COMMITMENTS, GUARANTEES AND CONTINGENCIES - Narrative (Details)	1 Months Ended	3 Months Ended
	Nov. 30, 2025 a	Jun. 30, 2024 USD ($)	Apr. 30, 2026 USD ($)	Mar. 31, 2026 USD ($) unit a uncommittedFacility	Jan. 31, 2026 USD ($)
Other Commitments [Line Items]
Number of uncommitted facilities | uncommittedFacility				6
Area of land closed, noncompliant with CCR rule | a				300
Cook Plant | INDIANA MICHIGAN POWER COMPANY
Other Commitments [Line Items]
Nuclear contingencies, number of units | unit				2
CCR Rule Revision
Other Commitments [Line Items]
Liabilities Incurred		$ 674,000,000
Extended compliance deadline applicable period	3 years
Closure deadlines for unlined surface impoundments, minimum (in acres) | a	40
CCR Rule Revision | APPALACHIAN POWER COMPANY
Other Commitments [Line Items]
Asset retirement obligation, approved recovery amount					$ 80,000,000
Line of Credit | Revolving Credit Facility | Revolving Credit Facility, Due March 2029
Other Commitments [Line Items]
Line of credit facility, borrowing capacity				$ 5,000,000,000
Line of Credit | Revolving Credit Facility | Revolving Credit Facility, Due April 2031 | Subsequent Event
Other Commitments [Line Items]
Line of credit facility, borrowing capacity			$ 6,500,000,000
Line of Credit | Revolving Credit Facility | Revolving Credit Facility, Due March 2027
Other Commitments [Line Items]
Line of credit facility, borrowing capacity				1,000,000,000
Line of Credit | Revolving Credit Facility | Revolving Credit Facility, Due April 2029 | Subsequent Event
Other Commitments [Line Items]
Line of credit facility, borrowing capacity			$ 1,500,000,000
Line of Credit | Letter of Credit
Other Commitments [Line Items]
Debt instrument, face amount				450,000,000
Letter of Credit | Revolving Credit Facility
Other Commitments [Line Items]
Letters of credit outstanding, amount				0
Letter of Credit | Revolving Credit Facility | Subsidiaries
Other Commitments [Line Items]
Line of credit facility, borrowing capacity				$ 1,200,000,000