Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended						9 Months Ended
		Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		$ 551.4		$ 184.8	$ 97.0		$ (85.1)	$ 184.8	$ (85.1)
Change in Fair Value Recognized in AOCI		101.7			225.7			646.0	552.1
Commodity
Generation & Marketing Revenues		5,526.1			4,623.0			14,758.4	12,730.6
Interest Rate
Interest Expense		360.7			303.7			1,001.7	895.5
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(225.5)			(60.7)			(439.1)	(243.4)
Income Tax (Expense) Benefit		(16.1)			69.8			90.7	185.5
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(178.2)			(48.0)			(346.9)	(192.3)
Net Current Period Other Comprehensive Income (Loss)		(76.5)	$ 120.8	245.8	177.7	$ 127.8	54.3	290.1	359.8
Ending Balance in AOCI		474.9	551.4		274.7	97.0		474.9	274.7
Cash Flow Hedges [Member] | Interest Rate [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		(10.8)		(21.3)	(32.2)		(47.5)	(21.3)	(47.5)
Change in Fair Value Recognized in AOCI	[1]	7.4			4.9			16.2	17.6
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.9			1.5			3.1	4.8
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.8			1.2			2.5	3.8
Net Current Period Other Comprehensive Income (Loss)		8.2			6.1			18.7	21.4
Ending Balance in AOCI		(2.6)	(10.8)		(26.1)	(32.2)		(2.6)	(26.1)
Cash Flow Hedges [Member] | Commodity [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		533.6		163.7	110.3		(60.6)	163.7	(60.6)
Change in Fair Value Recognized in AOCI		94.3			220.8			629.8	534.5
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(222.4)			(59.7)			(432.1)	(240.5)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(175.8)			(47.2)			(341.4)	(190.0)
Net Current Period Other Comprehensive Income (Loss)		(81.5)			173.6			288.4	344.5
Ending Balance in AOCI		452.1	533.6		283.9	110.3		452.1	283.9
Pension and OPEB [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		28.6		42.4	18.9		23.0	42.4	23.0
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(4.0)			(2.5)			(10.1)	(7.7)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(3.2)			(2.0)			(8.0)	(6.1)
Net Current Period Other Comprehensive Income (Loss)		(3.2)			(2.0)			(17.0)	(6.1)
Ending Balance in AOCI		25.4	28.6		16.9	18.9		25.4	16.9
Accumulated Other Comprehensive Income [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Net Current Period Other Comprehensive Income (Loss)		(76.5)	120.8	245.8	177.7	127.8	54.3
Generation and Marketing [Member]
Commodity
Generation & Marketing Revenues		733.1			617.4			1,997.0	1,641.6
Reclassifications To Accumulated Other Comprehensive Income [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Income Tax (Expense) Benefit								(2.4)
Reclassifications to AOCI, Current Period, before Tax, Attributable to Parent								(11.4)
Reclassifications to AOCI, Current Period, Net of Tax, Attributable to Parent								(9.0)
Reclassifications To Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Income Tax (Expense) Benefit								0.0
Reclassifications to AOCI, Current Period, before Tax, Attributable to Parent								0.0
Reclassifications to AOCI, Current Period, Net of Tax, Attributable to Parent								0.0
Reclassifications To Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Commodity [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Income Tax (Expense) Benefit								0.0
Reclassifications to AOCI, Current Period, before Tax, Attributable to Parent								0.0
Reclassifications to AOCI, Current Period, Net of Tax, Attributable to Parent								0.0
Reclassifications To Accumulated Other Comprehensive Income [Member] | Pension and OPEB [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Income Tax (Expense) Benefit								(2.4)
Reclassifications To Accumulated Other Comprehensive Income [Member] | Pension and OPEB [Member] | Pension Costs
