| IRS990/AccountantCompileOrReviewInd | 0 | false |
| IRS990/AccountsReceivableGrp/BOYAmt | 0 | 2952923 |
| IRS990/AccountsReceivableGrp/EOYAmt | 0 | 0 |
| IRS990/ActivitiesConductedPrtshpInd | 0 | false |
| IRS990/ActivityOrMissionDesc | 0 | MAINTAIN AND OPERATE A MUSEUM AND NATURE TRAILS AND SANCTUARY PROPERTIES ON FISHERS ISLAND, NEW YORK. |
| IRS990/AdvertisingGrp/TotalAmt | 0 | 0 |
| IRS990/AllOtherExpensesGrp/TotalAmt | 0 | 0 |
| IRS990/BackupWthldComplianceInd | 0 | true |
| IRS990/BenefitsToMembersGrp/TotalAmt | 0 | 0 |
| IRS990/BooksInCareOfDetail/PersonNm | 0 | Pierce Rafferty |
| IRS990/BooksInCareOfDetail/PhoneNum | 0 | 6317887239 |
| IRS990/BooksInCareOfDetail/USAddress/AddressLine1Txt | 0 | PO Box 554 |
| IRS990/BooksInCareOfDetail/USAddress/CityNm | 0 | Fishers Island |
| IRS990/BooksInCareOfDetail/USAddress/StateAbbreviationCd | 0 | NY |
| IRS990/BooksInCareOfDetail/USAddress/ZIPCd | 0 | 06390 |
| IRS990/BusinessRlnWith35CtrlEntInd | 0 | false |
| IRS990/BusinessRlnWithFamMemInd | 0 | false |
| IRS990/BusinessRlnWithOrgMemInd | 0 | false |
| IRS990/CashNonInterestBearingGrp/EOYAmt | 0 | 2952923 |
| IRS990/ChangeToOrgDocumentsInd | 0 | false |
| IRS990/CntrctRcvdGreaterThan100KCnt | 0 | 0 |
| IRS990/CollectionsOfArtInd | 0 | true |
| IRS990/CompCurrentOfcrDirectorsGrp/TotalAmt | 0 | 0 |
| IRS990/CompDisqualPersonsGrp/TotalAmt | 0 | 0 |
| IRS990/CompensationFromOtherSrcsInd | 0 | false |
| IRS990/CompensationProcessCEOInd | 0 | false |
| IRS990/CompensationProcessOtherInd | 0 | true |
| IRS990/ConferencesMeetingsGrp/TotalAmt | 0 | 0 |
| IRS990/ConflictOfInterestPolicyInd | 0 | false |
| IRS990/ConservationEasementsInd | 0 | true |
| IRS990/ConsolidatedAuditFinclStmtInd | 0 | false |
| IRS990/CreditCounselingInd | 0 | false |
| IRS990/CYBenefitsPaidToMembersAmt | 0 | 0 |
| IRS990/CYContributionsGrantsAmt | 0 | 0 |
| IRS990/CYGrantsAndSimilarPaidAmt | 0 | 0 |
| IRS990/CYInvestmentIncomeAmt | 0 | 0 |
| IRS990/CYOtherExpensesAmt | 0 | 67650 |
| IRS990/CYOtherRevenueAmt | 0 | 0 |
| IRS990/CYProgramServiceRevenueAmt | 0 | 0 |
| IRS990/CYRevenuesLessExpensesAmt | 0 | -67650 |
| IRS990/CYSalariesCompEmpBnftPaidAmt | 0 | 0 |
| IRS990/CYTotalExpensesAmt | 0 | 67650 |
| IRS990/CYTotalFundraisingExpenseAmt | 0 | 0 |
| IRS990/CYTotalProfFndrsngExpnsAmt | 0 | 0 |
| IRS990/CYTotalRevenueAmt | 0 | 0 |
| IRS990/DecisionsSubjectToApprovaInd | 0 | false |
| IRS990/DeductibleArtContributionInd | 0 | false |
| IRS990/DeductibleNonCashContriInd | 0 | false |
| IRS990/DelegationOfMgmtDutiesInd | 0 | false |
| IRS990/DepreciationDepletionGrp/ProgramServicesAmt | 0 | 67650 |
| IRS990/DepreciationDepletionGrp/TotalAmt | 0 | 67650 |
| IRS990/Desc | 0 | MAINTAIN AND OPERATE A MUSEUM ON FISHERS ISLAND DISPLAYING COLLECTIONS PERTAINING TO LOCAL FLORA AND FAUNA, HISTORY AND ARCHAEOLOGY FOR THE EDUCATION AND BENEFIT OF THE GENERAL PUBLIC WITHOUT CHARGE. |
| IRS990/DescribedInSection501c3Ind | 0 | true |
| IRS990/DisregardedEntityInd | 0 | false |
| IRS990/DocumentRetentionPolicyInd | 0 | false |
| IRS990/DonorAdvisedFundInd | 0 | false |
| IRS990/DonorRstrOrQuasiEndowmentsInd | 0 | false |
| IRS990/ElectionOfBoardMembersInd | 0 | false |
| IRS990/EmployeeCnt | 0 | 3 |
| IRS990/EmploymentTaxReturnsFiledInd | 0 | true |
| IRS990/EngagedInExcessBenefitTransInd | 0 | false |
| IRS990/ExpenseAmt | 0 | 67650 |
| IRS990/FamilyOrBusinessRlnInd | 0 | true |
| IRS990/FederalGrantAuditRequiredInd | 0 | false |
| IRS990/FeesForServicesAccountingGrp/TotalAmt | 0 | 0 |
| IRS990/FeesForServicesLegalGrp/TotalAmt | 0 | 0 |
| IRS990/FeesForServicesLobbyingGrp/TotalAmt | 0 | 0 |
| IRS990/FeesForServicesManagementGrp/TotalAmt | 0 | 0 |
| IRS990/FeesForServicesOtherGrp/TotalAmt | 0 | 0 |
| IRS990/FeesForServicesProfFundraising/TotalAmt | 0 | 0 |
| IRS990/FeesForSrvcInvstMgmntFeesGrp/TotalAmt | 0 | 0 |
| IRS990/ForeignActivitiesInd | 0 | false |
| IRS990/ForeignFinancialAccountInd | 0 | false |
| IRS990/ForeignGrantsGrp/TotalAmt | 0 | 0 |
| IRS990/ForeignOfficeInd | 0 | false |
| IRS990/Form1098CFiledInd | 0 | false |
| IRS990/Form8282FiledCnt | 0 | 0 |
| IRS990/Form8282PropertyDisposedOfInd | 0 | false |
