and Other Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GoodwillandOtherIntangibleAssets</Role>
      <ShortName>Goodwill and Other Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>210401007 - Disclosure - Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/Investments</Role>
      <ShortName>Investments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>210441008 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>210511009 - Disclosure - Accruals and Other Current Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AccrualsandOtherCurrentLiabilities</Role>
      <ShortName>Accruals and Other Current Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>210541010 - Disclosure - Long???Term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebt</Role>
      <ShortName>Long???Term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>210651011 - Disclosure - Executive Bonus Plan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ExecutiveBonusPlan</Role>
      <ShortName>Executive Bonus Plan</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>210671012 - Disclosure - Retirement Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RetirementPlans</Role>
      <ShortName>Retirement Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>210701013 - Disclosure - Preferred and Common Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PreferredandCommonStock</Role>
      <ShortName>Preferred and Common Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>210751014 - Disclosure - Accumulated Other Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AccumulatedOtherComprehensiveLoss</Role>
      <ShortName>Accumulated Other Comprehensive Loss</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>210781015 - Disclosure - Equity Awards and Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstruments</Role>
      <ShortName>Equity Awards and Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>210911016 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>210991017 - Disclosure - Fair Value of Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/FairValueofFinancialInstruments</Role>
      <ShortName>Fair Value of Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>211051018 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>211071019 - Disclosure - Geographic Data</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GeographicData</Role>
      <ShortName>Geographic Data</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>211101020 - Disclosure - Interest Expense, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/InterestExpenseNet</Role>
      <ShortName>Interest Expense, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>211131021 - Disclosure - Other Income (Expense), Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/OtherIncomeExpenseNet</Role>
      <ShortName>Other Income (Expense), Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>211161022 - Disclosure - Realignment Costs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RealignmentCosts</Role>
      <ShortName>Realignment Costs</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>211211023 - Disclosure - Net Income Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/NetIncomePerShare</Role>
      <ShortName>Net Income Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>220022001 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPolicies</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>230033001 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPolicies</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>230183002 - Disclosure - Revenue from Contracts with Customer (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RevenuefromContractswithCustomerTables</Role>
      <ShortName>Revenue from Contracts with Customer (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/RevenuefromContractswithCustomer</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>230253003 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/Acquisitions</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>230313004 - Disclosure - Property and Equipment, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PropertyandEquipmentNetTables</Role>
      <ShortName>Property and Equipment, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/PropertyandEquipmentNet</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>230353005 - Disclosure - Goodwill and Other Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GoodwillandOtherIntangibleAssetsTables</Role>
      <ShortName>Goodwill and Other Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/GoodwillandOtherIntangibleAssets</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>230413006 - Disclosure - Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/InvestmentsTables</Role>
      <ShortName>Investments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/Investments</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>230453007 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/Leases</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>230523008 - Disclosure - Accruals and Other Current Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AccrualsandOtherCurrentLiabilitiesTables</Role>
      <ShortName>Accruals and Other Current Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/AccrualsandOtherCurrentLiabilities</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>230553009 - Disclosure - Long???Term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebtTables</Role>
      <ShortName>Long???Term Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/LongTermDebt</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>230683010 - Disclosure - Retirement Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RetirementPlansTables</Role>
      <ShortName>Retirement Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/RetirementPlans</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>230713011 - Disclosure - Preferred and Common Stock (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PreferredandCommonStockTables</Role>
      <ShortName>Preferred and Common Stock (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/PreferredandCommonStock</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>230763012 - Disclosure - Accumulated Other Comprehensive Loss (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AccumulatedOtherComprehensiveLossTables</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/AccumulatedOtherComprehensiveLoss</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>230793013 - Disclosure - Equity Awards and Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsTables</Role>