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassifications to AOCI, Current Period, before Tax, Attributable to Parent								(11.4)
Reclassifications to AOCI, Current Period, Net of Tax, Attributable to Parent								(9.0)
Reclassifications from Accumulated Other Comprehensive Income [Member]
Interest Rate
Interest Expense	[2]	0.9			1.5			3.1	4.8
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(6.2)			(4.8)			(16.5)	(14.5)
Amortization of Actuarial (Gains) Losses		2.2			2.3			6.4	6.8
Income Tax (Expense) Benefit		(47.3)			(12.7)			(92.2)	(51.1)
Reclassifications from Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Interest Rate
Interest Expense	[2]	0.9			1.5			3.1	4.8
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		0.0			0.0			0.0	0.0
Amortization of Actuarial (Gains) Losses		0.0			0.0			0.0	0.0
Income Tax (Expense) Benefit		0.1			0.3			0.6	1.0
Reclassifications from Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Commodity [Member]
Interest Rate
Interest Expense	[2]	0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		0.0			0.0			0.0	0.0
Amortization of Actuarial (Gains) Losses		0.0			0.0			0.0	0.0
Income Tax (Expense) Benefit		(46.6)			(12.5)			(90.7)	(50.5)
Reclassifications from Accumulated Other Comprehensive Income [Member] | Pension and OPEB [Member]
Interest Rate
Interest Expense	[2]	0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(6.2)			(4.8)			(16.5)	(14.5)
Amortization of Actuarial (Gains) Losses		2.2			2.3			6.4	6.8
Income Tax (Expense) Benefit		(0.8)			(0.5)			(2.1)	(1.6)
Reclassifications from Accumulated Other Comprehensive Income [Member] | Generation and Marketing [Member]
Commodity
Generation & Marketing Revenues	[2]	0.2						0.2	0.7
Reclassifications from Accumulated Other Comprehensive Income [Member] | Generation and Marketing [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Commodity
Generation & Marketing Revenues	[2]	0.0						0.0	0.0
Reclassifications from Accumulated Other Comprehensive Income [Member] | Generation and Marketing [Member] | Cash Flow Hedges [Member] | Commodity [Member]
Commodity
Generation & Marketing Revenues	[2]	0.2						0.2	0.7
Reclassifications from Accumulated Other Comprehensive Income [Member] | Generation and Marketing [Member] | Pension and OPEB [Member]
Commodity
Generation & Marketing Revenues	[2]	0.0						0.0	0.0
Reclassifications from Accumulated Other Comprehensive Income [Member] | Purchased Electricity for Resale [Member]
Commodity
Purchased Electricity for Resale	[2]	(222.6)			(59.7)			(432.3)	(241.2)
Reclassifications from Accumulated Other Comprehensive Income [Member] | Purchased Electricity for Resale [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Commodity
Purchased Electricity for Resale	[2]	0.0			0.0			0.0	0.0
Reclassifications from Accumulated Other Comprehensive Income [Member] | Purchased Electricity for Resale [Member] | Cash Flow Hedges [Member] | Commodity [Member]
Commodity
Purchased Electricity for Resale	[2]	(222.6)			(59.7)			(432.3)	(241.2)
Reclassifications from Accumulated Other Comprehensive Income [Member] | Purchased Electricity for Resale [Member] | Pension and OPEB [Member]
Commodity
Purchased Electricity for Resale	[2]	0.0			0.0			0.0	0.0
Apple Blossom and Black Oak [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Change in Fair Value Recognized in AOCI		(4.0)			(1.0)			(9.0)	(5.0)
AEP Texas Inc. [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		(6.0)		(6.5)	(8.3)		(8.9)	(6.5)	(8.9)
Change in Fair Value Recognized in AOCI		0.1			0.0			0.0	0.0
Interest Rate
Interest Expense		55.4			44.2			153.2	132.5
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.3			0.4			1.0	1.1
Income Tax (Expense) Benefit		20.9			14.6			56.2	31.6
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.2			0.3			0.8	0.9
Net Current Period Other Comprehensive Income (Loss)		0.3	0.2	0.3	0.3	0.3	0.3	0.8	0.9
