Acquisitions and Dispositions (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) GWh MW	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Customers	$ 949.8		$ 1,145.1
Net Property, Plant and Equipment	73,347.0		73,339.1
Assets Held for Sale	1,396.3		0.0
Accounts Payable, Current	2,269.3		2,670.8
Liabilities Held for Sale	67.2		0.0
North Central Wind Energy Facilities
Payments to Acquire Property, Plant, and Equipment	2,000.0
Transmission Operations [Member]
Enterprise Value	2,850.0
Transmission Operations [Member] | Proceeds for KY Operations
Enterprise Value	2,646.0
Generation And Marketing [Member] | Competitive Contracted Renewable Portfolio
gain (loss) on Disposition of Business net of Tax	(88.5)
Customers	16.9
Net Property, Plant and Equipment	1,404.7
Disposal Group, Including Discontinued Operation, Other Assets	63.2
Disposal Group, Including Discontinued Operation, Assets	1,484.8
Assets Held for Sale	1,396.3
Accounts Payable, Current	6.8
Asset Retirement Obligation	30.6
Operating Lease, Liability	20.1
Disposal Group, Including Discontinued Operation, Other Liabilities, Current	9.7
Liabilities Held for Sale	67.2
Generation And Marketing [Member] | Competitive Contracted Renewables
Enterprise Value	$ 1,500.0
Contracted Renewables GWs | GWh	1.4
Competitive Contracted Renewables NBV	$ 1,200.0
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	$ 247.0
Indemnification	70.0
Proceeds from Sale of Productive Assets	1,200.0
Gain (Loss) on Disposition of Business	112.0
gain (loss) on Disposition of Business net of Tax	88.0
Deferred Tax Assets, Gross	23.5
Other Noncontrolling Interests	192.0
EQ Method Investments	247.0
Vertically Integrated Utilities [Member]
Enterprise Value	2,850.0
Pretax Reduction in Investment Basis	$ 335.0		363.0
Vertically Integrated Utilities [Member] | Sundance [Member]
Wind Generation MWs | MW	199
Vertically Integrated Utilities [Member] | Maverick [Member]
Wind Generation MWs | MW	287
Vertically Integrated Utilities [Member] | Traverse [Member]
Wind Generation MWs | MW	998
Vertically Integrated Utilities [Member] | Traverse [Member] | North Central Wind Energy Facilities
Payments to Acquire Property, Plant, and Equipment	$ 1,200.0
Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities
Wind Generation MWs | MW	1,484
Public Service Co Of Oklahoma [Member]
Percentage of an Asset Acquired	45.50%
Payments to Acquire Property, Plant, and Equipment	$ 146.0
Customers	61.4		70.1
Net Property, Plant and Equipment	5,864.3		5,626.5
Accounts Payable, Current	$ 155.7		202.9
Southwestern Electric Power Co [Member]
Percentage of an Asset Acquired	54.50%
Payments to Acquire Property, Plant, and Equipment	$ 0.0	$ (658.0)
Customers	33.9		38.8
Net Property, Plant and Equipment	8,342.6		8,262.2
Accounts Payable, Current	188.9		213.1
AEP Transmission Co [Member]
Customers	51.9		46.9
Net Property, Plant and Equipment	13,712.0		13,339.9
Accounts Payable, Current	$ 421.7		$ 427.8