INCOME TAXES - Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Federal:
Current	$ (2.8)	$ (116.7)	$ 113.1
Deferred	(57.9)	115.9	(88.8)
Total Federal	(60.7)	(0.8)	24.3
State and Local:
Current	(5.2)	69.0	26.6
Deferred	26.7	(13.6)	(45.5)
Total State and Local	21.5	55.4	(18.9)
Income Tax Expense (Benefit)	(39.2)	54.6	5.4
AEP TEXAS INC.
Federal:
Current	22.1	19.8	29.0
Deferred	77.1	63.5	41.4
Total Federal	99.2	83.3	70.4
State and Local:
Current	2.9	2.7	2.2
Deferred	0.0	(0.1)	0.0
Total State and Local	2.9	2.6	2.2
Income Tax Expense (Benefit)	102.1	85.9	72.6
AEP TRANSMISSION COMPANY, LLC
Federal:
Current	75.1	93.9	98.0
Deferred	89.1	52.3	46.0
Total Federal	164.2	146.2	144.0
State and Local:
Current	5.6	9.1	8.8
Deferred	20.5	(8.2)	16.3
Total State and Local	26.1	0.9	25.1
Income Tax Expense (Benefit)	190.3	147.1	169.1
APPALACHIAN POWER COMPANY
Federal:
Current	79.9	62.2	(61.0)
Deferred	(17.8)	(60.5)	86.6
Total Federal	62.1	1.7	25.6
State and Local:
Current	12.6	6.3	(0.4)
Deferred	0.4	6.2	(7.0)
Total State and Local	13.0	12.5	(7.4)
Income Tax Expense (Benefit)	75.1	14.2	18.2
INDIANA MICHIGAN POWER COMPANY
Federal:
Current	16.6	93.2	43.4
Deferred	(118.8)	(56.9)	(51.3)
Total Federal	(102.2)	36.3	(7.9)
State and Local:
Current	7.0	21.1	10.9
Deferred	0.0	1.2	1.2
Total State and Local	7.0	22.3	12.1
Income Tax Expense (Benefit)	(95.2)	58.6	4.2
OHIO POWER COMPANY
Federal:
Current	41.5	46.6	(27.0)
Deferred	(2.7)	2.8	73.3
Total Federal	38.8	49.4	46.3
State and Local:
Current	3.1	(0.3)	(0.3)
Deferred	10.5	5.2	(1.8)
Total State and Local	13.6	4.9	(2.1)
Income Tax Expense (Benefit)	52.4	54.3	44.2
PUBLIC SERVICE COMPANY OF OKLAHOMA
Federal:
Current	(119.0)	(60.8)	(3.3)
Deferred	20.1	2.9	(50.5)
Total Federal	(98.9)	(57.9)	(53.8)
State and Local:
Current	(0.2)	0.3	0.0
Deferred	(0.5)	4.0	4.6
Total State and Local	(0.7)	4.3	4.6
Income Tax Expense (Benefit)	(99.6)	(53.6)	(49.2)
SOUTHWESTERN ELECTRIC POWER COMPANY
Federal:
Current	(111.4)	(88.1)	(32.3)
Deferred	(86.1)	59.9	13.4
Total Federal	(197.5)	(28.2)	(18.9)
State and Local:
Current	1.8	1.0	(1.8)
Deferred	11.7	(6.1)	(4.5)
Total State and Local	13.5	(5.1)	(6.3)
Income Tax Expense (Benefit)	$ (184.0)	$ (33.3)	$ (25.2)