COMMITMENTS AND CONTINGENT LIABILITIES (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025	Oct. 17, 2024
Commitments and Contingent Liabilities [Line Items]
Regulatory liabilities	$ 19		$ 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	$ 6
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	0		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	$ 0		$ 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%