Business Segments (Details) - USD ($) $ in Millions		3 Months Ended						6 Months Ended
		Jun. 30, 2022		Mar. 31, 2022	Jun. 30, 2021		Mar. 31, 2021	Jun. 30, 2022		Jun. 30, 2021		Dec. 31, 2021
Reportable Segment Information
Revenue from Contracts with Customers		$ 4,639.7			$ 3,826.5			$ 9,232.3		$ 8,107.6
Revenue from Related Parties		0.0			0.0			0.0		0.0
Revenues		4,639.7			3,826.5			9,232.3		8,107.6
Net Income (Loss)		520.8		$ 718.1	573.8		$ 578.8	1,238.9		1,152.6
Balance Sheet Information
Total Property, Plant and Equipment		90,471.0						90,471.0				$ 86,806.4
Accumulated Depreciation and Amortization		21,762.8						21,762.8				20,805.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		68,708.2						68,708.2				66,001.3
Total Assets	[1]	90,861.3						90,861.3				87,668.7
Long-term Debt Due Within One Year	[2]	2,476.7						2,476.7				2,153.8
Long-term Debt	[3]	32,982.7						32,982.7				31,300.7
Total Long-term Debt Outstanding	[4]	35,459.4						35,459.4				33,454.5
Interest Expense		327.6			301.6			641.0		591.8
Income Tax (Expense) Benefit		54.0			61.2			106.8		115.7
Reclassification out of Accumulated Other Comprehensive Income [Member]
Balance Sheet Information
Interest Expense	[5]	1.1			1.8			2.2		3.3
Income Tax (Expense) Benefit		(34.4)			(2.3)			(44.9)		(38.4)
Interest Rate [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Balance Sheet Information
Interest Expense	[5]	1.1			1.8			2.2		3.3
Income Tax (Expense) Benefit		0.3			0.3			0.5		0.7
Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		2,595.0			2,224.6			5,241.8		4,729.1
Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		1,296.8			1,089.6			2,539.0		2,171.9
Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		654.4			422.5			1,263.9		1,024.2
Generation and Marketing Revenues [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[5]	0.1			(0.1)					0.7
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	[5]	0.0			0.0					0.0
Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		93.5			89.8			187.6		182.4
Revenues		135.7	[6]		29.1	[7],[8]		301.1	[9],[10]	33.9	[11],[12]
AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers										0.1
Revenues from Related Parties, Net of Provisions for Refund		287.1			281.4			602.5		567.0
Revenue from Related Parties		333.9			299.0			658.9		584.6
Revenues		364.4			365.5			764.8		727.2
Net Income (Loss)		118.5		$ 155.4	148.6		$ 151.7	273.9		300.3
Balance Sheet Information
Total Property, Plant and Equipment		13,337.0						13,337.0				12,708.5
Accumulated Depreciation and Amortization		887.8						887.8				772.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		12,449.2						12,449.2				11,935.7
Total Assets	[13]	13,089.8						13,089.8				12,524.4
Long-term Debt Due Within One Year		104.0						104.0				104.0
Long-term Debt		4,781.6						4,781.6				4,239.9
Total Long-term Debt Outstanding		4,885.6						4,885.6				4,343.9
Interest Income		0.2			0.1			0.3		0.2
Interest Expense		39.3			34.3			77.0		68.4
Income Tax (Expense) Benefit		34.3			39.1			79.8		78.7
AEP Transmission Co [Member] | Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.1
Revenues		0.0	[14]		0.0	[15]		0.0	[16]	0.0	[17]
AEP Transmission Co [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		85.6			86.1			172.6		162.4
Balance Sheet Information
Revenue from Contract with Customers, Net of Provisions for Refund, Including Assessed Tax		77.3			84.1			162.3		160.1
Reconciling Adjustments [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Revenue from Related Parties		(373.3)			(367.8)			(765.5)		(736.2)
Revenues		(373.3)			(367.8)			(765.5)		(736.2)
Net Income (Loss)		0.0			0.0			0.0		0.0
Balance Sheet Information
Total Assets	[1],[18]	(6,750.2)						(6,750.2)				(4,409.1)
Reconciling Adjustments [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		(2.0)	[6]		(2.0)	[7],[8]		(4.9)	[9],[10]	(5.6)	[11],[12]
Reconciling Adjustments [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Revenue from Related Parties		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	[13],[19]	(4,991.1)						(4,991.1)				(4,429.4)
Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Related Parties		53.5			36.0			94.1		68.8
Revenues		2,648.5			2,260.6			5,335.9		4,797.9
Net Income (Loss)		303.3			228.8			602.5		500.2
Balance Sheet Information
Total Assets	[1]	48,926.6						48,926.6				46,974.2
Vertically Integrated Utilities [Member] | Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		2,595.0			2,224.6			5,241.8		4,729.1
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		0.1	[6]		0.3	[7],[8]		0.1	[9],[10]	0.3	[11],[12]
Transmission And Distribution Utilities [Member]
Reportable Segment Information
Revenue from Related Parties		4.8			13.8			9.4		19.6
Revenues		1,301.6			1,103.4			2,548.4		2,191.5
Net Income (Loss)		164.8			153.7			317.6		268.1
Balance Sheet Information
Total Assets	[1]	22,444.5						22,444.5				21,120.2
Transmission And Distribution Utilities [Member] | Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		1,296.8			1,089.6			2,539.0		2,171.9
Transmission And Distribution Utilities [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		6.8	[6]		4.0	[7],[8]		13.1	[9],[10]	9.3	[11],[12]
AEP Transmission Holdco [Member]
Reportable Segment Information
Revenue from Related Parties		299.7			291.8			627.7		580.9
Revenues		378.8			378.2			790.2		755.2
Net Income (Loss)		142.7			169.6			316.4		342.8
Balance Sheet Information
Total Assets	[1]	14,472.1						14,472.1				13,873.3
AEP Transmission Holdco [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		79.1			86.4			162.5		174.3
Generation And Marketing [Member]
Reportable Segment Information
Revenue from Related Parties		5.2			14.1			15.0		46.6
Revenues		659.6			436.6			1,278.9		1,070.8
Net Income (Loss)		65.9			46.5			181.9		84.7
Balance Sheet Information
Total Assets	[1]	5,202.3						5,202.3				4,263.6
Generation And Marketing [Member] | Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		654.4			422.5			1,263.9		1,024.2
Generation And Marketing [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		128.5	[6],[20]		24.6	[7],[8]		287.7	[9],[10]	24.6	[11],[12]
All Other [Member]
Reportable Segment Information
Revenue from Related Parties	[21]	10.1			12.1			19.3		20.3
Revenues	[21]	24.5			15.5			44.4		28.4
Net Income (Loss)	[21]	(155.9)			(24.8)			(179.5)		(43.2)
Balance Sheet Information
Total Assets	[1],[21],[22]	6,566.0						6,566.0				5,846.5
All Other [Member] | Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[21]	14.4			3.4			25.1		8.1
Revenues		2.3	[6]		2.2	[7],[8]		5.1	[9],[10]	5.3	[11],[12]
State Transcos [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers										0.1
Revenue from Related Parties		287.1			281.4			602.5		567.0
Revenues		364.4			365.5			764.8		727.2
Net Income (Loss)		118.4			148.5			273.8		300.2
Balance Sheet Information
Total Assets	[13]	13,152.5						13,152.5				12,564.3
State Transcos [Member] | AEP Transmission Co [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		77.3			84.1			162.3		160.1
AEPTCo Parent [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0			0.0			0.0		0.0
Revenue from Related Parties		0.0			0.0			0.0		0.0
Revenues		0.0			0.0			0.0		0.0
Net Income (Loss)		0.1	[23]		$ 0.1			0.1	[23]	$ 0.1
Balance Sheet Information
Total Assets	[13],[24]	$ 4,928.4						$ 4,928.4				$ 4,389.5

