3.3.1.900 html 474 504 1 true 155 0 false 4 false false R1.htm 0001000 - Document - Document and Entity Information Document Sheet http://www.itctransco.com/role/DocumentAndEntityInformationDocument Document and Entity Information Document Cover 1 false false R2.htm 1001000 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL POSITION Sheet http://www.itctransco.com/role/ConsolidatedStatementsOfFinancialPosition CONSOLIDATED STATEMENTS OF FINANCIAL POSITION Statements 2 false false R3.htm 1002500 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parentheticals) Sheet http://www.itctransco.com/role/ConsolidatedStatementsOfFinancialPositionParentheticals CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parentheticals) Statements 3 false false R4.htm 1003000 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS Sheet http://www.itctransco.com/role/ConsolidatedStatementsOfOperations CONSOLIDATED STATEMENTS OF OPERATIONS Statements 4 false false R5.htm 1004000 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Sheet http://www.itctransco.com/role/ConsolidatedStatementsOfComprehensiveIncome CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Statements 5 false false R6.htm 1006000 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY Sheet http://www.itctransco.com/role/ConsolidatedStatementsOfChangesInStockholdersEquity CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY Statements 6 false false R7.htm 1007500 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parentheticals) Sheet http://www.itctransco.com/role/ConsolidatedStatementsOfChangesInStockholdersEquityParentheticals CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parentheticals) Statements 7 false false R8.htm 1008000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS Sheet http://www.itctransco.com/role/ConsolidatedStatementsOfCashFlows CONSOLIDATED STATEMENTS OF CASH FLOWS Statements 8 false false R9.htm 2103100 - Disclosure - GENERAL Sheet http://www.itctransco.com/role/General GENERAL Notes 9 false false R10.htm 2104100 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES Sheet http://www.itctransco.com/role/SignificantAccountingPolicies SIGNIFICANT ACCOUNTING POLICIES Notes 10 false false R11.htm 2107100 - Disclosure - RECENT ACCOUNTING PRONOUNCEMENTS Sheet http://www.itctransco.com/role/RecentAccountingPronouncements RECENT ACCOUNTING PRONOUNCEMENTS Notes 11 false false R12.htm 2108100 - Disclosure - REGULATORY MATTERS Sheet http://www.itctransco.com/role/RegulatoryMatters REGULATORY MATTERS Notes 12 false false R13.htm 2110100 - Disclosure - REGULATORY ASSETS AND LIABILITIES Sheet http://www.itctransco.com/role/RegulatoryAssetsAndLiabilities REGULATORY ASSETS AND LIABILITIES Notes 13 false false R14.htm 2112100 - Disclosure - GOODWILL AND INTANGIBLE ASSETS Sheet http://www.itctransco.com/role/GoodwillAndIntangibleAssets GOODWILL AND INTANGIBLE ASSETS Notes 14 false false R15.htm 2114100 - Disclosure - PROPERTY, PLANT AND EQUIPMENT Sheet http://www.itctransco.com/role/PropertyPlantAndEquipment PROPERTY, PLANT AND EQUIPMENT Notes 15 false false R16.htm 2116100 - Disclosure - DEBT Sheet http://www.itctransco.com/role/Debt DEBT Notes 16 false false R17.htm 2119100 - Disclosure - EARNINGS PER SHARE Sheet http://www.itctransco.com/role/EarningsPerShare EARNINGS PER SHARE Notes 17 false false R18.htm 2120100 - Disclosure - INCOME TAXES Sheet http://www.itctransco.com/role/IncomeTaxes INCOME TAXES Notes 18 false false R19.htm 2122100 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrust RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Notes 19 false false R20.htm 2124100 - Disclosure - FAIR VALUE MEASUREMENTS Sheet http://www.itctransco.com/role/FairValueMeasurements FAIR VALUE MEASUREMENTS Notes 20 false false R21.htm 2126100 - Disclosure - STOCKHOLDERS EQUITY Sheet http://www.itctransco.com/role/StockholdersEquity STOCKHOLDERS EQUITY Notes 21 false false R22.htm 2127100 - Disclosure - SHARE-BASED COMPENSATION Sheet http://www.itctransco.com/role/ShareBasedCompensation SHARE-BASED COMPENSATION Notes 22 false false R23.htm 2128100 - Disclosure - JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES Sheet http://www.itctransco.com/role/JointlyOwnedUtilityPlantCoordinatedServices JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES Notes 23 false false R24.htm 2129100 - Disclosure - COMMITMENTS AND CONTINGENT LIABILITIES Sheet http://www.itctransco.com/role/CommitmentsAndContingentLiabilities COMMITMENTS AND CONTINGENT LIABILITIES Notes 24 false false R25.htm 2130100 - Disclosure - ENTERGY TRANSACTION Sheet http://www.itctransco.com/role/EntergyTransaction ENTERGY TRANSACTION Notes 25 false false R26.htm 2131100 - Disclosure - SEGMENT INFORMATION Sheet http://www.itctransco.com/role/SegmentInformation SEGMENT INFORMATION Notes 26 false false R27.htm 2132100 - Disclosure - SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (Unaudited) Sheet http://www.itctransco.com/role/SupplementaryQuarterlyFinancialInformationUnaudited SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (Unaudited) Notes 27 false false R28.htm 2134100 - Disclosure - SUBSEQUENT EVENTS Sheet http://www.itctransco.com/role/SubsequentEvents SUBSEQUENT EVENTS Notes 28 false false R29.htm 2135100 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrant SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Notes 29 false false R30.htm 2204201 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies) Sheet http://www.itctransco.com/role/SignificantAccountingPoliciesPolicies SIGNIFICANT ACCOUNTING POLICIES (Policies) Policies 30 false false R31.htm 2229201 - Disclosure - COMMITMENTS AND CONTINGENT LIABILITIES (Policies) Sheet http://www.itctransco.com/role/CommitmentsAndContingentLiabilitiesPolicies COMMITMENTS AND CONTINGENT LIABILITIES (Policies) Policies 31 false false R32.htm 2304302 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Tables) Sheet http://www.itctransco.com/role/SignificantAccountingPoliciesTables SIGNIFICANT ACCOUNTING POLICIES (Tables) Tables http://www.itctransco.com/role/SignificantAccountingPolicies 32 false false R33.htm 2308301 - Disclosure - REGULATORY MATTERS (Tables) Sheet http://www.itctransco.com/role/RegulatoryMattersTables REGULATORY MATTERS (Tables) Tables http://www.itctransco.com/role/RegulatoryMatters 33 false false R34.htm 2310301 - Disclosure - REGULATORY ASSETS AND LIABILITIES (Tables) Sheet http://www.itctransco.com/role/RegulatoryAssetsAndLiabilitiesTables REGULATORY ASSETS AND LIABILITIES (Tables) Tables http://www.itctransco.com/role/RegulatoryAssetsAndLiabilities 34 false false R35.htm 2312301 - Disclosure - GOODWILL AND INTANGIBLE ASSETS (Tables) Sheet http://www.itctransco.com/role/GoodwillAndIntangibleAssetsTables GOODWILL AND INTANGIBLE ASSETS (Tables) Tables http://www.itctransco.com/role/GoodwillAndIntangibleAssets 35 false false R36.htm 2314301 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Tables) Sheet http://www.itctransco.com/role/PropertyPlantAndEquipmentTables PROPERTY, PLANT AND EQUIPMENT (Tables) Tables http://www.itctransco.com/role/PropertyPlantAndEquipment 36 false false R37.htm 2316301 - Disclosure - DEBT (Tables) Sheet http://www.itctransco.com/role/DebtTables DEBT (Tables) Tables http://www.itctransco.com/role/Debt 37 false false R38.htm 2319301 - Disclosure - EARNINGS PER SHARE (Tables) Sheet http://www.itctransco.com/role/EarningsPerShareTables EARNINGS PER SHARE (Tables) Tables http://www.itctransco.com/role/EarningsPerShare 38 false false R39.htm 2320301 - Disclosure - INCOME TAXES (Tables) Sheet http://www.itctransco.com/role/IncomeTaxesTables INCOME TAXES (Tables) Tables http://www.itctransco.com/role/IncomeTaxes 39 false false R40.htm 2322301 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST (Tables) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustTables RETIREMENT BENEFITS AND ASSETS HELD IN TRUST (Tables) Tables http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrust 40 false false R41.htm 2324301 - Disclosure - FAIR VALUE MEASUREMENTS (Tables) Sheet http://www.itctransco.com/role/FairValueMeasurementsTables FAIR VALUE MEASUREMENTS (Tables) Tables http://www.itctransco.com/role/FairValueMeasurements 41 false false R42.htm 2326301 - Disclosure - STOCKHOLDERS' EQUITY (Tables) Sheet http://www.itctransco.com/role/StockholdersEquityTables STOCKHOLDERS' EQUITY (Tables) Tables 42 false false R43.htm 2327301 - Disclosure - SHARE-BASED COMPENSATION (Tables) Sheet http://www.itctransco.com/role/ShareBasedCompensationTables SHARE-BASED COMPENSATION (Tables) Tables http://www.itctransco.com/role/ShareBasedCompensation 43 false false R44.htm 2328301 - Disclosure - JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES (Tables) Sheet http://www.itctransco.com/role/JointlyOwnedUtilityPlantCoordinatedServicesTables JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES (Tables) Tables http://www.itctransco.com/role/JointlyOwnedUtilityPlantCoordinatedServices 44 false false R45.htm 2329302 - Disclosure - COMMITMENTS AND CONTINGENT LIABILITIES (Tables) Sheet http://www.itctransco.com/role/CommitmentsAndContingentLiabilitiesTables COMMITMENTS AND CONTINGENT LIABILITIES (Tables) Tables http://www.itctransco.com/role/CommitmentsAndContingentLiabilities 45 false false R46.htm 2331301 - Disclosure - SEGMENT INFORMATION (Tables) Sheet http://www.itctransco.com/role/SegmentInformationTables SEGMENT INFORMATION (Tables) Tables http://www.itctransco.com/role/SegmentInformation 46 false false R47.htm 2332301 - Disclosure - SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (Unaudited) (Tables) Sheet http://www.itctransco.com/role/SupplementaryQuarterlyFinancialInformationUnauditedTables SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (Unaudited) (Tables) Tables http://www.itctransco.com/role/SupplementaryQuarterlyFinancialInformationUnaudited 47 false false R48.htm 2404403 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES Supplementary Cash Flows Information (Details) Sheet http://www.itctransco.com/role/SignificantAccountingPoliciesSupplementaryCashFlowsInformationDetails SIGNIFICANT ACCOUNTING POLICIES Supplementary Cash Flows Information (Details) Details 48 false false R49.htm 2404404 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Details) Sheet http://www.itctransco.com/role/SignificantAccountingPoliciesDetails SIGNIFICANT ACCOUNTING POLICIES (Details) Details http://www.itctransco.com/role/SignificantAccountingPoliciesTables 49 false false R50.htm 2408402 - Disclosure - REGULATORY MATTERS Changes in Regulatory Assets and Liabilities (Details) Sheet http://www.itctransco.com/role/RegulatoryMattersChangesInRegulatoryAssetsAndLiabilitiesDetails REGULATORY MATTERS Changes in Regulatory Assets and Liabilities (Details) Details 50 false false R51.htm 2408403 - Disclosure - REGULATORY MATTERS Schedule of Regulatory Assets and Liabilities (Details) Sheet http://www.itctransco.com/role/RegulatoryMattersScheduleOfRegulatoryAssetsAndLiabilitiesDetails REGULATORY MATTERS Schedule of Regulatory Assets and Liabilities (Details) Details 51 false false R52.htm 2408404 - Disclosure - REGULATORY MATTERS Additional Information (Details) Sheet http://www.itctransco.com/role/RegulatoryMattersAdditionalInformationDetails REGULATORY MATTERS Additional Information (Details) Details 52 false false R53.htm 2410402 - Disclosure - REGULATORY ASSETS AND LIABILITIES Regulatory Assets (Details) Sheet http://www.itctransco.com/role/RegulatoryAssetsAndLiabilitiesRegulatoryAssetsDetails REGULATORY ASSETS AND LIABILITIES Regulatory Assets (Details) Details 53 false false R54.htm 2410403 - Disclosure - REGULATORY ASSETS AND LIABILITIES Regulatory Liabilities (Details) Sheet http://www.itctransco.com/role/RegulatoryAssetsAndLiabilitiesRegulatoryLiabilitiesDetails REGULATORY ASSETS AND LIABILITIES Regulatory Liabilities (Details) Details 54 false false R55.htm 2410404 - Disclosure - REGULATORY ASSETS AND LIABILITIES Additional Information (Details) Sheet http://www.itctransco.com/role/RegulatoryAssetsAndLiabilitiesAdditionalInformationDetails REGULATORY ASSETS AND LIABILITIES Additional Information (Details) Details 55 false false R56.htm 2412402 - Disclosure - GOODWILL AND INTANGIBLE ASSETS (Details) Sheet http://www.itctransco.com/role/GoodwillAndIntangibleAssetsDetails GOODWILL AND INTANGIBLE ASSETS (Details) Details http://www.itctransco.com/role/GoodwillAndIntangibleAssetsTables 56 false false R57.htm 2412403 - Disclosure - GOODWILL AND INTANGIBLE ASSETS Future Amortization Expense (Details) Sheet http://www.itctransco.com/role/GoodwillAndIntangibleAssetsFutureAmortizationExpenseDetails