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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Joseph S Cheng</PersonNm>
        <TitleTxt>Director-at-Large</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Michael Schulder</PersonNm>
        <TitleTxt>Director-at-Large</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Marjorie C Wang</PersonNm>
        <TitleTxt>Director-at-Large</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Kenneth S Blumenfeld</PersonNm>
        <TitleTxt>SW Regional Director</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Mark R Iantosca</PersonNm>
        <TitleTxt>NE Regional Director</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Ann M Parr</PersonNm>
        <TitleTxt>NW Regional Director</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Sharon Woods Webb</PersonNm>
        <TitleTxt>SE Regional Director</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Curtis J Rozzelle</PersonNm>
        <TitleTxt>SE Regional Director (Until 4/17/21)</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Andrew E Wakefield</PersonNm>
        <TitleTxt>NE Regional Director (Until 4/17/21)</TitleTxt>
        <AverageHoursPerWeekRt>5.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>5.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
        <ReportableCompFromOrgAmt>0</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Kathleen T Craig</PersonNm>
        <TitleTxt>Chief Executive Officer</TitleTxt>
        <AverageHoursPerWeekRt>15.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>35.00</AverageHoursPerWeekRltdOrgRt>
        <OfficerInd>X</OfficerInd>
        <ReportableCompFromOrgAmt>396540</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>42482</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Dennis J Rizzo</PersonNm>
        <TitleTxt>CFO</TitleTxt>
        <AverageHoursPerWeekRt>15.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>35.00</AverageHoursPerWeekRltdOrgRt>
        <OfficerInd>X</OfficerInd>
        <ReportableCompFromOrgAmt>187981</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>49023</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Katherine O Orrico</PersonNm>
        <TitleTxt>Washington Office Director</TitleTxt>
        <AverageHoursPerWeekRt>50.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
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        <ReportableCompFromOrgAmt>282212</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>51481</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Anthony P Macalindong</PersonNm>
        <TitleTxt>Director of Info Services</TitleTxt>
        <AverageHoursPerWeekRt>38.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
        <KeyEmployeeInd>X</KeyEmployeeInd>
        <ReportableCompFromOrgAmt>178923</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>28914</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Kathryn A Dattomo</PersonNm>
        <TitleTxt>Chief Development Officer</TitleTxt>
        <AverageHoursPerWeekRt>38.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
        <HighestCompensatedEmployeeInd>X</HighestCompensatedEmployeeInd>
        <ReportableCompFromOrgAmt>160894</ReportableCompFromOrgAmt>
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        <OtherCompensationAmt>21984</OtherCompensationAmt>
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      <Form990PartVIISectionAGrp>
        <PersonNm>Cathy J Hill</PersonNm>
        <TitleTxt>Manager, Regulatory Affairs</TitleTxt>
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        <OtherCompensationAmt>30056</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>Elizabeth A Sartore</PersonNm>
        <TitleTxt>Associate Executive Director</TitleTxt>
        <AverageHoursPerWeekRt>38.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
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        <OtherCompensationAmt>50170</OtherCompensationAmt>
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      <Form990PartVIISectionAGrp>
        <PersonNm>Adrienne R Mortimer</PersonNm>
        <TitleTxt>Senior Manager - Legal Affairs</TitleTxt>
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        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
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      <Form990PartVIISectionAGrp>
        <PersonNm>Alice I Kelsey</PersonNm>
        <TitleTxt>AED - Mkt &amp; Comm</TitleTxt>
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        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
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        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>26237</OtherCompensationAmt>
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      <TotReportableCompRltdOrgAmt>0</TotReportableCompRltdOrgAmt>
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      <CntrctRcvdGreaterThan100KCnt>0</CntrctRcvdGreaterThan100KCnt>
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      <ProgramServiceRevenueGrp>
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        <Desc>Annual Dues</Desc>
        <BusinessCd>900099</BusinessCd>
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      <ProgramServiceRevenueGrp>
        <Desc>Annual Meeting</Desc>
        <BusinessCd>541800</BusinessCd>
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        <Desc>Joint Programs</Desc>
        <BusinessCd>900099</BusinessCd>
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        <ExclusionAmt>380438</ExclusionAmt>
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        <ExclusionAmt>41720</ExclusionAmt>
