RATE MATTERS - OPCo Rate Matters (Details) - USD ($) $ in Millions	1 Months Ended			12 Months Ended
	Jan. 31, 2026	Oct. 31, 2025	May 31, 2025	Dec. 31, 2025
OHIO POWER COMPANY | 2025 Ohio Base Rate Case
Public Utilities, General Disclosures [Line Items]
Requested annual base rate increase (decrease)			$ 97
Requested return on equity			10.90%
Requested debt capital structure			49.10%
Requested equity capital structure			50.90%
Recommended exclusion of investments from rate base		$ 59
Recommended exclusion of capitalized incentives		55
Recommended reduction in employee related expenses		23
OHIO POWER COMPANY | 2025 Ohio Base Rate Case | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Requested return on equity	9.84%
OHIO POWER COMPANY | 2025 Ohio Base Rate Case | Minimum
Public Utilities, General Disclosures [Line Items]
Requested annual base rate increase (decrease)		$ (12)
Requested return on equity		9.33%
OHIO POWER COMPANY | 2025 Ohio Base Rate Case | Maximum
Public Utilities, General Disclosures [Line Items]
Requested annual base rate increase (decrease)		$ (28)
Requested return on equity		9.84%
OHIO POWER COMPANY | Annual Rider Revenue Requirements
Public Utilities, General Disclosures [Line Items]
Requested annual base rate increase (decrease)			$ 308
PUBLIC SERVICE COMPANY OF OKLAHOMA | 2025 Ohio Base Rate Case | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Public utilities, net annual revenue increase	$ 11
Public utilities, net annual revenue settlement of amortization	$ 82
Public utilities, net annual revenue settlement of amortization period	18 months
Public utilities, net annual revenue decrease	$ 59
Settlement changes, period after approval	14 days
OVEC-Related Purchased Power | OHIO POWER COMPANY
Public Utilities, General Disclosures [Line Items]
Reduction related to deferred costs no longer recoverable				$ 24