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- Definition

Short-Term Debt, Weighted Average Days to Maturity

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Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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DEBT (Details) - USD ($) $ in Millions	3 Months Ended
DEBT (Details) - USD ($) $ in Millions	Mar. 31, 2026	Apr. 01, 2026	Mar. 12, 2026	Jan. 14, 2026
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 600
Short-Term Debt, Weighted Average Interest Rate, at Point in Time	4.07%
Short-Term Debt, Weighted Average Days to Maturity	2 days
ITC Holdings Corp.
Debt Instrument [Line Items]
Commercial Paper Program, Maximum Authorized Amount Outstanding	$ 400
Commercial Paper	381
ITC Holdings Corp. \| Unsecured Debt \| Subsequent Event
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 900
ITC Holdings Corp. \| Senior Notes, due April 15, 2031 \| Unsecured Debt \| Subsequent Event
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 500
Debt Instrument, Interest Rate, Stated Percentage		4.875%
ITC Holdings Corp. \| Senior Notes, due April 15, 2036 \| Unsecured Debt \| Subsequent Event
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 400
Debt Instrument, Interest Rate, Stated Percentage		5.50%
ITC Holdings Corp. \| Notes, due June 30, 2026 \| Unsecured Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 400
Debt Instrument, Interest Rate, Stated Percentage	3.25%
ITC Midwest LLC \| First Mortgage Bonds, Series O, due March 12, 2035 \| Secured Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 175
Debt Instrument, Interest Rate, Stated Percentage			4.86%
ITCTransmission \| First Mortgage Bonds, Series M, due March 12, 2034 \| Secured Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 175
Debt Instrument, Interest Rate, Stated Percentage			4.78%
METC LLC \| Senior Secured Notes, Series A, due January 14, 2036 \| Secured Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 125
Debt Instrument, Interest Rate, Stated Percentage				5.08%
METC LLC \| Senior Secured Notes, Series B, due January 14, 2046 \| Secured Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 125
Debt Instrument, Interest Rate, Stated Percentage				5.71%