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        <RealAmt>86638</RealAmt>
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      <RentalIncomeOrLossGrp>
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        <ExclusionAmt>58247</ExclusionAmt>
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        <SecuritiesAmt>4770859</SecuritiesAmt>
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      <LessCostOthBasisSalesExpnssGrp>
        <SecuritiesAmt>3698151</SecuritiesAmt>
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      <GainOrLossGrp>
        <SecuritiesAmt>1072708</SecuritiesAmt>
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      <NetGainOrLossInvestmentsGrp>
        <TotalRevenueColumnAmt>1072708</TotalRevenueColumnAmt>
        <ExclusionAmt>1072708</ExclusionAmt>
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        <TotalRevenueColumnAmt>10342533</TotalRevenueColumnAmt>
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        <UnrelatedBusinessRevenueAmt>472073</UnrelatedBusinessRevenueAmt>
        <ExclusionAmt>1553113</ExclusionAmt>
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      <GrantsToDomesticOrgsGrp>
        <TotalAmt>15599</TotalAmt>
        <ProgramServicesAmt>15599</ProgramServicesAmt>
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      <GrantsToDomesticIndividualsGrp>
        <TotalAmt>61250</TotalAmt>
        <ProgramServicesAmt>61250</ProgramServicesAmt>
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        <TotalAmt>27750</TotalAmt>
        <ProgramServicesAmt>27750</ProgramServicesAmt>
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      <CompCurrentOfcrDirectorsGrp>
        <TotalAmt>1483907</TotalAmt>
        <ProgramServicesAmt>830988</ProgramServicesAmt>
        <ManagementAndGeneralAmt>652919</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>2702425</ProgramServicesAmt>
        <ManagementAndGeneralAmt>2123334</ManagementAndGeneralAmt>
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      <PensionPlanContributionsGrp>
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        <ProgramServicesAmt>153773</ProgramServicesAmt>
        <ManagementAndGeneralAmt>120822</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>691247</ProgramServicesAmt>
        <ManagementAndGeneralAmt>543123</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>184209</ProgramServicesAmt>
        <ManagementAndGeneralAmt>144736</ManagementAndGeneralAmt>
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        <ManagementAndGeneralAmt>291756</ManagementAndGeneralAmt>
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      <FeesForServicesLegalGrp>
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        <ManagementAndGeneralAmt>409248</ManagementAndGeneralAmt>
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      <FeesForServicesAccountingGrp>
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        <ManagementAndGeneralAmt>95835</ManagementAndGeneralAmt>
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        <ManagementAndGeneralAmt>119351</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>167781</ProgramServicesAmt>
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        <ProgramServicesAmt>55176</ProgramServicesAmt>
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        <ManagementAndGeneralAmt>38092</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>106660</ProgramServicesAmt>
        <ManagementAndGeneralAmt>83805</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>80956</ProgramServicesAmt>
        <ManagementAndGeneralAmt>39874</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>248961</ProgramServicesAmt>
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        <ProgramServicesAmt>351215</ProgramServicesAmt>
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        <ProgramServicesAmt>93981</ProgramServicesAmt>
        <ManagementAndGeneralAmt>73842</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>135687</ProgramServicesAmt>
        <ManagementAndGeneralAmt>66831</ManagementAndGeneralAmt>
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        <TotalAmt>78946</TotalAmt>
        <ManagementAndGeneralAmt>78946</ManagementAndGeneralAmt>
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        <ProgramServicesAmt>5956139</ProgramServicesAmt>
        <ManagementAndGeneralAmt>5456270</ManagementAndGeneralAmt>
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        <EOYAmt>2482712</EOYAmt>
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      <AccountsReceivableGrp>
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        <EOYAmt>5042569</EOYAmt>
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        <EOYAmt>72915</EOYAmt>
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        <BOYAmt>772436</BOYAmt>
        <EOYAmt>2332419</EOYAmt>
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        <EOYAmt>4906962</EOYAmt>
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        <EOYAmt>24651093</EOYAmt>
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        <EOYAmt>1821530</EOYAmt>
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        <BOYAmt>219136</BOYAmt>
        <EOYAmt>219136</EOYAmt>
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      <TotalAssetsGrp>
        <BOYAmt>32721045</BOYAmt>
        <EOYAmt>41529336</EOYAmt>
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      <AccountsPayableAccrExpnssGrp>
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        <EOYAmt>8938321</EOYAmt>
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      <DeferredRevenueGrp>
