3.23.1 html 41 67 1 true 40 0 false 4 false false R1.htm 995470 - Disclosure - N-2 Sheet http://xbrl.sec.gov/cef/role/N2 N-2 Cover 1 false false All Reports Book All Reports [dq-0542-Deprecated-Concept] Concept SecurityAxis in cef/2022 used in 62 facts was deprecated in cef/2023 as of 2023-01-31 and should not be used. fp0083334-1_486bposixbrl.htm 2008, 2009, 2010, 2011, 2015, 2016, 2017, 2018, 2034, 2035, 2036, 2037, 2041, 2042, 2043, 2044, 2055, 2056, 2057, 2058, 2062, 2063, 2064, 2065, 2069, 2070, 2071, 2072, 2076, 2077, 2078, 2079, 2083, 2084, 2085, 2086, 2090, 2091, 2092, 2093, 2157, 2158, 2159, 2160, 2163, 2164, 2165, 2166, 2169, 2170, 2171, 2172, 2175, 2176, 2177, 2178, 4943, 4944, 4948, 4953, 4958, 4959 [dq-0555-ApproximateDateOfCommencementOfProposedSaleToThePublic-Missing] Submission type 486BPOS should have a non-empty value for ApproximateDateOfCommencementOfProposedSaleToThePublic in the Required Context. fp0083334-1_486bposixbrl.htm [ix-0514-Hidden-Fact-Eligible-For-Transform] WARN: 14 fact(s) appearing in ix:hidden were eligible for transformation: cef:BusinessDevelopmentCompanyFlag, cef:NewCefOrBdcRegistrantFlag, cef:PrimaryShelfFlag, cef:PrimaryShelfQualifiedFlag, dei:AdditionalSecurities462b, dei:AdditionalSecuritiesEffective413b, dei:DelayedOrContinuousOffering, dei:DividendOrInterestReinvestmentPlanOnly, dei:EffectiveAfter60Days486a, dei:EffectiveUponFiling462e, dei:EffectiveUponFiling486b, dei:EffectiveWhenDeclaredSection8c, dei:EntityEmergingGrowthCompany, dei:NewEffectiveDateForPreviousFiling - fp0083334-1_486bposixbrl.htm 25, 26, 27, 28, 29, 30, 31, 32, 34, 35, 38, 39, 41, 42 fp0083334-1_486bposixbrl.htm eiof-20230430.xsd eiof-20230430_def.xml eiof-20230430_lab.xml eiof-20230430_pre.xml fp0083334-1_ex99252b.htm fp0083334-1_ex99252l2.htm fp0083334-1_ex99252n.htm http://xbrl.sec.gov/cef/2022 http://xbrl.sec.gov/dei/2022 true false