Business Segments (Details) - USD ($) $ in Millions		3 Months Ended						6 Months Ended
		Jun. 30, 2023		Mar. 31, 2023	Jun. 30, 2022		Mar. 31, 2022	Jun. 30, 2023		Jun. 30, 2022		Dec. 31, 2022
Reportable Segment Information
Interest Expense		$ 460.0			$ 327.6			$ 875.7		$ 641.0
Revenue from Contracts with Customers		4,372.5			4,639.7			9,063.4		9,232.3
Revenues		4,372.5			4,639.7			9,063.4		9,232.3
Net Income (Loss)		516.1		$ 400.4	520.8		$ 718.1	916.5		1,238.9
Income Tax (Expense) Benefit		28.6			54.0			39.0		106.8
Balance Sheet Information
Total Property, Plant and Equipment		98,415.8						98,415.8				$ 97,021.4
Accumulated Depreciation and Amortization		23,734.4						23,734.4				23,682.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		74,681.4						74,681.4				73,339.1
Total Assets		96,002.1	[1]					96,002.1	[1]			93,403.3
Long-term Debt Due Within One Year		3,380.3						3,380.3				2,486.4
Long-term Debt		36,762.0						36,762.0				34,314.6
Total Long-term Debt Outstanding		40,142.3						40,142.3				36,801.0
Related Party
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reportable Segment Information
Interest Expense	[2]	(0.5)			1.1			0.2		2.2
Income Tax (Expense) Benefit		5.1			(34.4)			14.2		(44.9)
Interest Rate [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reportable Segment Information
Interest Expense	[2]	(0.5)			1.1			0.2		2.2
Income Tax (Expense) Benefit		(0.1)			0.3			0.0		0.5
Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		2,629.0			2,595.0			5,445.3		5,241.8
Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		1,330.8			1,296.8			2,786.1		2,539.0
Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		318.2			654.4			645.1		1,263.9
Generation and Marketing Revenues [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[2]				0.1
Generation and Marketing Revenues [Member] | Interest Rate [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[2]				0.0
Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		94.5			93.5			186.9		187.6
Revenues		(128.8)	[3]		135.7	[4],[5]		(258.7)	[6],[7]	301.1	[8],[9]
AEP Transmission Co [Member]
Reportable Segment Information
Interest Expense		50.7			39.3			95.9		77.0
Interest Income		2.6			0.2			4.1		0.3
Revenues from Related Parties, Net of Provisions for Refund		357.5			287.1			710.1		602.5
Revenues		444.9			364.4			886.5		764.8
Net Income (Loss)		175.7		$ 162.7	118.5		$ 155.4	338.4		273.9
Income Tax (Expense) Benefit		49.1			34.3			96.8		79.8
Balance Sheet Information
Total Property, Plant and Equipment		15,188.5						15,188.5				14,366.9
Accumulated Depreciation and Amortization		1,150.8						1,150.8				1,027.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		14,037.7						14,037.7				13,339.9
Total Assets		14,576.5						14,576.5				13,814.2
Long-term Debt Due Within One Year		60.0						60.0				60.0
Long-term Debt		5,413.0						5,413.0				4,722.8
Total Long-term Debt Outstanding		5,473.0						5,473.0				4,782.8
AEP Transmission Co [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		365.8			333.9			723.2		658.9
AEP Transmission Co [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		0.0	[10]		0.0	[11]		0.0	[12]	0.0	[13]
AEP Transmission Co [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contract with Customers, Net of Provisions for Refund, Including Assessed Tax		87.4			77.3			176.4		162.3
Revenue from Contracts with Customers		90.2			85.6			180.2		172.6
Reconciling Adjustments [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Revenues		(464.2)			(373.3)			(907.9)		(765.5)
Net Income (Loss)		0.0			0.0			0.0		0.0
Balance Sheet Information
Total Assets	[14]	(5,878.0)	[1]					(5,878.0)	[1]			(5,783.0)
Reconciling Adjustments [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		(464.2)			(373.3)			(907.9)		(765.5)
Reconciling Adjustments [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		(2.0)	[3]		(2.0)	[4],[5]		(2.9)	[6],[7]	(4.9)	[8],[9]
Reconciling Adjustments [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Revenues		0.0			0.0			0.0		0.0
Net Income (Loss)		0.0			0.0			0.0		0.0
Balance Sheet Information
Total Assets	[15]	(5,591.9)						(5,591.9)				(4,878.8)
Reconciling Adjustments [Member] | AEP Transmission Co [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenues		2,674.5			2,648.5			5,532.3		5,335.9
Net Income (Loss)		278.4			303.3			540.6		602.5
Balance Sheet Information
Total Assets		51,047.3	[1]					51,047.3	[1]			49,761.8
Vertically Integrated Utilities [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		45.5			53.5			87.0		94.1
Vertically Integrated Utilities [Member] | Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		2,629.0			2,595.0			5,445.3		5,241.8
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		0.1	[3]		0.1	[4],[5]		0.0	[6],[7]	0.1	[8],[9]
Transmission And Distribution Utilities [Member]
Reportable Segment Information
Revenues		1,340.2			1,301.6			2,804.4		2,548.4
Net Income (Loss)		176.7			164.8			302.4		317.6
Balance Sheet Information
Total Assets		23,900.0	[1]					23,900.0	[1]			22,920.2
Transmission And Distribution Utilities [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		9.4			4.8			18.3		9.4
Transmission And Distribution Utilities [Member] | Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		1,330.8			1,296.8			2,786.1		2,539.0
Transmission And Distribution Utilities [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		6.1	[3]		6.8	[4],[5]		17.2	[6],[7]	13.1	[8],[9]
AEP Transmission Holdco [Member]
Reportable Segment Information
Revenues		458.6			378.8			914.1		790.2
Net Income (Loss)		197.3			142.7			379.7		316.4
Balance Sheet Information
Total Assets		16,023.5	[1]					16,023.5	[1]			15,215.8
AEP Transmission Holdco [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		370.3			299.7			735.7		627.7
AEP Transmission Holdco [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		88.3			79.1			178.4		162.5
Generation And Marketing [Member]
Reportable Segment Information
Revenues		331.4			659.6			658.4		1,278.9
Net Income (Loss)		(38.6)			65.9			(195.0)		181.9
Balance Sheet Information
Total Assets		4,457.9	[1]					4,457.9	[1]			4,520.1
Generation And Marketing [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		13.2			5.2			13.3		15.0
Generation And Marketing [Member] | Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		318.2			654.4			645.1		1,263.9
Generation And Marketing [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		(135.2)	[3],[16]		128.5	[4],[5]		(276.2)	[6],[7]	287.7	[8],[9]
All Other [Member]
Reportable Segment Information
Revenues	[17]	32.0			24.5			62.1		44.4
Net Income (Loss)	[17]	(97.7)			(155.9)			(111.2)		(179.5)
Balance Sheet Information
Total Assets	[17],[18]	6,451.4	[1]					6,451.4	[1]			6,768.4
All Other [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers	[17]	25.8			10.1			53.6		19.3
All Other [Member] | Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[17]	6.2			14.4			8.5		25.1
Revenues		2.2	[3]		2.3	[4],[5]		3.2	[6],[7]	5.1	[8],[9]
State Transcos [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenues		444.9			364.4			886.5		764.8
Net Income (Loss)		174.2			118.4			335.8		273.8
Balance Sheet Information
Total Assets		14,626.3						14,626.3				13,875.6
State Transcos [Member] | AEP Transmission Co [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		357.5			287.1			710.1		602.5
State Transcos [Member] | AEP Transmission Co [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		87.4			77.3			176.4		162.3
AEPTCo Parent [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Revenues		0.0			0.0			0.0		0.0
Net Income (Loss)	[19]	1.5			0.1			2.6		0.1
Balance Sheet Information
Total Assets	[20]	5,542.1						5,542.1				$ 4,817.4
AEPTCo Parent [Member] | AEP Transmission Co [Member] | Related Party
Reportable Segment Information
Revenue from Contracts with Customers		$ 0.0			$ 0.0			$ 0.0		$ 0.0

