FINANCING ACTIVITIES - Schedule of Short-term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Short-Term Debt [Line Items]
Short-term – Securitized Debt of Receivables	$ 900	$ 900
Interest Rate	3.92%	4.00%
Commercial Paper	$ 651	$ 605
Total Short-term Debt	1,555	1,508
SOUTHWESTERN ELECTRIC POWER COMPANY
Short-Term Debt [Line Items]
Notes Payable	4	3
Total Short-term Debt	$ 4	$ 3
Commercial Paper
Short-Term Debt [Line Items]
Weighted-Average Interest Rate	4.08%	3.92%
Notes Payable \| SOUTHWESTERN ELECTRIC POWER COMPANY
Short-Term Debt [Line Items]
Weighted-Average Interest Rate	6.02%	6.30%

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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Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Carrying amount of liabilities associated with financial assets accounted for as secured borrowings recognized in the transferor's statement of financial position at the end of each period presented.

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