Fair Value, Net Asset (Liability) Fair Value, Net Asset (Liability) Maximum [Member] Maximum [Member] Interest Rate Swap with effective date of September 15, 2027 Interest Rate Swap, effective date of Q3 2027 [Member] Interest Rate Swap, effective date of Q3 2027 [Member] SHARE-BASED COMPENSATION AND EMPLOYEE SHARE PURCHASE PLAN Share-Based Payment Arrangement [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Subsequent Event Subsequent Event [Member] Document Fiscal Year Focus Document Fiscal Year Focus Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate Financial Instrument [Axis] Financial Instrument [Axis] Senior Notes, due April 15, 2031 Senior Notes, due April 15, 2031 [Member] Senior Notes, due April 15, 2031 MISO Operating Subsidiaries MISO Operating Subsidiaries [Member] MISO Operating Subsidiaries [Member] Other non-current liabilities Other Liabilities, Noncurrent Segment Reporting [Abstract] Segment Reporting [Abstract] Goodwill Goodwill Retirement Plan Type [Axis] Retirement Plan Type [Axis] Revised Rate Of Return On Equity Revised Rate Of Return On Equity Revised Rate Of Return On Equity Common stock, without par value, 235,000,000 shares authorized, 224,203,112 shares issued and outstanding Common Stock, Value, Issued Document - Document and Entity Information [Abstract] Document - Document and Entity Information [Abstract] Document - Document and Entity Information [Abstract] Accrued compensation Employee-related Liabilities, Current Subsequent Event Type [Domain] Subsequent Event Type [Domain] Pension and Other Postretirement Benefits Disclosure Retirement Benefits [Text Block] Retained Earnings [Member] Retained Earnings [Member] Accrued taxes Taxes Payable, Current Other services Other services [Member] Other services [Member] Net issuances of commercial paper Proceeds from (Repayments of) Commercial Paper Total operating expenses Operating Expenses Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding Derivative Instrument [Axis] Derivative Instrument [Axis] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Current Reporting Status Entity Current Reporting Status Net cash provided by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Senior Notes, due April 15, 2036 Senior Notes, due April 15, 2036 [Member] Senior Notes, due April 15, 2036 Interest Rate Swap Interest Rate Swap, settled March 2026 [Member] Interest Rate Swap, settled March 2026 [Member] Cash Flow Hedging [Member] Cash Flow Hedging [Member] Refund related to the October 2024 Order, Accrued Interest Refund related to the October 2024 Order, Accrued Interest [Member] Refund related to the October 2024 Order, Accrued Interest Regulatory liabilities Non-current regulatory liabilities Regulatory Liability, Noncurrent Accrued compensation Increase (Decrease) in Employee Related Liabilities Schedule of Issued Debt [Table] Schedule of Issued Debt [Table Text Block] Schedule of Issued Debt Amendment Flag Amendment Flag Current liabilities Liabilities, Current [Abstract] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Allowance for equity funds used during construction Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Operation and maintenance Utilities Operating Expense, Maintenance and Operations Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Regulated Operating Subsidiaries Regulated Operating Subsidiaries [Member] Regulated Operating Subsidiaries [Member] First Mortgage Bonds, Series O, due March 12, 2035 First Mortgage Bonds, Series O, due March 12, 2035 [Member] First Mortgage Bonds, Series O, due March 12, 2035 Share-based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] CASH FLOWS FROM FINANCING ACTIVITIES Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Transmission and other services Revenue from Contract with Customer, Excluding Assessed Tax Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Unused Capacity Line of Credit Facility, Remaining Borrowing Capacity Interest cost Defined Benefit Plan, Interest Cost Income taxes paid to state jurisdictions Income Tax Paid, State and Local, after Refund Received Financial Instruments [Domain] Financial Instruments [Domain] Liabilities, Noncurrent Liabilities, Noncurrent Related Party Transactions Disclosure Related Party Transactions Disclosure [Text Block] Other Non-cash Investing and Financing Other Non-cash Investing and Financing Other Non-cash Investing and Financing Entity Address, State or Province Entity Address, State or Province Granted Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Granted REGULATORY MATTERS Public Utilities Disclosure [Text Block] REVENUE Revenue from Contract with Customer [Text Block] Expenditures for