Ending Balance in AOCI		(5.7)	(6.0)		(8.0)	(8.3)		(5.7)	(8.0)
AEP Texas Inc. [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		(0.8)		(1.3)	(1.8)		(2.3)	(1.3)	(2.3)
Change in Fair Value Recognized in AOCI		0.1			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.3			0.4			1.0	1.0
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.2			0.3			0.8	0.8
Net Current Period Other Comprehensive Income (Loss)		0.3			0.3			0.8	0.8
Ending Balance in AOCI		(0.5)	(0.8)		(1.5)	(1.8)		(0.5)	(1.5)
AEP Texas Inc. [Member] | Pension and OPEB [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		(5.2)		(5.2)	(6.5)		(6.6)	(5.2)	(6.6)
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.0			0.0			0.0	0.1
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.0			0.0			0.0	0.1
Net Current Period Other Comprehensive Income (Loss)		0.0			0.0			0.0	0.1
Ending Balance in AOCI		(5.2)	(5.2)		(6.5)	(6.5)		(5.2)	(6.5)
AEP Texas Inc. [Member] | Accumulated Other Comprehensive Income [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Net Current Period Other Comprehensive Income (Loss)		0.3	0.2	0.3	0.3	0.3	0.3
AEP Texas Inc. [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member]
Interest Rate
Interest Expense	[2]	0.3			0.4			1.0	1.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(0.1)			(0.1)			(0.1)	(0.1)
Amortization of Actuarial (Gains) Losses		0.1			0.1			0.1	0.2
Income Tax (Expense) Benefit		0.1			0.1			0.2	0.2
AEP Texas Inc. [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Interest Rate
Interest Expense	[2]	0.3			0.4			1.0	1.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		0.0			0.0			0.0	0.0
Amortization of Actuarial (Gains) Losses		0.0			0.0			0.0	0.0
Income Tax (Expense) Benefit		0.1			0.1			0.2	0.2
AEP Texas Inc. [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Pension and OPEB [Member]
Interest Rate
Interest Expense	[2]	0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(0.1)			(0.1)			(0.1)	(0.1)
Amortization of Actuarial (Gains) Losses		0.1			0.1			0.1	0.2
Income Tax (Expense) Benefit		0.0			0.0			0.0	0.0
Appalachian Power Co [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		21.9		24.4	13.9		7.2	24.4	7.2
Change in Fair Value Recognized in AOCI		0.0			0.2			0.0	9.3
Interest Rate
Interest Expense		61.7			52.8			171.1	160.6
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(1.7)			(1.8)			(4.9)	(4.9)
Income Tax (Expense) Benefit		5.0			3.6			24.5	19.3
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(1.3)			(1.5)			(3.8)	(3.9)
Net Current Period Other Comprehensive Income (Loss)		(1.3)	(1.2)	(1.3)	(1.3)	(1.2)	7.9	(3.8)	5.4
Ending Balance in AOCI		20.6	21.9		12.6	13.9		20.6	12.6
Appalachian Power Co [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		7.1		7.5	8.0		(0.8)	7.5	(0.8)
Change in Fair Value Recognized in AOCI		0.0			0.2			0.0	9.3
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(0.3)			(0.6)			(0.8)	(1.0)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(0.2)			(0.5)			(0.6)	(0.8)
Net Current Period Other Comprehensive Income (Loss)		(0.2)			(0.3)			(0.6)	8.5
Ending Balance in AOCI		6.9	7.1		7.7	8.0		6.9	7.7
Appalachian Power Co [Member] | Pension and OPEB [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		14.8		16.9	5.9		8.0	16.9	8.0
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(1.4)			(1.2)			(4.1)	(3.9)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(1.1)			(1.0)			(3.2)	(3.1)
Net Current Period Other Comprehensive Income (Loss)		(1.1)			(1.0)			(3.2)	(3.1)
Ending Balance in AOCI		13.7	14.8		4.9	5.9		13.7	4.9
Appalachian Power Co [Member] | Accumulated Other Comprehensive Income [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Net Current Period Other Comprehensive Income (Loss)		(1.3)	(1.2)	(1.3)	(1.3)	(1.2)	7.9
Appalachian Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member]