      <ShortName>Equity Awards and Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/EquityAwardsandInstruments</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>230923014 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/IncomeTaxes</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>231003015 - Disclosure - Fair Value of Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/FairValueofFinancialInstrumentsTables</Role>
      <ShortName>Fair Value of Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/FairValueofFinancialInstruments</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>231083016 - Disclosure - Geographic Data (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GeographicDataTables</Role>
      <ShortName>Geographic Data (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/GeographicData</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>231113017 - Disclosure - Interest Expense, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/InterestExpenseNetTables</Role>
      <ShortName>Interest Expense, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/InterestExpenseNet</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>231143018 - Disclosure - Other Income (Expense), Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/OtherIncomeExpenseNetTables</Role>
      <ShortName>Other Income (Expense), Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/OtherIncomeExpenseNet</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>231173019 - Disclosure - Realignment Costs (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RealignmentCostsTables</Role>
      <ShortName>Realignment Costs (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/RealignmentCosts</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>231223020 - Disclosure - Net Income Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/NetIncomePerShareTables</Role>
      <ShortName>Net Income Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bentley.com/role/NetIncomePerShare</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>240044001 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Initial and Follow-On Public Offering (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesInitialandFollowOnPublicOfferingDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Initial and Follow-On Public Offering (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>240054002 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Convertible Senior Notes (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesConvertibleSeniorNotesDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Convertible Senior Notes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>240064003 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Special Dividend (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesSpecialDividendDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Special Dividend (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>240074004 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Business Combinations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesBusinessCombinationsDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Business Combinations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>240084005 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Software Development Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesSoftwareDevelopmentCostsDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Software Development Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>240094006 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Deferred Compensation &amp; Advertising Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesDeferredCompensationAdvertisingExpenseDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Deferred Compensation &amp; Advertising Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>240104007 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Derivative Arrangements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesDerivativeArrangementsDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Derivative Arrangements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>240114008 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Rollforward of Accounts Receivable Allowance for Doubtful Accounts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesRollforwardofAccountsReceivableAllowanceforDoubtfulAccountsDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Rollforward of Accounts Receivable Allowance for Doubtful Accounts (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>240124009 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Schedule of Property and Equipment Useful Lives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesScheduleofPropertyandEquipmentUsefulLivesDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Schedule of Property and Equipment Useful Lives (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>240134010 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesLeasesDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>240144011 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesGoodwillandOtherIntangibleAssetsDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>240154012 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesInvestmentsDetails</Role>
      <ShortName>Description of Business and Summary of Significant Accounting Policies - Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>240194013 - Disclosure - Revenue from Contracts with Customer - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RevenuefromContractswithCustomerNarrativeDetails</Role>
      <ShortName>Revenue from Contracts with Customer - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>240204014 - Disclosure - Revenue from Contracts with Customer - Schedule of Contract Assets and Deferred Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RevenuefromContractswithCustomerScheduleofContractAssetsandDeferredRevenueDetails</Role>
      <ShortName>Revenue from Contracts with Customer - Schedule of Contract Assets and Deferred Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>240214015 - Disclosure - Revenue from Contracts with Customer - Performance Obligation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RevenuefromContractswithCustomerPerformanceObligationDetails</Role>
      <ShortName>Revenue from Contracts with Customer - Performance Obligation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>240224016 - Disclosure - Revenue from Contracts with Customer - Schedule of Revenue Disaggregation by Type (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RevenuefromContractswithCustomerScheduleofRevenueDisaggregationbyTypeDetails</Role>
      <ShortName>Revenue from Contracts with Customer - Schedule of Revenue Disaggregation by Type (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>240234017 - Disclosure - Revenue from Contracts with Customer - Schedule of Revenue Disaggregation by Location (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RevenuefromContractswithCustomerScheduleofRevenueDisaggregationbyLocationDetails</Role>