property, plant and equipment Segment Reporting, Long-Lived Asset, Expenditure for Addition Accrued interest Increase (Decrease) in Interest Payable, Net Derivative, Notional Amount Derivative, Notional Amount Retirement Benefits [Abstract] Retirement Benefits [Abstract] Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Other Payment for (Proceeds from) Other Investing Activity Regulatory assets Non-current regulatory assets Regulatory Asset, Noncurrent Total current liabilities Liabilities, Current Regulatory Liability [Axis] Regulatory Liability [Axis] Segment Reporting [Table] Segment Reporting [Table] ITC Investment Holdings ITC Investment Holdings [Member] ITC Investment Holdings Taxes other than income taxes Taxes, Miscellaneous Schedule of Debt Instruments [Table] Schedule of Debt Instruments [Table] Schedule of Debt Instruments [Table] Statement [Table] Related Party Transaction [Table] Schedule of Derivative Instruments Schedule of Derivative Instruments [Table Text Block] Schedule of Regulatory Assets and Liabilities [Line Items] Schedule of Regulatory Assets and Liabilities [Line Items] [Line Items] for Schedule of Regulatory Assets and Liabilities [Table] ITCTransmission ITCTransmission [Member] ITCTransmission Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Entity Address, City or Town Entity Address, City or Town Supplementary Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax OPERATING INCOME Operating Income (Loss) Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Current Fiscal Year End Date Current Fiscal Year End Date Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] ACCOUNTS RECEIVABLE Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Receivables [Abstract] Receivables [Abstract] Commercial Paper Commercial Paper Segment Reporting, Descriptive Information [Abstract] Segment Reporting, Descriptive Information [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Derivative Instruments [Abstract] Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative [Line Items] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Receivable [Domain] Receivable [Domain] OTHER EXPENSES (INCOME) Nonoperating Income (Expense) [Abstract] Entity File Number Entity File Number Service cost Defined Benefit Plan, Service Cost Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX Total other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Debt maturing within one year Long-Term Debt, Current Maturities Common Stock, Shares, Issued Common Stock, Shares, Issued Subsequent Event Type [Axis] Subsequent Event Type [Axis] ITC Midwest LLC ITC Midwest LLC [Member] ITC Midwest LLC Entity Information [Line Items] Entity Information [Line Items] Additions to property, plant and equipment and other long-lived assets Capital Expenditures Incurred but Not yet Paid Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Schedule of Financial Information by Reportable Segment Segment Reporting [Table Text Block] Equity Components [Axis] Equity Components [Axis] Accounts receivable Increase (Decrease) in Accounts Receivable Related Party [Axis] Related and Nonrelated Parties [Axis] Unsecured Debt Unsecured Debt [Member] Product and Service [Domain] Product and Service [Domain] Recognition, refund and collection of revenue accruals and deferrals — including accrued interest Increase (Decrease) in Regulatory Assets and Liabilities Interest Rate Swaps Derivatives Interest Rate Derivative Assets, at Fair Value Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Repayments of revolving credit agreement Repayments of Lines of Credit Entity Interactive Data Current Entity Interactive Data Current Book value of consolidated long-term debt and debt maturing within one year, net of discount and deferred financing fees and excluding borrowings on the revolving credit agreement and commercial paper Long-Term Debt Deferred income taxes Deferred Income Tax Liabilities, Net Defined Contribution Plan, Cost Defined Contribution Plan, Cost Entity Small Business Entity Small Business Incentive Adder for Independent Transmission Ownership Incentive Adder for Independent Transmission Ownership Incentive Adder for Independent Transmission Ownership TOTAL COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent Document Period End Date Document Period End Date Changes in assets and liabilities, exclusive of changes shown separately: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Schedule of Regulatory Assets and Liabilities Schedule of Regulatory Assets and Liabilities Associated with Regulated Operating Subsidiaries' Formula Rate Revenue Accruals and Deferrals [Table Text Block] Tabular disclosure of the current and non-current regulatory assets and liabilities associated with our Regulated Operating Subsidiaries' formula rate revenue accruals and deferrals. Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Debt Instrument, Face Amount Debt Instrument, Face Amount Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] STOCKHOLDER'S EQUITY Equity [Text Block] Transmission Rate, Applicable Period Transmission Rate, Applicable Period Transmission Rate, Applicable Period Other current liabilities Other Liabilities, Current Other non-current assets Other Assets, Noncurrent Reconciliations/Eliminations Consolidation, Eliminations [Member] Document Type Document Type Revenue Accruals, Including Accrued Interest Revenue Accruals, Including Accrued Interest [Member] Revenue Accruals, Including Accrued Interest [Member] Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Aggregate fair value of PBUs or SBUs Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding SUPPLEMENTAL FINANCIAL INFORMATION Cash Flow, Supplemental Disclosures [Text Block] Net collection of 2024 revenue deferrals and accruals, including accrued interest Net Refunds (Collections) Of Revenue Deferrals And Accruals Including Interest Net Refunds (Collections) Of Revenue Deferrals and Accruals, Including Interest, During the Period Accumulated other comprehensive income Balance at the beginning of period Balance at the end of period Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] Refundable deposits from generators for transmission network upgrades Refundable Deposits from Generators for Transmission Network Upgrades, Financing Activities Refundable Deposits from Generators for Transmission Network Upgrades, Financing Activities Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Issuances of long-term debt, net Proceeds from Issuance of Long-Term Debt Accrued interest Interest Payable, Current Local Phone Number Local Phone Number Mutual fund - fixed income securities [Member] Mutual fund - fixed income securities [Member] Mutual fund - fixed income securities [Member] Other Postretirement Benefits Plan Other Postretirement Benefits Plan [Member] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Consolidation Items [Axis] Consolidation Items [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Document Fiscal Period Focus Document Fiscal Period Focus Notes, due June 30, 2026 Notes, due June 30, 2026 [Member] Notes, due June 30, 2026 [Member] INCOME BEFORE INCOME TAXES Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest TOTAL LIABILITIES Liabilities First Mortgage Bonds, Series M, due March 12, 2034 First Mortgage Bonds, Series M, due March 12, 2034 [Member] First Mortgage Bonds, Series M, due March 12, 2034 COMMITMENTS AND CONTINGENT LIABILITIES (Notes 5 and 12) Commitments and Contingencies Total operating revenues Operating revenues Revenues Depreciation and amortization Utilities Operating Expense, Depreciation and Amortization Subsidiary net earnings Income (Loss) from Equity Method Investments Expenditures for property, plant and equipment Payments to Acquire Property, Plant, and Equipment Non-current assets Other Assets [Abstract] Commitments and Contingent Liabilities [Table] Commitments and Contingent Liabilities [Table] Commitments and Contingent Liabilities [Table] Refund related to the October 2024 Order, Including Accrued Interest Refund related to the October 2024 Order, Including Accrued Interest [Member] Refund related to the October 2024 Order, Including Accrued Interest Receivable Type [Axis] Receivable Type [Axis] Restrictions on Cash and Cash Equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Counterparty Name [Axis] Counterparty Name [Axis] LIABILITIES AND STOCKHOLDER’S EQUITY Liabilities and Equity [Abstract] Assets and Liabilities at Fair Value Subject to Three-Tier Hierarchy Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Inventory Inventory, Net Award Type [Domain] Award Type [Domain] FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Fair Value, Inputs, Level 3 Fair Value, Inputs, Level 3 [Member] Mutual fund - equity securities [Member] Mutual fund - equity securities [Member] Mutual fund - equity securities [Member] Net revenue accruals, including accrued interest Net Revenue Accruals (Deferrals) For The Period Net Revenue Accruals (Deferrals) For The Period Commitment Fee Rate Line of Credit Facility, Commitment Fee Percentage Related Party Transactions [Abstract] Related Party Transactions [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Income Tax Paid, before Refund Received Income Tax Paid, before Refund Received Other Segment Items Segment Reporting, Other Segment Item, Amount Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Accrued