[1] Amount includes Assets Held for Sale on the balance sheet. See “Planned Disposition of the Competitive Contracted Renewables Portfolio” section of Note 6 for additional information.

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

[3] Amounts include affiliated and nonaffiliated revenues.

[4] Amounts include affiliated and nonaffiliated revenues

[5] Generation & Marketing includes economic hedge activity.

[6] Amounts include affiliated and nonaffiliated revenues.

[7] Generation & Marketing includes economic hedge activity.

[8] Amounts include affiliated and nonaffiliated revenues.

[9] Generation & Marketing includes economic hedge activity.

[10] Amounts include affiliated and nonaffiliated revenues.

[11] Amounts include affiliated and nonaffiliated revenues.

[12] Amounts include affiliated and nonaffiliated revenues.

[13] Amounts include affiliated and nonaffiliated revenues.

[14] Reconciling Adjustments for Total Assets primarily include elimination of intercompany advances to affiliates and intercompany accounts receivable.

[15] Primarily relates to the elimination of Notes Receivable from the State Transcos.

[16] Generation & Marketing includes economic hedge activity.

[17] Corporate and Other primarily includes the purchasing of receivables from certain AEP utility subsidiaries. This segment also includes Parent’s guarantee revenue received from affiliates, investment income, interest income, interest expense and other nonallocated costs.

[18] Includes elimination of AEP Parent’s investments in wholly-owned subsidiary companies.

[19] Includes the elimination of AEPTCo Parent’s equity earnings in the State Transcos.

[20] Primarily relates to Notes Receivable from the State Transcos.