      <ShortName>Revenue from Contracts with Customer - Schedule of Revenue Disaggregation by Location (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>240264018 - Disclosure - Acquisitions - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AcquisitionsNarrativeDetails</Role>
      <ShortName>Acquisitions - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>240274019 - Disclosure - Acquisitions - Schedule of Cash Paid and Acquired for Acquisitions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AcquisitionsScheduleofCashPaidandAcquiredforAcquisitionsDetails</Role>
      <ShortName>Acquisitions - Schedule of Cash Paid and Acquired for Acquisitions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>240284020 - Disclosure - Acquisitions - Schedule of Contingent and Non-Contingent Consideration Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AcquisitionsScheduleofContingentandNonContingentConsiderationFairValueDetails</Role>
      <ShortName>Acquisitions - Schedule of Contingent and Non-Contingent Consideration Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>240294021 - Disclosure - Acquisitions - Schedule of Consideration and Net Assets Acquired (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AcquisitionsScheduleofConsiderationandNetAssetsAcquiredDetails</Role>
      <ShortName>Acquisitions - Schedule of Consideration and Net Assets Acquired (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>240324022 - Disclosure - Property and Equipment, Net - Schedule of Property and Equipment, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PropertyandEquipmentNetScheduleofPropertyandEquipmentNetDetails</Role>
      <ShortName>Property and Equipment, Net - Schedule of Property and Equipment, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>240334023 - Disclosure - Property and Equipment, Net - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PropertyandEquipmentNetNarrativeDetails</Role>
      <ShortName>Property and Equipment, Net - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>240364024 - Disclosure - Goodwill and Other Intangible Assets - Carrying Amount of Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GoodwillandOtherIntangibleAssetsCarryingAmountofGoodwillDetails</Role>
      <ShortName>Goodwill and Other Intangible Assets - Carrying Amount of Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>240374025 - Disclosure - Goodwill and Other Intangible Assets - Intangible Assets Other than Goodwill (Details )</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GoodwillandOtherIntangibleAssetsIntangibleAssetsOtherthanGoodwillDetails</Role>
      <ShortName>Goodwill and Other Intangible Assets - Intangible Assets Other than Goodwill (Details )</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>240384026 - Disclosure - Goodwill and Other Intangible Assets - Aggregate Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GoodwillandOtherIntangibleAssetsAggregateAmortizationExpenseDetails</Role>
      <ShortName>Goodwill and Other Intangible Assets - Aggregate Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>240394027 - Disclosure - Goodwill and Other Intangible Assets - Future Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GoodwillandOtherIntangibleAssetsFutureAmortizationExpenseDetails</Role>
      <ShortName>Goodwill and Other Intangible Assets - Future Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>240424028 - Disclosure - Investments - Schedule of Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/InvestmentsScheduleofInvestmentsDetails</Role>
      <ShortName>Investments - Schedule of Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>240434029 - Disclosure - Investments - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/InvestmentsNarrativeDetails</Role>
      <ShortName>Investments - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>240464030 - Disclosure - Leases - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LeasesNarrativeDetails</Role>
      <ShortName>Leases - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>240474031 - Disclosure - Leases - Lease Cost (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LeasesLeaseCostDetails</Role>
      <ShortName>Leases - Lease Cost (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>240484032 - Disclosure - Leases - Other Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LeasesOtherInformationDetails</Role>
      <ShortName>Leases - Other Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>240494033 - Disclosure - Leases - Maturities of Operating Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LeasesMaturitiesofOperatingLeaseLiabilitiesDetails</Role>
      <ShortName>Leases - Maturities of Operating Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>240504034 - Disclosure - Leases - Supplemental Balance Sheet (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LeasesSupplementalBalanceSheetDetails</Role>
      <ShortName>Leases - Supplemental Balance Sheet (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>240534035 - Disclosure - Accruals and Other Current Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AccrualsandOtherCurrentLiabilitiesDetails</Role>
      <ShortName>Accruals and Other Current Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/AccrualsandOtherCurrentLiabilitiesTables</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>240564036 - Disclosure - Long???Term Debt - Schedule of Long-Term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebtScheduleofLongTermDebtDetails</Role>
      <ShortName>Long???Term Debt - Schedule of Long-Term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>240574037 - Disclosure - Long???Term Debt - Bank Credit Facility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebtBankCreditFacilityDetails</Role>
      <ShortName>Long???Term Debt - Bank Credit Facility (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>240584038 - Disclosure - Long???Term Debt - 2026 Convertible Senior Notes (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebt2026ConvertibleSeniorNotesDetails</Role>
      <ShortName>Long???Term Debt - 2026 Convertible Senior Notes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>240594039 - Disclosure - Long???Term Debt - 2026 Notes Capped Call Options (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebt2026NotesCappedCallOptionsDetails</Role>
      <ShortName>Long???Term Debt - 2026 Notes Capped Call Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>240604040 - Disclosure - Long???Term Debt - 2027 Convertible Senior Notes (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebt2027ConvertibleSeniorNotesDetails</Role>
