<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>276</ContextCount>
  <ElementCount>386</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>112</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>8</UnitCount>
  <MyReports>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover Page</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/CoverPage</Role>
      <ShortName>Cover Page</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>9952151 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>9952152 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952153 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952154 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>9952155 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE NON-CONTROLLING INTERESTS AND STOCKHOLDERS??? EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINREDEEMABLENONCONTROLLINGINTERESTSANDSTOCKHOLDERSEQUITY</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE NON-CONTROLLING INTERESTS AND STOCKHOLDERS??? EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952156 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952157 - Disclosure - BASIS OF PRESENTATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/BASISOFPRESENTATION</Role>
      <ShortName>BASIS OF PRESENTATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952158 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952159 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERS</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - BUSINESS ACQUISITIONS AND RELATED TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/BUSINESSACQUISITIONSANDRELATEDTRANSACTIONS</Role>
      <ShortName>BUSINESS ACQUISITIONS AND RELATED TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - GOODWILL AND INTANGIBLE ASSETS, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/GOODWILLANDINTANGIBLEASSETSNET</Role>
      <ShortName>GOODWILL AND INTANGIBLE ASSETS, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - ENERGY ASSETS, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/ENERGYASSETSNET</Role>
      <ShortName>ENERGY ASSETS, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - LEASES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/LEASES</Role>
      <ShortName>LEASES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - DEBT AND FINANCING LEASE LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DEBTANDFINANCINGLEASELIABILITIES</Role>
      <ShortName>DEBT AND FINANCING LEASE LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/COMMITMENTSANDCONTINGENCIES</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - FAIR VALUE MEASUREMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/FAIRVALUEMEASUREMENT</Role>
      <ShortName>FAIR VALUE MEASUREMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIES</Role>
      <ShortName>DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9952169 - Disclosure - VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/VARIABLEINTERESTENTITIESANDEQUITYMETHODINVESTMENTS</Role>
      <ShortName>VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9952170 - Disclosure - REDEEMABLE NON-CONTROLLING INTERESTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REDEEMABLENONCONTROLLINGINTERESTS</Role>
      <ShortName>REDEEMABLE NON-CONTROLLING INTERESTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9952171 - Disclosure - EARNINGS PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/EARNINGSPERSHARE</Role>
      <ShortName>EARNINGS PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9952172 - Disclosure - STOCK-BASED COMPENSATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/STOCKBASEDCOMPENSATION</Role>
      <ShortName>STOCK-BASED COMPENSATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9952173 - Disclosure - BUSINESS SEGMENT INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/BUSINESSSEGMENTINFORMATION</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9952174 - Disclosure - OTHER EXPENSES (INCOME), NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/OTHEREXPENSESINCOMENET</Role>
      <ShortName>OTHER EXPENSES (INCOME), NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9952175 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUBSEQUENTEVENTS</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESTables</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSTables</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERS</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - GOODWILL AND INTANGIBLE ASSETS, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/GOODWILLANDINTANGIBLEASSETSNETTables</Role>
      <ShortName>GOODWILL AND INTANGIBLE ASSETS, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/GOODWILLANDINTANGIBLEASSETSNET</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - ENERGY ASSETS, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/ENERGYASSETSNETTables</Role>
      <ShortName>ENERGY ASSETS, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/ENERGYASSETSNET</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - LEASES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/LEASESTables</Role>
      <ShortName>LEASES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/LEASES</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - DEBT AND FINANCING LEASE LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DEBTANDFINANCINGLEASELIABILITIESTables</Role>
      <ShortName>DEBT AND FINANCING LEASE LIABILITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/DEBTANDFINANCINGLEASELIABILITIES</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - FAIR VALUE MEASUREMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/FAIRVALUEMEASUREMENTTables</Role>
      <ShortName>FAIR VALUE MEASUREMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/FAIRVALUEMEASUREMENT</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESTables</Role>
      <ShortName>DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIES</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/VARIABLEINTERESTENTITIESANDEQUITYMETHODINVESTMENTSTables</Role>
      <ShortName>VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/VARIABLEINTERESTENTITIESANDEQUITYMETHODINVESTMENTS</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - EARNINGS PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/EARNINGSPERSHARETables</Role>
      <ShortName>EARNINGS PER SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/EARNINGSPERSHARE</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - STOCK-BASED COMPENSATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/STOCKBASEDCOMPENSATIONTables</Role>