| IRS990/Form8899Filedind | 0 | false |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 0 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 1 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 2 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 3 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 4 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 5 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 6 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 7 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 8 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 9 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 10 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 11 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 12 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 13 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 14 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 15 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 16 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 17 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 18 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 19 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRltdOrgRt | 20 | 0.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 0 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 1 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 2 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 3 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 4 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 5 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 6 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 7 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 8 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 9 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 10 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 11 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 12 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 13 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 14 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 15 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 16 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 17 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 18 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 19 | 1.20 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 20 | 40.00 |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 0 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 1 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 2 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 3 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 4 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 5 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 6 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 7 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 8 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 9 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 10 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 11 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 12 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 13 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 14 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 15 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 16 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 17 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 18 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 19 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 0 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 1 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 2 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 3 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 4 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 5 | X |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 0 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 1 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 2 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 3 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 4 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 5 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 6 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 7 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 8 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 9 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 10 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 11 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 12 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 13 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 14 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 15 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 16 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 17 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 18 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 19 | 0 |
| IRS990/Form990PartVIISectionAGrp/OtherCompensationAmt | 20 | 0 |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 0 | Elizabeth McCance |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 1 | L Bagley Reid |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 2 | Robert J Miller |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 3 | B Scott Reid |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 4 | Henry L Ferguson III |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 5 | Marion Ferguson Briggs |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 6 | Barry Bryan |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 7 | Heather F Burnham |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 8 | Carrie Coolidge |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 9 | Jeffrey Edwards |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 10 | Ken Edwards Sr |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 11 | Audrey Ludemann |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 12 | Steve Malinowski |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 13 | Terry McNamara |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 14 | Wendy O'Neil |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 15 | Thomas Parker |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 16 | Megan Bohlen Raymond |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 17 | Barbara C Riegel |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 18 | Eugenie Trevor |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 19 | Alice Cary Brown |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 20 | Pierce Rafferty |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 0 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 1 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 2 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 3 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 4 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 5 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 6 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 7 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 8 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 9 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 10 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 11 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 12 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 13 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 14 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 15 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 16 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 17 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 18 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 19 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromOrgAmt | 20 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 0 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 1 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 2 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 3 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 4 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 5 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 6 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 7 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 8 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 9 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 10 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 11 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 12 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 13 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 14 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 15 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 16 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 17 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 18 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 19 | 0 |
| IRS990/Form990PartVIISectionAGrp/ReportableCompFromRltdOrgAmt | 20 | 0 |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 0 | President |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 1 | Vice President |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 2 | V. Pres - Land |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 3 | Treasurer |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 4 | Secretary |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 5 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 6 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 7 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 8 | BOARD MEMBER |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 9 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 10 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 11 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 12 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 13 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 14 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 15 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 16 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 17 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 18 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 19 | Board Member |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 20 | Executive Dir. |