        <BOYAmt>2914110</BOYAmt>
        <EOYAmt>4683860</EOYAmt>
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      <UnsecuredNotesLoansPayableGrp>
        <BOYAmt>988845</BOYAmt>
        <EOYAmt>0</EOYAmt>
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      <OtherLiabilitiesGrp>
        <BOYAmt>927716</BOYAmt>
        <EOYAmt>739347</EOYAmt>
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      <TotalLiabilitiesGrp>
        <BOYAmt>10707438</BOYAmt>
        <EOYAmt>14361528</EOYAmt>
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      <OrganizationFollowsFASB117Ind>X</OrganizationFollowsFASB117Ind>
      <NoDonorRestrictionNetAssetsGrp>
        <BOYAmt>15891559</BOYAmt>
        <EOYAmt>21047788</EOYAmt>
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      <DonorRestrictionNetAssetsGrp>
        <BOYAmt>6122048</BOYAmt>
        <EOYAmt>6120020</EOYAmt>
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        <BOYAmt>22013607</BOYAmt>
        <EOYAmt>27167808</EOYAmt>
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      <TotLiabNetAssetsFundBalanceGrp>
        <BOYAmt>32721045</BOYAmt>
        <EOYAmt>41529336</EOYAmt>
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        <PersonNm>Cathy J Hill</PersonNm>
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        <PersonNm>Elizabeth A Sartore</PersonNm>
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        <PersonNm>Adrienne R Mortimer</PersonNm>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Section A, line 6</FormAndLineReferenceDesc>
        <ExplanationTxt>All Members of the American Association of Neurological Surgeons (AANS) shall be considered Members of American Association of Neurosurgeons (AAN). The Members elected to the AANS shall be divided into eleven classes: 1) Fellow 2) Provisional 3) International 4) Associate 5) Allied 6) Lifetime 7) Candidate 8) International Candidate 9) Honorary 10) Affiliate 11) Student Only Fellows, Provisional, and Lifetime Members may vote. Only Fellows may hold office.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Section A, line 7a</FormAndLineReferenceDesc>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Section B, line 11b</FormAndLineReferenceDesc>
        <ExplanationTxt>The Form 990 is reviewed within the Association's Accounting Department by the Accounting Manager and Chief Financial Officer. Input for Form 990 inclusion is submitted to the Association's tax preparer by the Accounting Department. After Form 990 is completed by the Association's tax preparer, the Form 990 is again reviewed by both the Accounting Manager and Chief Financial Officer prior to filing with the IRS.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Section B, line 12c</FormAndLineReferenceDesc>
        <ExplanationTxt>As a CME provider accredited by the ACCME, the AAN requires all individuals (and their significant others) in a position to influence and/or control the content of AAN directly and jointly sponsored CME activities to disclose to the AAN and subsequently to learners that the individual either has no relevant financial relationship or has any relevant financial relationships with a commercial interest. All disclosure information must be provided to AAN CME activity participants prior to the beginning of the CME activity. If a disclosure is not completed, the individual will not participate in the activity. All potential conflicts of interest identified through review of the disclosure form must be resolved in order for individuals in a position to influence and/or control CME content to be confirmed for the educational assignment. The resolution process and documents must be documented in the CME activity file. A conflict of interest disclosure must also be completed yearly by AAN Committee Members. Anyone who does not complete the disclosure will not participate on the Committee.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Section B, line 15a</FormAndLineReferenceDesc>
        <ExplanationTxt>The Chief Executive Officer's annual compensation is subject to the provisions in their employment contract: The Executive shall receive a base salary, paid in accordance with the Association's normal payroll practices. Effective as of January 1, 2021, the Executive's base salary shall be at an annual rate of $500,000, and shall increase three percent (3%) on January 1st of each year. In addition, during the period of November 1, 2018 through December 31, 2018, the Association and the Executives agree to meet in good faith to renegotiate the Executive's base salary to determine any other appropriate increase. The Association may award the Executive bonuses in such amounts and at such times as the Association's Review Committee, in his or her sole discretion, deems appropriate. This process is documented. Compensation for the CFO and Associate Executive Directors is determined by the Chief Executive Officer. The CEO's basis for determining compensation is based on market data including the Association Forum of Chicagoland.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Section C, line 19</FormAndLineReferenceDesc>
        <ExplanationTxt>The organization makes its governing documents, conflict of interest policy and financial statements available to the public upon request for the same period of disclosure as set forth in IRC Section 6104(d).</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part XI, line 9:</FormAndLineReferenceDesc>
        <ExplanationTxt>Transfer from American Association of Neurological Surgeons, Inc. 1,476,172.</ExplanationTxt>
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