      <ShortName>STOCK-BASED COMPENSATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/STOCKBASEDCOMPENSATION</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - BUSINESS SEGMENT INFORMATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/BUSINESSSEGMENTINFORMATIONTables</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/BUSINESSSEGMENTINFORMATION</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - OTHER EXPENSES (INCOME), NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/OTHEREXPENSESINCOMENETTables</Role>
      <ShortName>OTHER EXPENSES (INCOME), NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/OTHEREXPENSESINCOMENET</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Allowance for Credit Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAllowanceforCreditLossesDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Allowance for Credit Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Prepaid Expenses and Other Current Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPrepaidExpensesandOtherCurrentAssetsDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Prepaid Expenses and Other Current Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAdditionalInformationDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSDisaggregationofRevenueDetails</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS - Contract Balances (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSContractBalancesDetails</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS - Contract Balances (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSAdditionalInformationDetails</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS - Performance Obligation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSPerformanceObligationDetails</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS - Performance Obligation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - BUSINESS ACQUISITIONS AND RELATED TRANSACTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/BUSINESSACQUISITIONSANDRELATEDTRANSACTIONSDetails</Role>
      <ShortName>BUSINESS ACQUISITIONS AND RELATED TRANSACTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/BUSINESSACQUISITIONSANDRELATEDTRANSACTIONS</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - GOODWILL AND INTANGIBLE ASSETS, NET - Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/GOODWILLANDINTANGIBLEASSETSNETGoodwillDetails</Role>
      <ShortName>GOODWILL AND INTANGIBLE ASSETS, NET - Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - GOODWILL AND INTANGIBLE ASSETS, NET - Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/GOODWILLANDINTANGIBLEASSETSNETIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL AND INTANGIBLE ASSETS, NET - Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - GOODWILL AND INTANGIBLE ASSETS, NET - Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/GOODWILLANDINTANGIBLEASSETSNETAmortizationExpenseDetails</Role>
      <ShortName>GOODWILL AND INTANGIBLE ASSETS, NET - Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - ENERGY ASSETS, NET - Energy Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/ENERGYASSETSNETEnergyAssetsDetails</Role>
      <ShortName>ENERGY ASSETS, NET - Energy Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - ENERGY ASSETS, NET - Depreciation and Amortization Expense of Energy Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/ENERGYASSETSNETDepreciationandAmortizationExpenseofEnergyAssetsDetails</Role>
      <ShortName>ENERGY ASSETS, NET - Depreciation and Amortization Expense of Energy Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - ENERGY ASSETS, NET - Capitalized Interest (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/ENERGYASSETSNETCapitalizedInterestDetails</Role>
      <ShortName>ENERGY ASSETS, NET - Capitalized Interest (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - ENERGY ASSETS, NET - Asset And Liabilities Retirement Obligations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/ENERGYASSETSNETAssetAndLiabilitiesRetirementObligationsDetails</Role>
      <ShortName>ENERGY ASSETS, NET - Asset And Liabilities Retirement Obligations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9955540 - Disclosure - LEASES - Supplemental Balance Sheet Information Related to Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/LEASESSupplementalBalanceSheetInformationRelatedtoLeasesDetails</Role>
      <ShortName>LEASES - Supplemental Balance Sheet Information Related to Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9955541 - Disclosure - LEASES - Lease Cost (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/LEASESLeaseCostDetails</Role>
      <ShortName>LEASES - Lease Cost (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9955542 - Disclosure - LEASES - Supplemental Cash Flows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/LEASESSupplementalCashFlowsDetails</Role>
      <ShortName>LEASES - Supplemental Cash Flows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9955543 - Disclosure - LEASES - Minimum Future Lease Obligations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/LEASESMinimumFutureLeaseObligationsDetails</Role>
      <ShortName>LEASES - Minimum Future Lease Obligations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9955544 - Disclosure - LEASES - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/LEASESAdditionalInformationDetails</Role>
      <ShortName>LEASES - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9955545 - Disclosure - DEBT AND FINANCING LEASE LIABILITIES - Long-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DEBTANDFINANCINGLEASELIABILITIESLongtermDebtDetails</Role>
      <ShortName>DEBT AND FINANCING LEASE LIABILITIES - Long-term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9955546 - Disclosure - DEBT AND FINANCING LEASE LIABILITIES - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DEBTANDFINANCINGLEASELIABILITIESAdditionalInformationDetails</Role>
