REGULATORY MATTERS (Details)	3 Months Ended
REGULATORY MATTERS (Details)	Mar. 31, 2026	Oct. 17, 2024
Regulatory Liabilities [Line Items]
Transmission Rate, Applicable Period	1 year
Revenue true-up amount reflected in customer bill, period of recognition	2 years
MISO Operating Subsidiaries
Regulatory Liabilities [Line Items]
Incentive Adder for Independent Transmission Ownership		25
Basis Point Incentive Adder for RTO Participation		50
MISO Operating Subsidiaries \| Rate of Return on Equity and Capital Structure October 2024 Order
Regulatory Liabilities [Line Items]
Revised Rate Of Return On Equity		10.73%
ITC Great Plains LLC
Regulatory Liabilities [Line Items]
Public Utilities, Approved Return on Equity, Percentage	11.41%
Incentive Adder for Independent Transmission Ownership	25
Basis Point Incentive Adder for RTO Participation	50
Minimum [Member] \| MISO Operating Subsidiaries \| Rate of Return on Equity and Capital Structure October 2024 Order
Regulatory Liabilities [Line Items]
Revised Rate Of Return On Equity		9.98%
Minimum [Member] \| ITC Great Plains LLC
Regulatory Liabilities [Line Items]
Public Utilities, Approved Return on Equity, Percentage	10.66%