Interest Rate
Interest Expense	[2]	(0.3)			(0.6)			(0.8)	(1.0)
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(1.4)			(1.2)			(4.1)	(3.9)
Income Tax (Expense) Benefit		(0.4)			(0.3)			(1.1)	(1.0)
Appalachian Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Interest Rate
Interest Expense	[2]	(0.3)			(0.6)			(0.8)	(1.0)
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		0.0			0.0			0.0	0.0
Income Tax (Expense) Benefit		(0.1)			(0.1)			(0.2)	(0.2)
Appalachian Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Pension and OPEB [Member]
Interest Rate
Interest Expense	[2]	0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(1.4)			(1.2)			(4.1)	(3.9)
Income Tax (Expense) Benefit		(0.3)			(0.2)			(0.9)	(0.8)
Indiana Michigan Power Co [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		(0.7)		(1.3)	(6.2)		(7.0)	(1.3)	(7.0)
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Interest Rate
Interest Expense		31.2			30.2			92.5	86.6
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.3			0.5			1.1	1.5
Income Tax (Expense) Benefit		8.0			(1.8)			7.7	(8.3)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.3			0.4			0.9	1.2
Net Current Period Other Comprehensive Income (Loss)		0.3	0.3	0.3	0.4	0.3	0.5	0.9	1.2
Ending Balance in AOCI		(0.4)	(0.7)		(5.8)	(6.2)		(0.4)	(5.8)
Indiana Michigan Power Co [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		(5.9)		(6.7)	(7.4)		(8.3)	(6.7)	(8.3)
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.5			0.5			1.5	1.6
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.4			0.4			1.2	1.3
Net Current Period Other Comprehensive Income (Loss)		0.4			0.4			1.2	1.3
Ending Balance in AOCI		(5.5)	(5.9)		(7.0)	(7.4)		(5.5)	(7.0)
Indiana Michigan Power Co [Member] | Pension and OPEB [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		5.2		5.4	1.2		1.3	5.4	1.3
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(0.2)			0.0			(0.4)	(0.1)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(0.1)			0.0			(0.3)	(0.1)
Net Current Period Other Comprehensive Income (Loss)		(0.1)			0.0			(0.3)	(0.1)
Ending Balance in AOCI		5.1	5.2		1.2	1.2		5.1	1.2
Indiana Michigan Power Co [Member] | Accumulated Other Comprehensive Income [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Net Current Period Other Comprehensive Income (Loss)		0.3	0.3	0.3	0.4	0.3	0.5
Indiana Michigan Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member]
Interest Rate
Interest Expense	[2]	0.5			0.5			1.5	1.6
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(0.3)			(0.2)			(0.7)	(0.6)
Amortization of Actuarial (Gains) Losses		0.1			0.2			0.3	0.5
Income Tax (Expense) Benefit		0.0			0.1			0.2	0.3
Indiana Michigan Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Interest Rate
Interest Expense	[2]	0.5			0.5			1.5	1.6
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		0.0			0.0			0.0	0.0
Amortization of Actuarial (Gains) Losses		0.0			0.0			0.0	0.0
Income Tax (Expense) Benefit		0.1			0.1			0.3	0.3
Indiana Michigan Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Pension and OPEB [Member]
Interest Rate
Interest Expense	[2]	0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(0.3)			(0.2)			(0.7)	(0.6)
Amortization of Actuarial (Gains) Losses		0.1			0.2			0.3	0.5
Income Tax (Expense) Benefit		(0.1)			0.0			(0.1)	0.0
Public Service Co Of Oklahoma [Member]
Interest Rate
Interest Expense		22.4			16.2			62.6	44.7
Amortization Of Pension And Other Postretirement Benefit Plans
Income Tax (Expense) Benefit		(31.3)			(2.1)			(41.2)	(3.7)
Net Current Period Other Comprehensive Income (Loss)							(0.1)
Public Service Co Of Oklahoma [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		0.0		0.0	0.0		0.1	0.0	0.1
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.0			0.0			0.0	(0.1)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.0			0.0			0.0	(0.1)
