COMMITMENTS, GUARANTEES AND CONTINGENCIES - Contractual Commitments (Details) - USD ($) $ in Millions	Jan. 31, 2026	Dec. 31, 2025
Other Commitments [Line Items]
Less Than 1 Year		$ 1,856
2-3 Years		2,614
4-5 Years		630
After 5 Years		535
Total		5,635
APPALACHIAN POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		528
2-3 Years		879
4-5 Years		169
After 5 Years		68
Total		1,644
INDIANA MICHIGAN POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		374
2-3 Years		624
4-5 Years		349
After 5 Years		408
Total		1,755
PUBLIC SERVICE COMPANY OF OKLAHOMA
Other Commitments [Line Items]
Less Than 1 Year		73
2-3 Years		83
4-5 Years		36
After 5 Years		13
Total		205
SOUTHWESTERN ELECTRIC POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		109
2-3 Years		74
4-5 Years		0
After 5 Years		0
Total		183
Fuel Purchase Contracts
Other Commitments [Line Items]
Less Than 1 Year		1,103
2-3 Years		1,560
4-5 Years		338
After 5 Years		241
Total		3,242
Fuel Purchase Contracts | APPALACHIAN POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		489
2-3 Years		808
4-5 Years		126
After 5 Years		35
Total		1,458
Fuel Purchase Contracts | INDIANA MICHIGAN POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		261
2-3 Years		382
4-5 Years		200
After 5 Years		203
Total		1,046
Fuel Purchase Contracts | PUBLIC SERVICE COMPANY OF OKLAHOMA
Other Commitments [Line Items]
Less Than 1 Year		28
2-3 Years		12
4-5 Years		0
After 5 Years		0
Total		40
Fuel Purchase Contracts | SOUTHWESTERN ELECTRIC POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		102
2-3 Years		72
4-5 Years		0
After 5 Years		0
Total		174
Energy and Capacity Purchase Contracts
Other Commitments [Line Items]
Less Than 1 Year		153
2-3 Years		329
4-5 Years		292
After 5 Years		294
Total		1,068
Energy and Capacity Purchase Contracts | APPALACHIAN POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		39
2-3 Years		71
4-5 Years		43
After 5 Years		33
Total		186
Energy and Capacity Purchase Contracts | INDIANA MICHIGAN POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		113
2-3 Years		242
4-5 Years		149
After 5 Years		205
Total		709
Energy and Capacity Purchase Contracts | OHIO POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		31
2-3 Years		66
4-5 Years		60
After 5 Years		43
Total		200
Energy and Capacity Purchase Contracts | PUBLIC SERVICE COMPANY OF OKLAHOMA
Other Commitments [Line Items]
Less Than 1 Year		45
2-3 Years		71
4-5 Years		36
After 5 Years		13
Total		165
Energy and Capacity Purchase Contracts | SOUTHWESTERN ELECTRIC POWER COMPANY
Other Commitments [Line Items]
Less Than 1 Year		7
2-3 Years		2
4-5 Years		0
After 5 Years		0
Total		9
Construction Contract for Capital Assets
Other Commitments [Line Items]
Less Than 1 Year		600
2-3 Years		725
4-5 Years		0
After 5 Years		0
Total		$ 1,325
Solid Oxide Fuel Cells | Subsequent Event
Other Commitments [Line Items]
Total	$ 2,650