BENEFIT PLANS - Schedule of Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 100.6	$ 94.3	$ 123.1
Interest Cost	207.4	219.2	148.2
Expected Return on Plan Assets	(319.8)	(339.2)	(253.4)
Amortization of Net Actuarial Loss	4.5	1.4	63.0
Settlements	93.4
Net Periodic Benefit Cost (Credit)	86.1	(24.3)	80.9
Capitalized Portion	(46.6)	(43.6)	(53.8)
Net Periodic Benefit Cost (Credit) Recognized in Expense	39.5	(67.9)	27.1
Pension Plans | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Service Cost	8.9	8.2	11.1
Interest Cost	17.3	18.3	12.1
Expected Return on Plan Assets	(25.7)	(28.1)	(21.0)
Amortization of Net Actuarial Loss	0.3	0.1	5.2
Settlements	9.8
Net Periodic Benefit Cost (Credit)	10.6	(1.5)	7.4
Capitalized Portion	(5.3)	(4.7)	(6.2)
Net Periodic Benefit Cost (Credit) Recognized in Expense	5.3	(6.2)	1.2
Pension Plans | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	9.5	9.1	11.4
Interest Cost	24.7	26.4	17.5
Expected Return on Plan Assets	(42.6)	(44.6)	(32.3)
Amortization of Net Actuarial Loss	0.4	0.0	7.4
Settlements	11.8
Net Periodic Benefit Cost (Credit)	3.8	(9.1)	4.0
Capitalized Portion	(4.4)	(4.2)	(5.0)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(0.6)	(13.3)	(1.0)
Pension Plans | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	13.0	11.9	16.2
Interest Cost	23.9	24.9	17.0
Expected Return on Plan Assets	(42.9)	(44.2)	(32.4)
Amortization of Net Actuarial Loss	0.4	0.1	7.1
Settlements	9.3
Net Periodic Benefit Cost (Credit)	3.7	(7.3)	7.9
Capitalized Portion	(3.9)	(3.6)	(4.6)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(0.2)	(10.9)	3.3
Pension Plans | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	9.2	8.4	11.2
Interest Cost	18.8	19.8	13.3
Expected Return on Plan Assets	(32.6)	(34.0)	(24.8)
Amortization of Net Actuarial Loss	0.3	0.0	5.5
Settlements	6.5
Net Periodic Benefit Cost (Credit)	2.2	(5.8)	5.2
Capitalized Portion	(5.5)	(4.7)	(6.1)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(3.3)	(10.5)	(0.9)
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Service Cost	5.9	5.5	7.4
Interest Cost	10.1	10.7	7.0
Expected Return on Plan Assets	(17.3)	(18.3)	(13.4)
Amortization of Net Actuarial Loss	0.2	0.0	2.9
Settlements	5.2
Net Periodic Benefit Cost (Credit)	4.1	(2.1)	3.9
Capitalized Portion	(2.8)	(2.5)	(3.2)
Net Periodic Benefit Cost (Credit) Recognized in Expense	1.3	(4.6)	0.7
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	7.8	7.7	10.6
Interest Cost	12.5	13.9	9.1
Expected Return on Plan Assets	(17.4)	(19.4)	(14.6)
Amortization of Net Actuarial Loss	0.1	0.1	3.8
Settlements	9.3
Net Periodic Benefit Cost (Credit)	12.3	2.3	8.9
Capitalized Portion	(3.1)	(3.0)	(4.0)
Net Periodic Benefit Cost (Credit) Recognized in Expense	9.2	(0.7)	4.9
OPEB
Defined Benefit Plan Disclosure [Line Items]
Service Cost	4.5	4.6	7.4
Interest Cost	42.0	46.2	29.2
Expected Return on Plan Assets	(111.3)	(109.6)	(110.0)
Amortization of Prior Service Credit	(12.7)	(63.1)	(71.4)
Amortization of Net Actuarial Loss	3.0	14.8
Special/Contractual Termination Benefits	3.5
Net Periodic Benefit Cost (Credit)	(71.0)	(107.1)	(144.8)
Capitalized Portion	(2.1)	(2.1)	(3.2)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(73.1)	(109.2)	(148.0)
OPEB | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.3	0.3	0.5
Interest Cost	3.3	3.6	2.2
Expected Return on Plan Assets	(9.1)	(9.0)	(9.1)
Amortization of Prior Service Credit	(1.0)	(5.3)	(6.1)
Amortization of Net Actuarial Loss	0.2	1.2
Special/Contractual Termination Benefits	0.3
Net Periodic Benefit Cost (Credit)	(6.0)	(9.2)	(12.5)
Capitalized Portion	(0.2)	(0.2)	(0.3)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(6.2)	(9.4)	(12.8)
OPEB | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.5	0.5	0.8
Interest Cost	6.6	7.4	4.7
Expected Return on Plan Assets	(16.3)	(16.1)	(16.3)
Amortization of Prior Service Credit	(1.9)	(9.2)	(10.4)
Amortization of Net Actuarial Loss	0.4	2.3
Special/Contractual Termination Benefits	0.6
Net Periodic Benefit Cost (Credit)	(10.1)	(15.1)	(21.2)
Capitalized Portion	(0.2)	(0.2)	(0.4)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(10.3)	(15.3)	(21.6)
OPEB | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.6	0.6	0.9
Interest Cost	4.8	5.4	3.4
Expected Return on Plan Assets	(13.5)	(13.5)	(13.7)
Amortization of Prior Service Credit	(1.7)	(8.7)	(9.7)
Amortization of Net Actuarial Loss	0.5	1.9
Special/Contractual Termination Benefits	0.3
Net Periodic Benefit Cost (Credit)	(9.0)	(14.3)	(19.1)
Capitalized Portion	(0.2)	(0.2)	(0.3)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(9.2)	(14.5)	(19.4)
OPEB | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.4	0.4	0.6
Interest Cost	4.2	4.7	3.0
Expected Return on Plan Assets	(11.8)	(11.8)	(12.0)
Amortization of Prior Service Credit	(1.3)	(6.3)	(7.1)
Amortization of Net Actuarial Loss	0.4	1.6
Special/Contractual Termination Benefits	0.2
Net Periodic Benefit Cost (Credit)	(7.9)	(11.4)	(15.5)
Capitalized Portion	(0.2)	(0.2)	(0.3)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(8.1)	(11.6)	(15.8)
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.3	0.3	0.4
Interest Cost	2.1	2.4	1.5
Expected Return on Plan Assets	(6.0)	(5.9)	(6.1)
Amortization of Prior Service Credit	(0.7)	(4.0)	(4.4)
Amortization of Net Actuarial Loss	0.2	0.8
Special/Contractual Termination Benefits	0.2
Net Periodic Benefit Cost (Credit)	(3.9)	(6.4)	(8.6)
Capitalized Portion	(0.1)	(0.1)	(0.2)
Net Periodic Benefit Cost (Credit) Recognized in Expense	(4.0)	(6.5)	(8.8)
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.4	0.4	0.6
Interest Cost	2.7	2.9	1.8
Expected Return on Plan Assets	(7.5)	(7.2)	(7.3)
Amortization of Prior Service Credit	(1.1)	(4.9)	(5.3)
Amortization of Net Actuarial Loss	0.3	1.0
Special/Contractual Termination Benefits	0.3
Net Periodic Benefit Cost (Credit)	(4.9)	(7.8)	(10.2)
Capitalized Portion	(0.2)	(0.2)	(0.2)
Net Periodic Benefit Cost (Credit) Recognized in Expense	$ (5.1)	$ (8.0)	$ (10.4)