      <ShortName>DEBT AND FINANCING LEASE LIABILITIES - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9955547 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/INCOMETAXESDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/INCOMETAXES</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9955548 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/COMMITMENTSANDCONTINGENCIESDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/COMMITMENTSANDCONTINGENCIES</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9955549 - Disclosure - FAIR VALUE MEASUREMENT - Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/FAIRVALUEMEASUREMENTFairValueofAssetsandLiabilitiesMeasuredonaRecurringBasisDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENT - Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9955550 - Disclosure - FAIR VALUE MEASUREMENT - Changes in Contingent Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/FAIRVALUEMEASUREMENTChangesinContingentLiabilitiesDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENT - Changes in Contingent Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>9955551 - Disclosure - FAIR VALUE MEASUREMENT - Fair Value and Carrying Value of Long-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/FAIRVALUEMEASUREMENTFairValueandCarryingValueofLongtermDebtDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENT - Fair Value and Carrying Value of Long-term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>9955552 - Disclosure - FAIR VALUE MEASUREMENT - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/FAIRVALUEMEASUREMENTAdditionalInformationDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENT - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>9955553 - Disclosure - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Fair Value of Derivative Instruments on the Balance Sheet (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESFairValueofDerivativeInstrumentsontheBalanceSheetDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Fair Value of Derivative Instruments on the Balance Sheet (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>9955554 - Disclosure - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Effects on Statements of Income and Consolidated Statements of Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESEffectsonStatementsofIncomeandConsolidatedStatementsofComprehensiveIncomeDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Effects on Statements of Income and Consolidated Statements of Comprehensive Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>9955555 - Disclosure - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Effects of Derivative Instruments in Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESEffectsofDerivativeInstrumentsinAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Effects of Derivative Instruments in Accumulated Other Comprehensive Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>9955556 - Disclosure - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Active Derivative Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESActiveDerivativeInstrumentsDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Active Derivative Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>9955557 - Disclosure - VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Variable Interest Entity Financial Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/VARIABLEINTERESTENTITIESANDEQUITYMETHODINVESTMENTSVariableInterestEntityFinancialInformationDetails</Role>
      <ShortName>VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Variable Interest Entity Financial Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>9955558 - Disclosure - VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/VARIABLEINTERESTENTITIESANDEQUITYMETHODINVESTMENTSAdditionalInformationDetails</Role>
      <ShortName>VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>9955559 - Disclosure - VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Investment in Joint Ventures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/VARIABLEINTERESTENTITIESANDEQUITYMETHODINVESTMENTSInvestmentinJointVenturesDetails</Role>
      <ShortName>VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Investment in Joint Ventures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>9955560 - Disclosure - REDEEMABLE NON-CONTROLLING INTERESTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/REDEEMABLENONCONTROLLINGINTERESTSDetails</Role>
      <ShortName>REDEEMABLE NON-CONTROLLING INTERESTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/REDEEMABLENONCONTROLLINGINTERESTS</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>9955561 - Disclosure - EARNINGS PER SHARE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/EARNINGSPERSHAREDetails</Role>
      <ShortName>EARNINGS PER SHARE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/EARNINGSPERSHARETables</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>9955562 - Disclosure - STOCK-BASED COMPENSATION - Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/STOCKBASEDCOMPENSATIONCompensationExpenseDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION - Compensation Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>9955563 - Disclosure - STOCK-BASED COMPENSATION - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/STOCKBASEDCOMPENSATIONAdditionalInformationDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>9955564 - Disclosure - BUSINESS SEGMENT INFORMATION - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/BUSINESSSEGMENTINFORMATIONAdditionalInformationDetails</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>9955565 - Disclosure - BUSINESS SEGMENT INFORMATION - Segment Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/BUSINESSSEGMENTINFORMATIONSegmentInformationDetails</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION - Segment Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>9955566 - Disclosure - OTHER EXPENSES (INCOME), NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/OTHEREXPENSESINCOMENETDetails</Role>
      <ShortName>OTHER EXPENSES (INCOME), NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/OTHEREXPENSESINCOMENETTables</ParentRole>
      <Position>83</Position>
    </Report>
    <Report instance="amrc-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>9955567 - Disclosure - SUBSEQUENT EVENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ameresco.com/role/SUBSEQUENTEVENTDetails</Role>
      <ShortName>SUBSEQUENT EVENT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ameresco.com/role/SUBSEQUENTEVENTS</ParentRole>
      <Position>84</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-Q" isDefinitelyFs="true" isUsgaap="true" original="amrc-20260331.htm">amrc-20260331.htm</File>
    <File>amrc-20260331.xsd</File>
    <File>amrc-20260331_cal.xml</File>
    <File>amrc-20260331_def.xml</File>
    <File>amrc-20260331_lab.xml</File>
    <File>amrc-20260331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="1075">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="31">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
