Acquisitions and Dispositions (Details)		3 Months Ended	6 Months Ended		9 Months Ended
		Jun. 30, 2024 USD ($) MW	Jun. 30, 2024 USD ($) MW	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Customers		$ 1,081,100,000	$ 1,081,100,000			$ 1,029,900,000
Net Property, Plant and Equipment		78,860,400,000	78,860,400,000			76,693,400,000
Assets Held for Sale		353,200,000	353,200,000			0
Accounts Payable, Current		2,331,500,000	2,331,500,000			2,032,500,000
Deferred Income Tax Liabilities, Net		9,786,400,000	9,786,400,000			9,415,700,000
Asset Retirement Obligation	[1],[2],[3],[4],[5],[6]	3,713,300,000	3,713,300,000			3,031,200,000
Liabilities Held for Sale		12,500,000	12,500,000			0
Proceeds from Sale of Equity Method Investments			114,000,000.0	$ 0
Generation & Marketing | New Mexico Renewable Development
Proceeds from Sale of Equity Method Investments			107,000,000
Generation & Marketing | AEP OnSite Partners
AEP OnSite Partners NBV		341,000,000	341,000,000
gain (loss) on Disposition of Business net of Tax		(10,400,000)
Net Property, Plant and Equipment		309,200,000	309,200,000
Disposal Group, Including Discontinued Operation, Other Assets		54,400,000	54,400,000
Disposal Group, Including Discontinued Operation, Assets		363,600,000	363,600,000
Assets Held for Sale		353,200,000	353,200,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Current		12,500,000	12,500,000
Liabilities Held for Sale		12,500,000	12,500,000
Deferred Tax Assets, Gross		$ 2,800,000	2,800,000
Proceeds from Divestiture of Businesses			$ 315,000,000
Generation & Marketing | AEP OnSite Partners | Installed
Solar Generating (MWs) | MW		103	103
Generation & Marketing | AEP OnSite Partners | Under Construction
Solar Generating (MWs) | MW		8	8
Generation & Marketing | Competitive Contracted Renewables
Proceeds from Sale of Productive Assets					$ 1,200,000,000
Gain (Loss) on Disposition of Business				112,000,000
gain (loss) on Disposition of Business net of Tax				88,000,000
Public Service Co Of Oklahoma [Member]
Customers		$ 79,500,000	$ 79,500,000			107,600,000
Net Property, Plant and Equipment		6,294,300,000	6,294,300,000			6,112,300,000
Accounts Payable, Current		211,100,000	211,100,000			159,300,000
Deferred Income Tax Liabilities, Net		908,700,000	908,700,000			831,200,000
Asset Retirement Obligation	[1],[3],[4]	119,700,000	119,700,000			84,200,000
Public Service Co Of Oklahoma [Member] | Vertically Integrated Utilities [Member] | Rock Falls Wind Facility
Payments to Acquire Property, Plant, and Equipment				$ 146,000,000
Southwestern Electric Power Co [Member]
Customers		42,700,000	42,700,000			39,000,000.0
Net Property, Plant and Equipment		8,797,900,000	8,797,900,000			8,558,400,000
Accounts Payable, Current		234,400,000	234,400,000			198,900,000
Deferred Income Tax Liabilities, Net		1,235,200,000	1,235,200,000			1,179,300,000
Asset Retirement Obligation	[1],[2],[3],[4]	272,300,000	272,300,000			281,600,000
AEP Transmission Co [Member]
Customers		88,500,000	88,500,000			82,200,000
Net Property, Plant and Equipment		15,086,000,000	15,086,000,000			14,497,700,000
Accounts Payable, Current		326,200,000	326,200,000			274,700,000
Deferred Income Tax Liabilities, Net		$ 1,204,800,000	$ 1,204,800,000			$ 1,147,700,000

[1] Includes ARO related to wind farms.

[2] Includes ARO related to Sabine and DHLC.

[3] Includes ARO related to ash disposal facilities.

[4] Includes ARO related to asbestos removal.

[5] Includes ARO related to nuclear decommissioning costs for the Cook Plant of $2.1 billion and $2.1 billion as of June 30, 2024 and December 31, 2023, respectively.

[6] Includes ARO related to solar farms.