[1] Amount includes Assets Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

[2] Amount excludes $415 million and $200 million as of June 30, 2022 and December 31, 2021, respectively, of Long-term Debt Due Within One Year classified as Liabilities Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

[3] Amount excludes $688 million and $903 million as of June 30, 2022 and December 31, 2021, respectively, of Long-term Debt classified as Liabilities Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

[4] The book value amounts exclude Long-term Debt of $1.1 billion and $1.1 billion as of June 30, 2022 and December 31, 2021, respectively, classified as Liabilities Held for Sale on the balance sheets. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

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

[6] Amounts include affiliated and nonaffiliated revenues.

[7] Amounts include affiliated and nonaffiliated revenues

[8] Generation & Marketing includes economic hedge activity.

[9] Amounts include affiliated and nonaffiliated revenues.

[10] Generation & Marketing includes economic hedge activity.

[11] Amounts include affiliated and nonaffiliated revenues.

[12] Generation & Marketing includes economic hedge activity.

[13] Amount includes Assets Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

[14] Amounts include affiliated and nonaffiliated revenues.

[15] Amounts include affiliated and nonaffiliated revenues.

[16] Amounts include affiliated and nonaffiliated revenues.

[17] Amounts include affiliated and nonaffiliated revenues.

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

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

[20] Generation & Marketing includes economic hedge activity.

[21] 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.

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

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

[24] Includes the elimination of AEPTCo Parent’s investments in State Transcos.