COMMITMENTS AND CONTINGENT LIABILITIES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Dec. 31, 2025	Oct. 17, 2024
Commitments and Contingent Liabilities [Line Items]
Regulatory liabilities	$ 18	$ 23
MISO Operating Subsidiaries \| Rate of Return on Equity and Capital Structure October 2024 Order
Commitments and Contingent Liabilities [Line Items]
Revised Rate Of Return On Equity			10.73%
Required customer refund paid	7
MISO Operating Subsidiaries \| Rate of Return on Equity and Capital Structure October 2024 Order \| Refund related to the October 2024 Order, Including Accrued Interest
Commitments and Contingent Liabilities [Line Items]
Regulatory liabilities	1	7
MISO Operating Subsidiaries \| Rate of Return on Equity and Capital Structure October 2024 Order \| Refund related to the October 2024 Order, Accrued Interest
Commitments and Contingent Liabilities [Line Items]
Regulatory liabilities	$ 1	$ 2
Minimum [Member] \| MISO Operating Subsidiaries \| Rate of Return on Equity and Capital Structure October 2024 Order
Commitments and Contingent Liabilities [Line Items]
Revised Rate Of Return On Equity			9.98%
Maximum [Member] \| MISO Operating Subsidiaries \| Rate of Return on Equity and Capital Structure October 2024 Order
Commitments and Contingent Liabilities [Line Items]
Revised Rate Of Return On Equity			12.58%