EFFECTS OF REGULATION - Regulatory Assets - OPCo (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 4,804	$ 5,129
Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	3,497	3,818
Earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	1,341	1,711
Earns/earning a return | Approved for recovery | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 100	107
Remaining Recovery Period	6 years
Earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 199	204
Does not earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	2,156	2,107
Does not earns/earning a return | Approved for recovery | Pension and OPEB Funded Status
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 796	974
Remaining Recovery Period	12 years
Does not earns/earning a return | Approved for recovery | Ohio Enhanced Service Reliability Plan
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 58	26
Remaining Recovery Period	2 years
Does not earns/earning a return | Approved for recovery | Smart Grid Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 44	34
Remaining Recovery Period	2 years
Does not earns/earning a return | Approved for recovery | Unrealized Loss on Forward Commitments
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 69	53
Remaining Recovery Period	7 years
Does not earns/earning a return | Approved for recovery | Bad Debt Rider
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 35	22
Remaining Recovery Period	2 years
Does not earns/earning a return | Approved for recovery | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 158	67
Remaining Recovery Period	6 years
Does not earns/earning a return | Approved for recovery | OVEC Purchased Power
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 0	52
Does not earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	222	229
OHIO POWER COMPANY
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	326	379
OHIO POWER COMPANY | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	326	379
OHIO POWER COMPANY | Earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	14	26
OHIO POWER COMPANY | Earns/earning a return | Approved for recovery | Ohio Basic Transmission Cost Rider
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 12	26
Remaining Recovery Period	2 years
OHIO POWER COMPANY | Earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 2	0
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	312	353
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Ohio Basic Transmission Cost Rider
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 14	0
Remaining Recovery Period	2 years
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Pension and OPEB Funded Status
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 111	134
Remaining Recovery Period	12 years
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Ohio Enhanced Service Reliability Plan
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 58	26
Remaining Recovery Period	2 years
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Smart Grid Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 44	34
Remaining Recovery Period	2 years
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Unrealized Loss on Forward Commitments
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 33	48
Remaining Recovery Period	7 years
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Bad Debt Rider
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 27	14
Remaining Recovery Period	2 years
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 18	29
Remaining Recovery Period	2 years
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | OVEC Purchased Power
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 0	52
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Ohio Distribution Investment Rider
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 0	11
Remaining Recovery Period
OHIO POWER COMPANY | Does not earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 7	$ 5