pension and postretirement liabilities Liability, Defined Benefit Plan, Noncurrent Line of Credit Facility [Table] Line of Credit Facility [Table] Entity Tax Identification Number Entity Tax Identification Number Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instruments and Hedging Activities Disclosures [Table] Derivative instruments, net of tax Other Comprehensive Income, Other, Net of Tax Borrowings under revolving credit agreement Proceeds from Lines of Credit Legal Entity [Axis] Legal Entity [Axis] Gain (loss) on interest rate swaps relating to interest rate cash flow hedges (net of tax of $1 and $(1), respectively) Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Entities [Table] Entities [Table] Regulatory Asset [Axis] Regulatory Asset [Axis] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] REVENUE Revenue [Policy Text Block] CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period Cash, Cash Equivalents and Restricted Cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Accounts payable Increase (Decrease) in Accounts Payable Total available capacity Line of Credit Facility, Current Borrowing Capacity Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Other Receivables Other Receivables Short-Term Debt, Weighted Average Days to Maturity Short-Term Debt, Weighted Average Days to Maturity Short-Term Debt, Weighted Average Days to Maturity Revenue Deferrals, Including Accrued Interest Revenue Deferrals, Including Accrued Interest [Member] Revenue Deferrals, Including Accrued Interest [Member] Other current and non-current assets and liabilities, net Increase (Decrease) in Other Operating Assets and Liabilities, Net GENERAL Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Axis] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Long-Term Debt, Type [Domain] Long-Term Debt, Type [Domain] Schedule of Commercial Paper Schedule of Commercial Paper [Table Text Block] Schedule of Commercial Paper Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Senior Secured Notes, Series A, due January 14, 2036 Senior Secured Notes, Series A, due January 14, 2036 [Member] Senior Secured Notes, Series A, due January 14, 2036 Refundable deposits and advances for construction Contract with Customer, Liability, Current Schedule of Regulatory Liabilities [Table] Regulated Operation, Regulatory Liability [Table] Total current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] ITC Holdings Corp. ITC Holdings Corp. [Member] ITC Holdings Corp. [Member] Long-term debt Long-Term Debt, Excluding Current Maturities Award Type [Axis] Award Type [Axis] Commitments and Contingent Liabilities [Line Items] Commitments and Contingent Liabilities [Line Items] Commitments and Contingent Liabilities [Line Items] Regulated Operations [Abstract] Regulated Operations [Abstract] Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Retained earnings Retained Earnings (Accumulated Deficit) OTHER COMPREHENSIVE INCOME (LOSS) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Fair value of consolidated long-term debt and debt maturing within one year, excluding borrowings on the revolving credit agreement and commercial paper Long-Term Debt, Fair Value Product and Service [Axis] Product and Service [Axis] Net Defined Benefit Cost Components Schedule of Net Benefit Costs [Table Text Block] Restricted cash included in other non-current assets Restricted Cash, Noncurrent Scenario [Domain] Scenario [Domain] Ownership Percentage of Minority Investor Ownership Percentage of Minority Investor Ownership Percentage of Minority Investor Pension plans Pension Plan [Member] Common Stock [Member] Common Stock [Member] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Rate of Return on Equity and Capital Structure October 2024 Order Rate of Return on Equity and Capital Structure October 2024 Order [Member] Rate of Return on Equity and Capital Structure October 2024 Order SEGMENT INFORMATION Segment Reporting [Text Block] Outstanding Balance Outstanding balance under revolving credit agreement Long-Term Line of Credit Minimum [Member] Minimum [Member] Short-Term Debt, Weighted Average Interest Rate, at Point in Time Short-Term Debt, Weighted Average Interest Rate, at Point in Time Derivative Contract [Domain] Derivative Contract [Domain] ITC Great Plains LLC ITC Great Plains LLC [Member] ITC Great Plains LLC Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] TOTAL LIABILITIES AND STOCKHOLDER’S EQUITY Liabilities and Equity Regulatory Asset [Domain] Regulatory Asset [Domain] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Public Utilities, Regulatory Proceeding [Domain] Public Utilities, Regulatory