BENEFIT PLANS (Tables)

3 Months Ended

Mar. 31, 2025

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Pension Plans

Three Months Ended March 31, 2025	AEP		AEP Texas		APCo		I&M		OPCo		PSO		SWEPCo
	(in millions)
Service Cost	$	24.0	$	2.2	$	2.4	$	3.2	$	2.3	$	1.4	$	1.9
Interest Cost	52.8		4.5		6.2		6.2		4.9		2.7		3.2
Expected Return on Plan Assets	(70.3)		(5.6)		(9.4)		(9.7)		(7.3)		(3.9)		(3.7)
Amortization of Net Actuarial Loss	4.1		0.3		0.4		0.4		0.3		0.2		0.2
Net Periodic Benefit Cost (Credit)	$	10.6	$	1.4	$	(0.4)	$	0.1	$	0.2	$	0.4	$	1.6

Three Months Ended March 31, 2024	AEP		AEP Texas		APCo		I&M		OPCo		PSO		SWEPCo
	(in millions)
Service Cost	$	25.6	$	2.2	$	2.4	$	3.3	$	2.4	$	1.5	$	1.9
Interest Cost	51.9		4.3		6.2		6.0		4.7		2.5		3.1
Expected Return on Plan Assets	(80.2)		(6.4)		(10.7)		(10.8)		(8.2)		(4.3)		(4.4)
Amortization of Net Actuarial Loss	1.1		0.1		0.1		0.1		0.1		—		0.1
Net Periodic Benefit Cost (Credit)	$	(1.6)	$	0.2	$	(2.0)	$	(1.4)	$	(1.0)	$	(0.3)	$	0.7

OPEB

Three Months Ended March 31, 2025	AEP		AEP Texas		APCo		I&M		OPCo		PSO		SWEPCo
	(in millions)
Service Cost	$	0.8	$	0.1	$	0.1	$	0.1	$	0.1	$	—	$	0.1
Interest Cost	8.6		0.6		1.4		1.0		0.8		0.4		0.5
Expected Return on Plan Assets	(28.2)		(2.3)		(4.1)		(3.4)		(2.9)		(1.5)		(1.9)
Amortization of Prior Service Credit	(0.6)		—		(0.1)		(0.1)		(0.1)		—		—
Amortization of Net Actuarial Gain	(0.3)		—		(0.1)		—		—		—		—
Net Periodic Benefit Credit	$	(19.7)	$	(1.6)	$	(2.8)	$	(2.4)	$	(2.1)	$	(1.1)	$	(1.3)

Three Months Ended March 31, 2024	AEP		AEP Texas		APCo		I&M		OPCo		PSO		SWEPCo
	(in millions)
Service Cost	$	1.1	$	0.1	$	0.1	$	0.1	$	0.1	$	0.1	$	0.1
Interest Cost	10.5		0.8		1.7		1.2		1.1		0.5		0.7
Expected Return on Plan Assets	(27.8)		(2.3)		(4.0)		(3.4)		(3.0)		(1.4)		(1.9)
Amortization of Prior Service Credit	(3.2)		(0.3)		(0.5)		(0.4)		(0.3)		(0.2)		(0.3)
Amortization of Net Actuarial Loss	0.8		0.1		0.1		0.1		0.1		—		0.1
Net Periodic Benefit Credit	$	(18.6)	$	(1.6)	$	(2.6)	$	(2.4)	$	(2.0)	$	(1.0)	$	(1.3)