Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2024		Jun. 30, 2023	Jun. 30, 2024		Jun. 30, 2023
Pension Plans [Member]
Components of Net Periodic Benefit Cost
Service Cost	$ 25.6		$ 23.6	$ 51.2		$ 47.2
Interest Cost	51.9		54.8	103.8		109.6
Expected Return on Plan Assets	(80.2)		(84.8)	(160.4)		(169.6)
Amortization of Net Actuarial Loss	1.1		0.4	2.2		0.7
Net Periodic Benefit Cost (Credit)	(1.6)	[1]	(6.0)	(3.2)	[1]	(12.1)
Pension Plans [Member] | AEP Texas Inc. [Member]
Components of Net Periodic Benefit Cost
Service Cost	2.2		2.1	4.4		4.1
Interest Cost	4.4		4.6	8.7		9.2
Expected Return on Plan Assets	(6.6)		(7.0)	(13.0)		(14.0)
Amortization of Net Actuarial Loss	0.1		0.0	0.2		0.0
Net Periodic Benefit Cost (Credit)	0.1		(0.3)	0.3		(0.7)
Pension Plans [Member] | Appalachian Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	2.5		2.2	4.9		4.5
Interest Cost	6.2		6.6	12.4		13.2
Expected Return on Plan Assets	(10.7)		(11.1)	(21.4)		(22.3)
Amortization of Net Actuarial Loss	0.1		0.0	0.2		0.0
Net Periodic Benefit Cost (Credit)	(1.9)		(2.3)	(3.9)		(4.6)
Pension Plans [Member] | Indiana Michigan Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	3.3		3.0	6.6		6.0
Interest Cost	5.9		6.2	11.9		12.4
Expected Return on Plan Assets	(10.6)		(11.1)	(21.4)		(22.1)
Amortization of Net Actuarial Loss	0.1		0.0	0.2		0.0
Net Periodic Benefit Cost (Credit)	(1.3)		(1.9)	(2.7)		(3.7)
Pension Plans [Member] | Ohio Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	2.3		2.1	4.7		4.2
Interest Cost	4.7		5.0	9.4		9.9
Expected Return on Plan Assets	(8.1)		(8.5)	(16.3)		(17.0)
Amortization of Net Actuarial Loss	0.0		0.0	0.1		0.0
Net Periodic Benefit Cost (Credit)	(1.1)		(1.4)	(2.1)		(2.9)
Pension Plans [Member] | Public Service Co Of Oklahoma [Member]
Components of Net Periodic Benefit Cost
Service Cost	1.6		1.4	3.1		2.8
Interest Cost	2.5		2.7	5.0		5.4
Expected Return on Plan Assets	(4.4)		(4.6)	(8.7)		(9.2)
Amortization of Net Actuarial Loss	0.1		0.0	0.1		0.0
Net Periodic Benefit Cost (Credit)	(0.2)		(0.5)	(0.5)		(1.0)
Pension Plans [Member] | Southwestern Electric Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	2.1		1.9	4.0		3.8
Interest Cost	3.1		3.5	6.2		7.0
Expected Return on Plan Assets	(4.4)		(4.9)	(8.8)		(9.7)
Amortization of Net Actuarial Loss	0.0		0.0	0.1		0.0
Net Periodic Benefit Cost (Credit)	0.8		0.5	1.5		1.1
Other Postretirement Benefit Plans [Member]
Components of Net Periodic Benefit Cost
Service Cost	1.1		1.2	2.2		2.3
Interest Cost	10.6		11.5	21.1		23.1
Expected Return on Plan Assets	(27.9)		(27.4)	(55.7)		(54.8)
Amortization of Prior Service Cost (Credit)	(3.2)		(15.7)	(6.4)		(31.5)
Amortization of Net Actuarial Loss	0.7		3.7	1.5		7.4
Net Periodic Benefit Cost (Credit)	(18.7)	[2]	(26.7)	(37.3)	[2]	(53.5)
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member]
Components of Net Periodic Benefit Cost
Service Cost	0.1		0.1	0.2		0.2
Interest Cost	0.8		0.9	1.6		1.8
Expected Return on Plan Assets	(2.2)		(2.2)	(4.5)		(4.5)
Amortization of Prior Service Cost (Credit)	(0.2)		(1.4)	(0.5)		(2.7)
Amortization of Net Actuarial Loss	0.0		0.3	0.1		0.6
Net Periodic Benefit Cost (Credit)	(1.5)	[2]	(2.3)	(3.1)	[2]	(4.6)
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	0.1		0.2	0.2		0.3
Interest Cost	1.6		1.9	3.3		3.7
Expected Return on Plan Assets	(4.1)		(4.0)	(8.1)		(8.0)
Amortization of Prior Service Cost (Credit)	(0.4)		(2.3)	(0.9)		(4.6)
Amortization of Net Actuarial Loss	0.1		0.5	0.2		1.1
Net Periodic Benefit Cost (Credit)	(2.7)	[2]	(3.7)	(5.3)	[2]	(7.5)
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	0.2		0.2	0.3		0.4
Interest Cost	1.2		1.4	2.4		2.7
Expected Return on Plan Assets	(3.3)		(3.4)	(6.7)		(6.8)
Amortization of Prior Service Cost (Credit)	(0.5)		(2.1)	(0.9)		(4.3)
Amortization of Net Actuarial Loss	0.1		0.4	0.2		0.9
Net Periodic Benefit Cost (Credit)	(2.3)	[2]	(3.5)	(4.7)	[2]	(7.1)
Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	0.1		0.1	0.2		0.2
Interest Cost	1.0		1.1	2.1		2.3
Expected Return on Plan Assets	(2.9)		(3.0)	(5.9)		(5.9)
Amortization of Prior Service Cost (Credit)	(0.3)		(1.5)	(0.6)		(3.1)
Amortization of Net Actuarial Loss	0.1		0.4	0.2		0.8
Net Periodic Benefit Cost (Credit)	(2.0)	[2]	(2.9)	(4.0)	[2]	(5.7)
Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member]
Components of Net Periodic Benefit Cost
Service Cost	0.0		0.0	0.1		0.1
Interest Cost	0.6		0.6	1.1		1.2
Expected Return on Plan Assets	(1.6)		(1.4)	(3.0)		(2.9)
Amortization of Prior Service Cost (Credit)	(0.2)		(1.0)	(0.4)		(2.0)
Amortization of Net Actuarial Loss	0.1		0.2	0.1		0.4
Net Periodic Benefit Cost (Credit)	(1.1)	[2]	(1.6)	(2.1)	[2]	(3.2)
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	0.1		0.1	0.2		0.2
Interest Cost	0.6		0.7	1.3		1.4
Expected Return on Plan Assets	(1.8)		(1.8)	(3.7)		(3.6)
Amortization of Prior Service Cost (Credit)	(0.2)		(1.2)	(0.5)		(2.4)
Amortization of Net Actuarial Loss	0.0		0.3	0.1		0.5
Net Periodic Benefit Cost (Credit)	$ (1.3)	[2]	$ (1.9)	$ (2.6)	[2]	$ (3.9)

[1] Excludes an immaterial one-time settlement cost to a non-qualified pension plan in the second quarter of 2024 for AEP.

[2] Excludes an immaterial one-time cost related to special termination benefits resulting from the voluntary severance program announced in the second quarter of 2024. See Note 13 - Voluntary Severance Program for additional information.