Proceeding [Domain] Unbilled accounts receivable Unbilled Receivables, Current Segments [Axis] Segments [Axis] Affiliated Entity Affiliated Entity [Member] NumberOfReportableSegmentsNotDisclosedFlag NumberOfReportableSegmentsNotDisclosedFlag NumberOfReportableSegmentsNotDisclosedFlag Related Party [Domain] Related and Nonrelated Parties [Domain] Net cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Required customer refund paid Required customer refund paid Required customer refund paid Components of accounts receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Common Stock, Shares Authorized Common Stock, Shares Authorized Other expenses (income), net Other Nonoperating Income (Expense) Common stock, without par value Common Stock, No Par Value Other operating expenses (income), net Other Operating Income (Expense), Net Income Taxes Receivable, Current Income Taxes Receivable, Current CASH FLOWS FROM INVESTING ACTIVITIES Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Segment Reporting Segment Reporting [Line Items] Document Quarterly Report Document Quarterly Report General and administrative General and Administrative Expense Segments [Domain] Segments [Domain] Interest Rate Swap [Member] Interest Rate Swap [Member] Senior Secured Notes, Series B, due January 14, 2046 Senior Secured Notes, Series B, due January 14, 2046 [Member] Senior Secured Notes, Series B, due January 14, 2046 Loss before Income Taxes, Noncontrolling Interest Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest DEBT Debt Disclosure [Text Block] Scenario [Axis] Scenario [Axis] Net Regulatory Asset (Liability) Associated with Revenue Accruals and Deferrals Net Regulatory Asset (Liability) Associated with Revenue Accruals and Deferrals Net regulatory assets Net Regulatory Asset (Liability) Associated with Revenue Accruals and Deferrals Net Regulatory Asset (Liability) Associated with Revenue Accruals and Deferrals Reclassification of net gain relating to interest rate cash flow hedges from AOCI to earnings (net of tax of $— and $—, respectively) (a) Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Derivative, Average Fixed Interest Rate Derivative, Average Fixed Interest Rate Formula Rate true-up Formula Rate True-Up Revenue The true-up mechanism under our Formula Rates is considered an alternative revenue program of a rate-regulated utility given it permits our Regulated Operating Subsidiaries to adjust future rates in response to past activities or completed events in order to collect our actual revenue requirements under our Formula Rates. In accordance with our accounting policy, only the current year origination of the true-up is reported as a formula rate true-up. Equity Component [Domain] Equity Component [Domain] Interest paid (net of interest capitalized) Interest Paid, Excluding Capitalized Interest, Operating Activity Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Secured Debt Secured Debt [Member] Trade accounts receivable Trade Accounts Receivable [Member] Schedule of Settled Derivative Instruments Schedule of Settled Derivative Instruments [Table Text Block] Schedule of Settled Derivative Instruments Counterparty Name [Domain] Counterparty Name [Domain] Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Total stockholder’s equity Stockholders' Equity Attributable to Parent, balance at beginning of period Stockholders' Equity Attributable to Parent, balance at end of period Equity, Attributable to Parent Total other expenses (income) Nonoperating Income (Expense) Accrued taxes Increase (Decrease) in Accrued Taxes Payable Accounts payable Accounts Payable, Current Mutual funds Equity Securities, FV-NI, Current Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] ASSETS Assets [Abstract] Debt Instrument [Line Items] Debt Instrument [Line Items] Fortis and Fortis affiliates [Member] Fortis and Fortis affiliates [Member] Fortis and Fortis affiliates Gain on Sale of Derivatives Gain (Loss) on Sale of Derivatives Retirement Plan Type [Domain] Retirement Plan Type [Domain] Entity Filer Category Entity Filer Category Supplemental Cash Flow Elements [Abstract] Supplemental Cash Flow Elements [Abstract] Other Proceeds from (Payment for) Other Financing Activity Performance Based Units (PBUs) Performance Shares [Member] Schedule of Revolving Credit Agreements Schedule of Line of Credit Facilities [Table Text Block] Prepaid and other current assets Prepaid Expense and Other Assets, Current Deferred income tax expense Deferred Income Tax Expense (Benefit) Regulatory assets Current regulatory assets Regulatory Asset, Current Total unrecognized compensation cost Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Cash