RELATED PARTY TRANSACTIONS Schedule of Related Party Transactions (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
Dec. 31, 2025 |
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| Accounts receivable | $ 222 | $ 222 | $ 164 | ||
| Accounts payable | 215 | 215 | 141 | ||
| Accrued taxes | 50 | 50 | 81 | ||
| General and administrative | 30 | $ 37 | 125 | $ 111 | |
| Fortis and Fortis affiliates [Member] | Affiliated Entity | |||||
| Accounts receivable | 1 | 1 | 1 | ||
| General and administrative | 3 | 2 | 12 | 11 | |
| Other operating expenses (income), net | 1 | $ 1 | 3 | $ 3 | |
| ITC Investment Holdings | Affiliated Entity | Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent | |||||
| Income Taxes Receivable, Current | 3 | 3 | 2 | ||
| Accrued taxes | $ 2 | $ 2 | $ 0 | ||
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- Definition Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Carrying amount due within one year of the balance sheet date (or one operating cycle, if longer) from tax authorities as of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations. No definition available.
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- Definition Carrying value as of the balance sheet date of obligations incurred and payable for statutory income, sales, use, payroll, excise, real, property and other taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Reference 1: http://www.xbrl.org/2003/role/exampleRef
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