GOODWILL AND INTANGIBLE ASSETS Future Amortization Expense (Details) Details 57 false false R58.htm 2414402 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Details) Sheet http://www.itctransco.com/role/PropertyPlantAndEquipmentDetails PROPERTY, PLANT AND EQUIPMENT (Details) Details http://www.itctransco.com/role/PropertyPlantAndEquipmentTables 58 false false R59.htm 2416402 - Disclosure - DEBT Schedule of Debt (Details) Sheet http://www.itctransco.com/role/DebtScheduleOfDebtDetails DEBT Schedule of Debt (Details) Details 59 false false R60.htm 2416403 - Disclosure - DEBT Annual Maturities (Details) Sheet http://www.itctransco.com/role/DebtAnnualMaturitiesDetails DEBT Annual Maturities (Details) Details 60 false false R61.htm 2416404 - Disclosure - DEBT Interest Rate Swap Agreements (Details) Sheet http://www.itctransco.com/role/DebtInterestRateSwapAgreementsDetails DEBT Interest Rate Swap Agreements (Details) Details 61 false false R62.htm 2416405 - Disclosure - DEBT Revolving Credit Agreements (Details) Sheet http://www.itctransco.com/role/DebtRevolvingCreditAgreementsDetails DEBT Revolving Credit Agreements (Details) Details 62 false false R63.htm 2416406 - Disclosure - DEBT Additional Information (Details) Sheet http://www.itctransco.com/role/DebtAdditionalInformationDetails DEBT Additional Information (Details) Details 63 false false R64.htm 2419402 - Disclosure - EARNINGS PER SHARE Schedule of Basic and Diluted Earnings Per Common Share (Details) Sheet http://www.itctransco.com/role/EarningsPerShareScheduleOfBasicAndDilutedEarningsPerCommonShareDetails EARNINGS PER SHARE Schedule of Basic and Diluted Earnings Per Common Share (Details) Details 64 false false R65.htm 2419403 - Disclosure - EARNINGS PER SHARE Stock Split (Details) Sheet http://www.itctransco.com/role/EarningsPerShareStockSplitDetails EARNINGS PER SHARE Stock Split (Details) Details 65 false false R66.htm 2419404 - Disclosure - EARNINGS PER SHARE Additional Information (Details) Sheet http://www.itctransco.com/role/EarningsPerShareAdditionalInformationDetails EARNINGS PER SHARE Additional Information (Details) Details 66 false false R67.htm 2420402 - Disclosure - INCOME TAXES Income Tax Reconciliation (Details) Sheet http://www.itctransco.com/role/IncomeTaxesIncomeTaxReconciliationDetails INCOME TAXES Income Tax Reconciliation (Details) Details 67 false false R68.htm 2420403 - Disclosure - INCOME TAXES Components of Income Tax Provision (Details) Sheet http://www.itctransco.com/role/IncomeTaxesComponentsOfIncomeTaxProvisionDetails INCOME TAXES Components of Income Tax Provision (Details) Details 68 false false R69.htm 2420404 - Disclosure - INCOME TAXES Deferred Tax Assets and Liabilities (Details) Sheet http://www.itctransco.com/role/IncomeTaxesDeferredTaxAssetsAndLiabilitiesDetails INCOME TAXES Deferred Tax Assets and Liabilities (Details) Details 69 false false R70.htm 2420405 - Disclosure - INCOME TAXES Deferred Taxes Balance Sheet Classification (Details) Sheet http://www.itctransco.com/role/IncomeTaxesDeferredTaxesBalanceSheetClassificationDetails INCOME TAXES Deferred Taxes Balance Sheet Classification (Details) Details 70 false false R71.htm 2420406 - Disclosure - INCOME TAXES Additional Information (Details) Sheet http://www.itctransco.com/role/IncomeTaxesAdditionalInformationDetails INCOME TAXES Additional Information (Details) Details 71 false false R72.htm 2422402 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Plan Assets By Category (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustPlanAssetsByCategoryDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Plan Assets By Category (Details) Details 72 false false R73.htm 2422403 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Net Defined Benefit Cost Components (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustNetDefinedBenefitCostComponentsDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Net Defined Benefit Cost Components (Details) Details 73 false false R74.htm 2422404 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Defined Benefit Plans Disclosures (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustDefinedBenefitPlansDisclosuresDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Defined