      <ShortName>Long???Term Debt - 2027 Convertible Senior Notes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>240614041 - Disclosure - Long???Term Debt - 2027 Notes Capped Call Options (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebt2027NotesCappedCallOptionsDetails</Role>
      <ShortName>Long???Term Debt - 2027 Notes Capped Call Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>240624042 - Disclosure - Long???Term Debt - Schedule of Interest Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebtScheduleofInterestExpenseDetails</Role>
      <ShortName>Long???Term Debt - Schedule of Interest Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>240634043 - Disclosure - Long???Term Debt - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebtNarrativeDetails</Role>
      <ShortName>Long???Term Debt - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>240644044 - Disclosure - Long???Term Debt - Long-Term Debt, Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/LongTermDebtLongTermDebtMaturityDetails</Role>
      <ShortName>Long???Term Debt - Long-Term Debt, Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>240664045 - Disclosure - Executive Bonus Plan - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/ExecutiveBonusPlanNarrativeDetails</Role>
      <ShortName>Executive Bonus Plan - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>240694046 - Disclosure - Retirement Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RetirementPlansDetails</Role>
      <ShortName>Retirement Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/RetirementPlansTables</ParentRole>
      <Position>99</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>240724047 - Disclosure - Preferred and Common Stock - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PreferredandCommonStockNarrativeDetails</Role>
      <ShortName>Preferred and Common Stock - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>240734048 - Disclosure - Preferred and Common Stock - Schedule of Dividends (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PreferredandCommonStockScheduleofDividendsDetails</Role>
      <ShortName>Preferred and Common Stock - Schedule of Dividends (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>240744049 - Disclosure - Preferred and Common Stock- Global Employee Stock Purchase Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/PreferredandCommonStockGlobalEmployeeStockPurchasePlanDetails</Role>
      <ShortName>Preferred and Common Stock- Global Employee Stock Purchase Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>240774050 - Disclosure - Accumulated Other Comprehensive Loss - Rollforward of AOCI (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/AccumulatedOtherComprehensiveLossRollforwardofAOCIDetails</Role>
      <ShortName>Accumulated Other Comprehensive Loss - Rollforward of AOCI (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>240804051 - Disclosure - Equity Awards and Instruments - Incentive Plan Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsIncentivePlanNarrativeDetails</Role>
      <ShortName>Equity Awards and Instruments - Incentive Plan Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>240814052 - Disclosure - Equity Awards and Instruments - Equity Awards Stock Options Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsEquityAwardsStockOptionsNarrativeDetails</Role>
      <ShortName>Equity Awards and Instruments - Equity Awards Stock Options Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>240824053 - Disclosure - Equity Awards and Instruments - Summary of Stock-Based Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsSummaryofStockBasedCompensationExpenseDetails</Role>
      <ShortName>Equity Awards and Instruments - Summary of Stock-Based Compensation Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>240834054 - Disclosure - Equity Awards and Instruments - Schedule of Fair Value Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsScheduleofFairValueAssumptionsDetails</Role>
      <ShortName>Equity Awards and Instruments - Schedule of Fair Value Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>240844055 - Disclosure - Equity Awards and Instruments - Options Outstanding Rollforward (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsOptionsOutstandingRollforwardDetails</Role>
      <ShortName>Equity Awards and Instruments - Options Outstanding Rollforward (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>240854056 - Disclosure - Equity Awards and Instruments - Stock Options Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsStockOptionsNarrativeDetails</Role>
      <ShortName>Equity Awards and Instruments - Stock Options Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>240864057 - Disclosure - Equity Awards and Instruments - Acquisition Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsAcquisitionOptionsDetails</Role>
      <ShortName>Equity Awards and Instruments - Acquisition Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>240874058 - Disclosure - Equity Awards and Instruments - Restricted Stock and RSUs Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsRestrictedStockandRSUsActivityDetails</Role>
      <ShortName>Equity Awards and Instruments - Restricted Stock and RSUs Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>240884059 - Disclosure - Equity Awards and Instruments - Restricted Stock and Restricted Stock Units Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsRestrictedStockandRestrictedStockUnitsNarrativeDetails</Role>
      <ShortName>Equity Awards and Instruments - Restricted Stock and Restricted Stock Units Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>240894060 - Disclosure - Equity Awards and Instruments - Stock Grants (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsStockGrantsDetails</Role>
      <ShortName>Equity Awards and Instruments - Stock Grants (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>240904061 - Disclosure - Equity Awards and Instruments - ESPP (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/EquityAwardsandInstrumentsESPPDetails</Role>
      <ShortName>Equity Awards and Instruments - ESPP (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/EquityAwardsandInstrumentsTables</ParentRole>
      <Position>114</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>240934062 - Disclosure - Income Taxes - Schedule of Income before Income Tax, Domestic and International (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxesScheduleofIncomebeforeIncomeTaxDomesticandInternationalDetails</Role>
      <ShortName>Income Taxes - Schedule of Income before Income Tax, Domestic and International (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>240944063 - Disclosure - Income Taxes - Schedule of Components of Income Tax (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxesScheduleofComponentsofIncomeTaxDetails</Role>
