Business Segments (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		Dec. 31, 2021
Reportable Segment Information
Revenue from Contracts with Customers		$ 5,526.1				$ 4,623.0				$ 14,758.4		$ 12,730.6
Revenue from Related Parties		0.0				0.0				0.0		0.0
Revenues		5,526.1				4,623.0				14,758.4		12,730.6
Net Income (Loss)		683.3		$ 520.8	$ 718.1	796.9		$ 573.8	$ 578.8	1,922.2		1,949.5
Balance Sheet Information
Total Property, Plant and Equipment		92,105.1								92,105.1				$ 86,806.4
Accumulated Depreciation and Amortization		22,292.0								22,292.0				20,805.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		69,813.1								69,813.1				66,001.3
Total Assets	[1]	91,249.4								91,249.4				87,668.7
Long-term Debt Due Within One Year	[2]	1,403.5								1,403.5				2,153.8
Long-term Debt	[3]	33,646.6								33,646.6				31,300.7
Total Long-term Debt Outstanding	[4]	35,050.1								35,050.1				33,454.5
Interest Expense		360.7				303.7				1,001.7		895.5
Income Tax (Expense) Benefit		(16.1)				69.8				90.7		185.5
Reclassification out of Accumulated Other Comprehensive Income [Member]
Balance Sheet Information
Interest Expense	[5]	0.9				1.5				3.1		4.8
Income Tax (Expense) Benefit		(47.3)				(12.7)				(92.2)		(51.1)
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]	0.9				1.5				3.1		4.8
Income Tax (Expense) Benefit		0.1				0.3				0.6		1.0
Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		3,174.6				2,716.8				8,416.4		7,445.9
Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		1,525.5				1,195.0				4,064.5		3,366.9
Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		733.1				617.4				1,997.0		1,641.6
Generation and Marketing Revenues [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[5]	0.2								0.2		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		92.9				93.8				280.5		276.2
Revenues		128.3	[6]			154.8	[7],[8]			429.4	[9],[10]	188.7	[11],[12]
AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers												0.3
Revenues from Related Parties, Net of Provisions for Refund		331.3				297.6				933.8		864.6
Revenue from Related Parties		340.6				297.7				999.5		882.3
Revenues		418.5				377.0				1,183.3		1,104.2
Net Income (Loss)		152.7		$ 118.5	$ 155.4	145.4		$ 148.6	$ 151.7	426.6		445.7
Balance Sheet Information
Total Property, Plant and Equipment		13,695.0								13,695.0				12,708.5
Accumulated Depreciation and Amortization		952.4								952.4				772.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		12,742.6								12,742.6				11,935.7
Total Assets	[13]	13,319.2								13,319.2				12,524.4
Long-term Debt Due Within One Year		104.0								104.0				104.0
Long-term Debt		4,782.6								4,782.6				4,239.9
Total Long-term Debt Outstanding		4,886.6								4,886.6				4,343.9
Interest Income		0.7				0.2				1.0		0.4
Interest Expense		42.7				36.1				119.7		104.5
Income Tax (Expense) Benefit		44.3				36.7				124.1		115.4
AEP Transmission Co [Member] | Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0				0.2				0.0		0.3
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		89.1				79.2				261.7		241.6
Balance Sheet Information
Revenue from Contract with Customers, Net of Provisions for Refund, Including Assessed Tax		87.2				79.2				249.5		239.3
Reconciling Adjustments [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0				0.0				0.0		0.0
Revenue from Related Parties		(425.0)				(376.0)				(1,190.5)		(1,112.2)
Revenues		(425.0)				(376.0)				(1,190.5)		(1,112.2)
Net Income (Loss)		0.0				0.0				0.0		0.0
Balance Sheet Information
Total Assets	[1],[18]	(6,310.7)								(6,310.7)				(4,409.1)
Reconciling Adjustments [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		(2.0)	[6]			(3.0)	[7],[8]			(6.9)	[9],[10]	(8.6)	[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]	(5,013.1)								(5,013.1)				(4,429.4)
Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Related Parties		51.7				42.5				145.8		111.3
Revenues		3,226.3				2,759.3				8,562.2		7,557.2
Net Income (Loss)		476.9				438.7				1,079.4		938.9
Balance Sheet Information
Total Assets	[1]	49,056.9								49,056.9				46,974.2
Vertically Integrated Utilities [Member] | Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		3,174.6				2,716.8				8,416.4		7,445.9
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		0.2	[6]			(0.9)	[7],[8]			0.3	[9],[10]	(0.6)	[11],[12]
Transmission And Distribution Utilities [Member]
Reportable Segment Information
Revenue from Related Parties		4.7				5.3				14.1		24.9
Revenues		1,530.2				1,200.3				4,078.6		3,391.8
Net Income (Loss)		165.5				155.9				483.1		424.0
Balance Sheet Information
Total Assets	[1]	22,139.7								22,139.7				21,120.2
Transmission And Distribution Utilities [Member] | Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		1,525.5				1,195.0				4,064.5		3,366.9
Transmission And Distribution Utilities [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		5.5	[6]			4.9	[7],[8]			18.6	[9],[10]	14.2	[11],[12]
AEP Transmission Holdco [Member]
Reportable Segment Information
Revenue from Related Parties		349.0				301.3				976.7		882.2
Revenues		430.9				391.6				1,221.1		1,146.8
Net Income (Loss)		171.4				167.9				487.8		510.7
Balance Sheet Information
Total Assets	[1]	14,708.9								14,708.9				13,873.3
AEP Transmission Holdco [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		81.9				90.3				244.4		264.6
Generation And Marketing [Member]
Reportable Segment Information
Revenue from Related Parties		2.3				3.7				17.3		50.3
Revenues		735.4				621.1				2,014.3		1,691.9
Net Income (Loss)		96.2				99.5				278.1		184.2
Balance Sheet Information
Total Assets	[1]	5,376.3								5,376.3				4,263.6
Generation And Marketing [Member] | Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		733.1				617.4				1,997.0		1,641.6
Generation And Marketing [Member] | Other Revenues [Member]
Reportable Segment Information
Revenues		122.8	[6],[20]			150.7	[7],[8]			410.5	[9],[10]	175.3	[11],[12]
All Other [Member]
Reportable Segment Information
Revenue from Related Parties	[21]	17.3				23.2				36.6		43.5
Revenues	[21]	28.3				26.7				72.7		55.1
Net Income (Loss)	[21]	(226.7)				(65.1)				(406.2)		(108.3)
Balance Sheet Information
Total Assets	[1],[21],[22]	6,278.3								6,278.3				5,846.5
All Other [Member] | Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[21]	11.0				3.5				36.1		11.6
Revenues		1.8	[6]			3.1	[7],[8]			6.9	[9],[10]	8.4	[11],[12]
State Transcos [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers												0.3
Revenue from Related Parties		331.3				297.6				933.8		864.6
Revenues		418.5				377.0				1,183.3		1,104.2
Net Income (Loss)		152.6				145.3				426.4		445.5
Balance Sheet Information
Total Assets	[13]	13,359.9								13,359.9				12,564.3
State Transcos [Member] | AEP Transmission Co [Member] | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		87.2				79.2				249.5		239.3
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)	[23]	0.1				$ 0.1				0.2		$ 0.2
Balance Sheet Information
Total Assets	[13],[24]	$ 4,972.4								$ 4,972.4				$ 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 $215 million and $200 million as of September 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 $963 million and $903 million as of September 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 $1.2 billion and $1.1 billion as of September 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.