and cash equivalents Cash and Cash Equivalent METC LLC METC LLC [Member] METC LLC [Member] COMMITMENTS AND CONTINGENT LIABILITIES Commitments and Contingencies Disclosure [Text Block] Service Based Units (SBUs) Restricted Stock Units (RSUs) [Member] Depreciation and amortization expense Depreciation, Depletion and Amortization Entity Central Index Key Entity Central Index Key Schedule of Regulatory Assets and Liabilities [Table] Schedule of Regulatory Assets and Liabilities [Table] Schedule of Regulatory Assets and Liabilities [Table] Regulatory Liabilities [Line Items] Regulatory Liability [Line Items] Property, Plant, and Equipment, Accumulated Depreciation, Depletion, and Amortization Property, Plant, and Equipment, Accumulated Depreciation, Depletion, and Amortization ITC Holdings and Other Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Other Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Equity [Abstract] Equity [Abstract] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts and Financing Receivables [Table] Revenue Accruals and Deferrals Revenue Accruals and Deferrals [Abstract] Revenue Accruals and Deferrals [Abstract] Current assets Assets, Current [Abstract] Repayments of refundable deposits from generators for transmission network upgrades Repayment of refundable deposits from generators for transmission network upgrades Repayment of refundable deposits from generators for transmission network upgrades STOCKHOLDER’S EQUITY Equity, Attributable to Parent [Abstract] Document Transition Report Document Transition Report Entity Address, Address Line One Entity Address, Address Line One Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] INCOME TAX PROVISION Income Tax Expense (Benefit) OPERATING EXPENSES Operating Expenses [Abstract] Basis Point Incentive Adder for RTO Participation Basis Point Incentive Adder for RTO Participation Basis Point Incentive Adder for RTO Participation NET DECREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forecast [Member] Forecast [Member] City Area Code City Area Code Amortization of unrecognized gain Defined Benefit Plan, Amortization of Gain (Loss) RECENT ACCOUNTING PRONOUNCEMENTS Accounting Standards Update and Change in Accounting Principle [Text Block] Net Income (Loss) Attributable to Parent, Total NET INCOME Net income Net Income (Loss) Attributable to Parent Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] AOCI Attributable to Parent [Member] AOCI Attributable to Parent [Member] Balance Sheet Location [Axis] Location, Statement of Financial Position, Balance [Axis] Statement [Table] Statement [Table] Public Utilities, Approved Return on Equity, Percentage Public Utilities, Approved Return on Equity, Percentage Dividends to ITC Investment Holdings Payments of Dividends Regulatory liabilities Current regulatory liabilities Regulatory Liability, Current Interest Rate Derivative Liabilities, at Fair Value Interest Rate Derivative Liabilities, at Fair Value Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Derivative, Contract Term Derivative, Contract Term Regulatory Liability [Domain] Regulatory Liability [Domain] Total non-current assets Assets, Noncurrent Accumulated Other Comprehensive Income (Loss) [Line Items] Statement [Line Items] Net Changes in Regulatory Assets and Liabilities Schedule Of Changes In Regulatory Assets And Liabilities Formula Rate Revenue Accruals And Deferrals [Table Text Block] The changes in regulatory assets and liabilities (net) associated with our Regulated Operating Subsidiaries' formula rate revenue accruals and deferrals, including accrued interest, from the beginning of the period through the current reporting period. TOTAL ASSETS Assets Assets Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Entity [Domain] Entity [Domain] Commercial Paper Program, Maximum Authorized Amount Outstanding Commercial Paper Program, Maximum Authorized Amount Outstanding Commercial Paper Program, Maximum Authorized Amount Outstanding New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Accounting Standards Update and Change in Accounting Principle [Abstract] Share-based compensation Employee Benefits and Share-Based Compensation OPERATING REVENUES Revenues [Abstract] Revenue true-up amount reflected in customer bill, period of recognition Revenue True-up Amount Reflected In Customer Bill, Period of Recognition The time period from the time the true-up amount is calculated from revenue accruals and deferrals based on revenue requirements to the time the true-up amount is reflected in customer bills. Regulated Operating Subsidiaries Operating Segments [Member] Interest expense, net Interest Expense, Nonoperating