Net Current Period Other Comprehensive Income (Loss)		0.0			0.0			0.0	(0.1)
Ending Balance in AOCI		0.0	0.0		0.0	0.0		0.0	0.0
Public Service Co Of Oklahoma [Member] | Accumulated Other Comprehensive Income [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Net Current Period Other Comprehensive Income (Loss)							(0.1)
Public Service Co Of Oklahoma [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Interest Rate
Interest Expense	[2]	0.0			0.0			0.0	(0.1)
Amortization Of Pension And Other Postretirement Benefit Plans
Income Tax (Expense) Benefit		0.0			0.0			0.0	0.0
Southwestern Electric Power Co [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		5.9		6.7	1.9		1.9	6.7	1.9
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Interest Rate
Interest Expense		35.2			31.7			102.0	92.4
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(0.5)			(0.1)			(1.5)	(0.1)
Income Tax (Expense) Benefit		(17.8)			6.3			(21.0)	19.0
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(0.4)			(0.1)			(1.2)	(0.1)
Regulatory Assets, Noncurrent								(3.1)	91.5
Net Current Period Other Comprehensive Income (Loss)		(0.4)	(0.5)	(0.3)	(0.1)			(1.2)	(0.1)
Ending Balance in AOCI		5.5	5.9		1.8	1.9		5.5	1.8
Southwestern Electric Power Co [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		1.2		1.2	0.5		(0.3)	1.2	(0.3)
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		0.0			0.4			0.0	1.4
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		0.0			0.3			0.0	1.1
Net Current Period Other Comprehensive Income (Loss)		0.0			0.3			0.0	1.1
Ending Balance in AOCI		1.2	1.2		0.8	0.5		1.2	0.8
Southwestern Electric Power Co [Member] | Pension and OPEB [Member]
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance in AOCI		4.7		5.5	1.4		$ 2.2	5.5	2.2
Change in Fair Value Recognized in AOCI		0.0			0.0			0.0	0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Reclassification from AOCI, before Income Tax (Expense) Benefit		(0.5)			(0.5)			(1.5)	(1.5)
Reclassification from AOCI, Net of Income Tax (Expense) Benefit		(0.4)			(0.4)			(1.2)	(1.2)
Net Current Period Other Comprehensive Income (Loss)		(0.4)			(0.4)			(1.2)	(1.2)
Ending Balance in AOCI		4.3	4.7		1.0	$ 1.4		4.3	1.0
Southwestern Electric Power Co [Member] | Accumulated Other Comprehensive Income [Member]
Amortization Of Pension And Other Postretirement Benefit Plans
Net Current Period Other Comprehensive Income (Loss)		(0.4)	$ (0.5)	$ (0.3)	(0.1)
Southwestern Electric Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member]
Interest Rate
Interest Expense	[2]				0.4				1.4
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(0.5)			(0.5)			(1.5)	(1.5)
Income Tax (Expense) Benefit		(0.1)			0.0			(0.3)	0.0
Southwestern Electric Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Interest Rate [Member]
Interest Rate
Interest Expense	[2]				0.4				1.4
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		0.0			0.0			0.0	0.0
Income Tax (Expense) Benefit		0.0			0.1			0.0	0.3
Southwestern Electric Power Co [Member] | Reclassifications from Accumulated Other Comprehensive Income [Member] | Pension and OPEB [Member]
Interest Rate
Interest Expense	[2]				0.0				0.0
Amortization Of Pension And Other Postretirement Benefit Plans
Amortization of Prior Service Cost (Credit)		(0.5)			(0.5)			(1.5)	(1.5)
Income Tax (Expense) Benefit		$ (0.1)			$ (0.1)			$ (0.3)	$ (0.3)

[1] The change in fair value includes $(4) million and $(1) million, respectively, for the three months ended September 30, 2022 and 2021 and $(9) million and $(5) million, respectively, for the nine months ended September 30, 2022 and 2021 related to AEP's investment in joint venture wind farms acquired as part of the purchase of Sempra Renewables LLC.

[2] Amounts reclassified to the referenced line item on the statements of income.