Benefit Plans Disclosures (Details) Details 74 false false R75.htm 2422405 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Assumptions Used (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustAssumptionsUsedDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Assumptions Used (Details) Details 75 false false R76.htm 2422406 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Projected Benefit Payments (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustProjectedBenefitPaymentsDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Projected Benefit Payments (Details) Details 76 false false R77.htm 2422407 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Assets Measured at Fair Value Subject to Three-Tier Hierarchy (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustAssetsMeasuredAtFairValueSubjectToThreeTierHierarchyDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Assets Measured at Fair Value Subject to Three-Tier Hierarchy (Details) Details 77 false false R78.htm 2422408 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustEffectOfOnePercentagePointChangeInAssumedHealthCareCostTrendRatesDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Details) Details 78 false false R79.htm 2422409 - Disclosure - RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Additional Information (Details) Sheet http://www.itctransco.com/role/RetirementBenefitsAndAssetsHeldInTrustAdditionalInformationDetails RETIREMENT BENEFITS AND ASSETS HELD IN TRUST Additional Information (Details) Details 79 false false R80.htm 2424402 - Disclosure - FAIR VALUE MEASUREMENTS Assets Measured at Fair Value Subject to Three-Tier Hierarchy (Details) Sheet http://www.itctransco.com/role/FairValueMeasurementsAssetsMeasuredAtFairValueSubjectToThreeTierHierarchyDetails FAIR VALUE MEASUREMENTS Assets Measured at Fair Value Subject to Three-Tier Hierarchy (Details) Details 80 false false R81.htm 2424403 - Disclosure - FAIR VALUE MEASUREMENTS Additional Information (Details) Sheet http://www.itctransco.com/role/FairValueMeasurementsAdditionalInformationDetails FAIR VALUE MEASUREMENTS Additional Information (Details) Details 81 false false R82.htm 2426402 - Disclosure - STOCKHOLDERS' EQUITY Changes in Accumulated Other Comprehensive Income (Details) Sheet http://www.itctransco.com/role/StockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeDetails STOCKHOLDERS' EQUITY Changes in Accumulated Other Comprehensive Income (Details) Details 82 false false R83.htm 2426403 - Disclosure - STOCKHOLDERS EQUITY Additional Information (Details) Sheet http://www.itctransco.com/role/StockholdersEquityAdditionalInformationDetails STOCKHOLDERS EQUITY Additional Information (Details) Details 83 false false R84.htm 2427402 - Disclosure - SHARE-BASED COMPENSATION Allocation of Share-based Compensation Costs (Details) Sheet http://www.itctransco.com/role/ShareBasedCompensationAllocationOfShareBasedCompensationCostsDetails SHARE-BASED COMPENSATION Allocation of Share-based Compensation Costs (Details) Details 84 false false R85.htm 2427403 - Disclosure - SHARE-BASED COMPENSATION Rollforwards (Details) Sheet http://www.itctransco.com/role/ShareBasedCompensationRollforwardsDetails SHARE-BASED COMPENSATION Rollforwards (Details) Details 85 false false R86.htm 2427404 - Disclosure - SHARE-BASED COMPENSATION Assumptions (Details) Sheet http://www.itctransco.com/role/ShareBasedCompensationAssumptionsDetails SHARE-BASED COMPENSATION Assumptions (Details) Details 86 false false R87.htm 2427405 - Disclosure - SHARE-BASED COMPENSATION Additional Information (Details) Sheet http://www.itctransco.com/role/ShareBasedCompensationAdditionalInformationDetails SHARE-BASED COMPENSATION Additional Information (Details) Details 87 false false R88.htm 2428402 - Disclosure - JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES Schedule of Jointly Owned Utility Plant (Details) Sheet http://www.itctransco.com/role/JointlyOwnedUtilityPlantCoordinatedServicesScheduleOfJointlyOwnedUtilityPlantDetails JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES Schedule of Jointly Owned Utility Plant (Details) Details 88 false false R89.htm 2428403 - Disclosure - JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES Additional Information (Details) Sheet http://www.itctransco.com/role/JointlyOwnedUtilityPlantCoordinatedServicesAdditionalInformationDetails JOINTLY OWNED UTILITY PLANT/COORDINATED SERVICES Additional Information (Details) Details 89 false false R90.htm 2429403 - Disclosure - COMMITMENTS AND CONTINGENT LIABILITIES (Details) Sheet http://www.itctransco.com/role/CommitmentsAndContingentLiabilitiesDetails COMMITMENTS AND CONTINGENT LIABILITIES (Details) Details http://www.itctransco.com/role/CommitmentsAndContingentLiabilitiesTables 90 false false R91.htm 2430401 - Disclosure - ENTERGY TRANSACTION (Details) Sheet http://www.itctransco.com/role/EntergyTransactionDetails ENTERGY TRANSACTION (Details) Details http://www.itctransco.com/role/EntergyTransaction 91 false false R92.htm 2431402 - Disclosure - SEGMENT INFORMATION (Details) Sheet http://www.itctransco.com/role/SegmentInformationDetails SEGMENT INFORMATION (Details) Details http://www.itctransco.com/role/SegmentInformationTables 92 false false R93.htm 2432402 - Disclosure - SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (Unaudited) (Details) Sheet http://www.itctransco.com/role/SupplementaryQuarterlyFinancialInformationUnauditedDetails SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (Unaudited) (Details) Details http://www.itctransco.com/role/SupplementaryQuarterlyFinancialInformationUnauditedTables 93 false false R94.htm 2434401 - Disclosure - SUBSEQUENT EVENTS (Details) Sheet http://www.itctransco.com/role/SubsequentEventsDetails SUBSEQUENT EVENTS (Details) Details http://www.itctransco.com/role/SubsequentEvents 94 false false R95.htm 2435401 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Financial Position (Parent Company Only) (Details) Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrantCondensedStatementsOfFinancialPositionParentCompanyOnlyDetails SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Financial Position (Parent Company Only) (Details) Details 95 false false R96.htm 2435402 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Operations (Parent Company Only) (Details) Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrantCondensedStatementsOfOperationsParentCompanyOnlyDetails SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Operations (Parent Company Only) (Details) Details 96 false false R97.htm 2435403 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Comprehensive Income (Parent Company) (Details) Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrantCondensedStatementsOfComprehensiveIncomeParentCompanyDetails SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Comprehensive Income (Parent Company) (Details) Details 97 false false R98.htm 2435404 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Cash Flows (Parent Company) (Details) Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrantCondensedStatementsOfCashFlowsParentCompanyDetails SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Cash Flows (Parent Company) (Details) Details 98 false false R99.htm 2435405 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT General (Details) Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrantGeneralDetails SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT General (Details) Details http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrant 99 false false R100.htm 2435406 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Debt (Details) Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrantDebtDetails SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Debt (Details) Details http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrant 100 false false R101.htm 2435407 - Disclosure - SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Related-party Transactions (Details) Sheet http://www.itctransco.com/role/ScheduleICondensedFinancialInformationOfRegistrantRelatedPartyTransactionsDetails SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Related-party Transactions (Details) Details 101 false false All Reports Book All Reports itc-20151231.xml itc-20151231.xsd itc-20151231_cal.xml itc-20151231_def.xml itc-20151231_lab.xml itc-20151231_pre.xml true true