ACQUISITIONS, DISPOSITIONS AND IMPAIRMENTS - Impact of Asset Acquisitions (Details) MW in Millions, $ in Millions	1 Months Ended		12 Months Ended
	Dec. 31, 2025 USD ($) MW	Nov. 30, 2025 USD ($) MW	Dec. 31, 2025 USD ($) MW	Dec. 31, 2024 USD ($)
Asset Acquisition, Contingent Consideration [Line Items]
Property, Plant and Equipment, Net	$ 92,374		$ 92,374	$ 82,416
Operating Lease Assets	661		661	580
Asset Retirement Obligations	3,556		3,556	3,531
Regulatory Liabilities and Deferred Investment Tax Credits	8,362		8,362	8,344
Other Current Liabilities	1,898		1,898	1,490
Deferred credits and other noncurrent liabilities	905		905	801
SOUTHWESTERN ELECTRIC POWER COMPANY
Asset Acquisition, Contingent Consideration [Line Items]
Property, Plant and Equipment, Net	11,341		11,341	9,446
Operating Lease Assets	198		198	141
Asset Retirement Obligations	252		252	257
Regulatory Liabilities and Deferred Investment Tax Credits	531		531	611
Other Current Liabilities	191		191	160
Deferred credits and other noncurrent liabilities	53		53	63
APPALACHIAN POWER COMPANY
Asset Acquisition, Contingent Consideration [Line Items]
Property, Plant and Equipment, Net	14,713		14,713	13,613
Operating Lease Assets	95		95	67
Asset Retirement Obligations	707		707	767
Regulatory Liabilities and Deferred Investment Tax Credits	1,111		1,111	1,116
Other Current Liabilities	271		271	229
Deferred credits and other noncurrent liabilities	45		45	29
PUBLIC SERVICE COMPANY OF OKLAHOMA
Asset Acquisition, Contingent Consideration [Line Items]
Property, Plant and Equipment, Net	8,964		8,964	6,532
Operating Lease Assets	126		126	106
Asset Retirement Obligations	136		136	119
Regulatory Liabilities and Deferred Investment Tax Credits	717		717	690
Other Current Liabilities	104		104	78
Deferred credits and other noncurrent liabilities	33		$ 33	$ 33
PUBLIC SERVICE COMPANY OF OKLAHOMA | VIU
Asset Acquisition, Contingent Consideration [Line Items]
Net Maximum Capacity (MWs) | MW			1,381
Property, Plant and Equipment, Net	1,842		$ 1,842
Operating Lease Assets	25		25
Asset Retirement Obligations	19		19
Other Liabilities	$ 91		91
Wagon Wheel | SOUTHWESTERN ELECTRIC POWER COMPANY
Asset Acquisition, Contingent Consideration [Line Items]
Net Maximum Capacity (MWs) | MW	598
Property, Plant and Equipment, Net	$ 1,272		1,272
Operating Lease Assets	66		66
Asset Retirement Obligations	20		$ 20
Top Hat | APPALACHIAN POWER COMPANY
Asset Acquisition, Contingent Consideration [Line Items]
Net Maximum Capacity (MWs) | MW		204
Property, Plant and Equipment, Net		$ 562
Operating Lease Assets		31
Asset Retirement Obligations		$ 4
Green Country | PUBLIC SERVICE COMPANY OF OKLAHOMA
Asset Acquisition, Contingent Consideration [Line Items]
Net Maximum Capacity (MWs) | MW			904
Property, Plant and Equipment, Net	819		$ 819
Operating Lease Assets	0		0
Asset Retirement Obligations	0		0
Other Liabilities	91		91
Green Country | PUBLIC SERVICE COMPANY OF OKLAHOMA | VIU
Asset Acquisition, Contingent Consideration [Line Items]
Regulatory Liabilities and Deferred Investment Tax Credits	50		50
Other Current Liabilities	21		21
Deferred credits and other noncurrent liabilities	20		$ 20
Pixley | PUBLIC SERVICE COMPANY OF OKLAHOMA
Asset Acquisition, Contingent Consideration [Line Items]
Net Maximum Capacity (MWs) | MW			189
Property, Plant and Equipment, Net	380		$ 380
Operating Lease Assets	9		9
Asset Retirement Obligations	12		12
Other Liabilities	0		$ 0
Flat Ridge IV | PUBLIC SERVICE COMPANY OF OKLAHOMA
Asset Acquisition, Contingent Consideration [Line Items]
Net Maximum Capacity (MWs) | MW			135
Property, Plant and Equipment, Net	305		$ 305
Operating Lease Assets	7		7
Asset Retirement Obligations	3		3
Other Liabilities	0		$ 0
Flat Ridge V | PUBLIC SERVICE COMPANY OF OKLAHOMA
Asset Acquisition, Contingent Consideration [Line Items]
Net Maximum Capacity (MWs) | MW			153
Property, Plant and Equipment, Net	338		$ 338
Operating Lease Assets	9		9
Asset Retirement Obligations	4		4
Other Liabilities	$ 0		$ 0