      <ShortName>Income Taxes - Schedule of Components of Income Tax (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>116</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>240954064 - Disclosure - Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxesScheduleofEffectiveIncomeTaxRateReconciliationDetails</Role>
      <ShortName>Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>117</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>240964065 - Disclosure - Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxesScheduleofDeferredTaxAssetsandLiabilitiesDetails</Role>
      <ShortName>Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>240974066 - Disclosure - Income Taxes - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>240984067 - Disclosure - Income Taxes - Unrecognized Tax Benefits Rollfoward (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/IncomeTaxesUnrecognizedTaxBenefitsRollfowardDetails</Role>
      <ShortName>Income Taxes - Unrecognized Tax Benefits Rollfoward (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>241014068 - Disclosure - Fair Value of Financial Instruments - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/FairValueofFinancialInstrumentsNarrativeDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>241024069 - Disclosure - Fair Value of Financial Instruments - Interest Rate Swap Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/FairValueofFinancialInstrumentsInterestRateSwapActivityDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Interest Rate Swap Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>241034070 - Disclosure - Fair Value of Financial Instruments - Fair Value of Financial Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/FairValueofFinancialInstrumentsFairValueofFinancialAssetsandLiabilitiesDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Fair Value of Financial Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>241044071 - Disclosure - Fair Value of Financial Instruments - Reconciliation of the Changes in Fair Value of Financial Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/FairValueofFinancialInstrumentsReconciliationoftheChangesinFairValueofFinancialLiabilitiesDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Reconciliation of the Changes in Fair Value of Financial Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>124</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>241064072 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/CommitmentsandContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/CommitmentsandContingencies</ParentRole>
      <Position>125</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>241094073 - Disclosure - Geographic Data (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/GeographicDataDetails</Role>
      <ShortName>Geographic Data (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/GeographicDataTables</ParentRole>
      <Position>126</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>241124074 - Disclosure - Interest Expense, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/InterestExpenseNetDetails</Role>
      <ShortName>Interest Expense, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/InterestExpenseNetTables</ParentRole>
      <Position>127</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>241154075 - Disclosure - Other Income (Expense), Net - Schedule of Other Income (Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/OtherIncomeExpenseNetScheduleofOtherIncomeExpenseDetails</Role>
      <ShortName>Other Income (Expense), Net - Schedule of Other Income (Expense) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bentley.com/role/OtherIncomeExpenseNetTables</ParentRole>
      <Position>128</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R129.htm</HtmlFileName>
      <LongName>241184076 - Disclosure - Realignment Costs - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RealignmentCostsNarrativeDetails</Role>
      <ShortName>Realignment Costs - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>129</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R130.htm</HtmlFileName>
      <LongName>241194077 - Disclosure - Realignment Costs - Realignment Activities Rollforward (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RealignmentCostsRealignmentActivitiesRollforwardDetails</Role>
      <ShortName>Realignment Costs - Realignment Activities Rollforward (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>130</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>241204078 - Disclosure - Realignment Costs - Schedule of Realignment Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/RealignmentCostsScheduleofRealignmentCostsDetails</Role>
      <ShortName>Realignment Costs - Schedule of Realignment Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>131</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>241234079 - Disclosure - Net Income Per Share - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/NetIncomePerShareNarrativeDetails</Role>
      <ShortName>Net Income Per Share - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>132</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R133.htm</HtmlFileName>
      <LongName>241244080 - Disclosure - Net Income Per Share - Schedule of Basic and Diluted Net (Loss) Income Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/NetIncomePerShareScheduleofBasicandDilutedNetLossIncomePerShareDetails</Role>
      <ShortName>Net Income Per Share - Schedule of Basic and Diluted Net (Loss) Income Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>133</Position>
    </Report>
    <Report instance="bsy-20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R134.htm</HtmlFileName>
      <LongName>241254081 - Disclosure - Net Income Per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bentley.com/role/NetIncomePerShareScheduleofAntidilutiveSecuritiesExcludedfromComputationofEarningsPerShareDetails</Role>
      <ShortName>Net Income Per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>134</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-K" original="bsy-20211231.htm">bsy-20211231.htm</File>
    <File>bsy-20211231.xsd</File>
    <File>bsy-20211231_cal.xml</File>
    <File>bsy-20211231_def.xml</File>
    <File>bsy-20211231_lab.xml</File>
    <File>bsy-20211231_pre.xml</File>
    <File>exhibit1010-amendmentno120.htm</File>
    <File>exhibit211-2021q4.htm</File>
    <File>exhibit231-2021q4.htm</File>
    <File>exhibit311-2021q4.htm</File>
    <File>exhibit312-2021q4.htm</File>
    <File>exhibit321-2021q4.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>bsy-20211231_g1.jpg</File>
    <File>bsy-20211231_g2.jpg</File>
    <File>bsy-20211231_g3.jpg</File>
    <File>bsy-20211231_g4.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="1771">http://fasb.org/us-gaap/2021-01-31</BaseTaxonomy>
    <BaseTaxonomy items="38">http://xbrl.sec.gov/dei/2021q4</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
