FINANCING ACTIVITIES - Schedule of Accounts Receivable and Accrued Unbilled Revenues (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
APCo
Short-Term Debt [Line Items]
Accounts receivable and accrued unbilled revenues	$ 203	$ 193
I&M
Short-Term Debt [Line Items]
Accounts receivable and accrued unbilled revenues	175	161
OPCo
Short-Term Debt [Line Items]
Accounts receivable and accrued unbilled revenues	501	471
PSO
Short-Term Debt [Line Items]
Accounts receivable and accrued unbilled revenues	140	111
SWEPCo
Short-Term Debt [Line Items]
Accounts receivable and accrued unbilled revenues	$ 169	$ 154