| IRS990/Form990ProvidedToGvrnBodyInd | 0 | true |
| IRS990/FormationYr | 0 | 1967 |
| IRS990/FormerOfcrEmployeesListedInd | 0 | false |
| IRS990/FSAuditedInd | 0 | false |
| IRS990/FundraisingActivitiesInd | 0 | false |
| IRS990/GamingActivitiesInd | 0 | false |
| IRS990/GoverningBodyVotingMembersCnt | 0 | 20 |
| IRS990/GrantsToDomesticIndividualsGrp/TotalAmt | 0 | 0 |
| IRS990/GrantsToDomesticOrgsGrp/TotalAmt | 0 | 0 |
| IRS990/GrantsToIndividualsInd | 0 | false |
| IRS990/GrantsToOrganizationsInd | 0 | false |
| IRS990/GrantToRelatedPersonInd | 0 | false |
| IRS990/GrossReceiptsAmt | 0 | 0 |
| IRS990/GroupReturnForAffiliatesInd | 0 | false |
| IRS990/IncludeFIN48FootnoteInd | 0 | false |
| IRS990/IncmFromInvestBondProceedsGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/IndependentAuditFinclStmtInd | 0 | false |
| IRS990/IndependentVotingMemberCnt | 0 | 20 |
| IRS990/IndivRcvdGreaterThan100KCnt | 0 | 0 |
| IRS990/IndoorTanningServicesInd | 0 | false |
| IRS990/InfoInScheduleOPartVIInd | 0 | X |
| IRS990/InformationTechnologyGrp/TotalAmt | 0 | 0 |
| IRS990/InsuranceGrp/TotalAmt | 0 | 0 |
| IRS990/IntangibleAssetsGrp/EOYAmt | 0 | 0 |
| IRS990/InterestGrp/TotalAmt | 0 | 0 |
| IRS990/InventoriesForSaleOrUseGrp/EOYAmt | 0 | 0 |
| IRS990/InvestmentIncomeGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/InvestmentInJointVentureInd | 0 | false |
| IRS990/InvestmentsOtherSecuritiesGrp/EOYAmt | 0 | 0 |
| IRS990/InvestmentsProgramRelatedGrp/EOYAmt | 0 | 0 |
| IRS990/InvestmentsPubTradedSecGrp/EOYAmt | 0 | 0 |
| IRS990/IRPDocumentCnt | 0 | 9 |
| IRS990/IRPDocumentW2GCnt | 0 | 0 |
| IRS990/LandBldgEquipAccumDeprecAmt | 0 | 927976 |
| IRS990/LandBldgEquipBasisNetGrp/BOYAmt | 0 | 9910035 |
| IRS990/LandBldgEquipBasisNetGrp/EOYAmt | 0 | 9842385 |
| IRS990/LandBldgEquipCostOrOtherBssAmt | 0 | 10770361 |
| IRS990/LegalDomicileStateCd | 0 | NY |
| IRS990/LoanOutstandingInd | 0 | false |
| IRS990/LobbyingActivitiesInd | 0 | false |
| IRS990/LocalChaptersInd | 0 | false |
| IRS990/MaterialDiversionOrMisuseInd | 0 | false |
| IRS990/MembersOrStockholdersInd | 0 | false |
| IRS990/MethodOfAccountingCashInd | 0 | X |
| IRS990/MinutesOfCommitteesInd | 0 | true |
| IRS990/MinutesOfGoverningBodyInd | 0 | true |
| IRS990/MissionDesc | 0 | MAINTAIN AND OPERATE A MUSEUM AND NATURE TRAILS AND SANCTUARY PROPERTIES ON FISHERS ISLAND, NEW YORK. |
| IRS990/MoreThan5000KToIndividualsInd | 0 | false |
| IRS990/MoreThan5000KToOrgInd | 0 | false |
| IRS990/NetAssetsOrFundBalancesBOYAmt | 0 | 12862958 |
| IRS990/NetAssetsOrFundBalancesEOYAmt | 0 | 12795308 |
| IRS990/NetGainOrLossInvestmentsGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetIncmFromFundraisingEvtGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetIncomeFromGamingGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetIncomeOrLossGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetRentalIncomeOrLossGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NoDonorRestrictionNetAssetsGrp/BOYAmt | 0 | 12862958 |
| IRS990/NoDonorRestrictionNetAssetsGrp/EOYAmt | 0 | 12795308 |
| IRS990/NoListedPersonsCompensatedInd | 0 | X |
| IRS990/NondeductibleContributionsInd | 0 | false |
| IRS990/OccupancyGrp/TotalAmt | 0 | 0 |
| IRS990/OfficeExpensesGrp/TotalAmt | 0 | 0 |
| IRS990/OfficerMailingAddressInd | 0 | false |
| IRS990/OperateHospitalInd | 0 | false |
| IRS990/Organization501c3Ind | 0 | X |
| IRS990/OrganizationFollowsFASB117Ind | 0 | X |
| IRS990/OtherAssetsTotalGrp/EOYAmt | 0 | 0 |
| IRS990/OtherEmployeeBenefitsGrp/TotalAmt | 0 | 0 |
| IRS990/OtherRevenueMiscGrp/Desc | 0 | Miscellaneous Revenue |
| IRS990/OtherRevenueTotalAmt | 0 | 0 |
| IRS990/OtherSalariesAndWagesGrp/TotalAmt | 0 | 0 |
| IRS990/OtherWebsiteInd | 0 | X |
| IRS990/OthNotesLoansReceivableNetGrp/EOYAmt | 0 | 0 |
| IRS990/PartialLiquidationInd | 0 | false |
| IRS990/PaymentsToAffiliatesGrp/TotalAmt | 0 | 0 |
| IRS990/PayPremiumsPrsnlBnftCntrctInd | 0 | false |
| IRS990/PayrollTaxesGrp/TotalAmt | 0 | 0 |
| IRS990/PensionPlanContributionsGrp/TotalAmt | 0 | 0 |
| IRS990/PledgesAndGrantsReceivableGrp/EOYAmt | 0 | 0 |
| IRS990/PoliticalCampaignActyInd | 0 | false |
| IRS990/PrepaidExpensesDefrdChargesGrp/EOYAmt | 0 | 0 |
| IRS990/ProfessionalFundraisingInd | 0 | false |
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