Acquisitions and Dispositions (Details)		3 Months Ended
		Mar. 31, 2022 USD ($) MW	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Obligations Under Operating Leases		$ 563,300,000		$ 492,800,000
Asset Retirement Obligation, Liabilities Settled	[1],[2],[3],[4],[5]	4,900,000
Additional Paid in Capital		7,964,500,000		7,172,600,000
Property, Plant and Equipment		24,386,600,000		23,088,100,000
Noncontrolling Interests		246,800,000		247,000,000.0
Customers		743,100,000		720,900,000
Materials and Supplies		696,400,000		681,300,000
Property, Plant and Equipment, Net		67,878,000,000		66,001,300,000
Regulatory Assets, Noncurrent		4,087,600,000		4,142,300,000
Assets Held for Sale		2,972,600,000		2,919,700,000
Accounts Payable, Current		1,694,300,000		2,054,600,000
Long-term Debt Due Within One Year	[6]	3,008,400,000		2,153,800,000
Customer Deposits, Current		356,200,000		321,600,000
Deferred Tax Liabilities, Net, Noncurrent		8,324,900,000		8,202,500,000
Long-term Debt	[7]	30,855,700,000		31,300,700,000
Regulatory Liabilities and Deferred Investment Tax Credits		8,486,600,000		8,686,300,000
Liabilities Held for Sale		1,873,700,000		1,880,900,000
Dry Lake Solar Project
Payments to Acquire Property, Plant, and Equipment		0	$ 102,900,000
North Central Wind Energy Facilities
Payments to Acquire Property, Plant, and Equipment		$ 1,207,300,000	0
Mitchell Power Plant
Approximate OVEC Generating Capacity (MWs) | MW		1,560
Dry Lake Solar Project
Percentage of an Asset Acquired		75.00%
Noncash or Part Noncash Acquisition, Other Assets Acquired			18,900,000
Dry Lake Solar Project | Noncontrolling Interest [Member]
Noncash or Part Noncash Acquisition, Other Assets Acquired			18,900,000
North Central Wind Energy Facilities
Payments to Acquire Property, Plant, and Equipment		$ 2,000,000,000
Generation And Marketing [Member] | Dry Lake Solar Project
Payments to Acquire Property, Plant, and Equipment		114,000,000
Generation And Marketing [Member] | Dry Lake Solar Project | Payment at Closing
Payments to Acquire Property, Plant, and Equipment		103,000,000
Generation And Marketing [Member] | Dry Lake Solar Project | Payment When Put in Service
Payments to Acquire Property, Plant, and Equipment		11,000,000
Generation And Marketing [Member] | Dry Lake Solar Project
Property, Plant and Equipment		145,000,000
Noncontrolling Interests		$ 35,000,000
Solar Generation MWs | MW		100
Generation And Marketing [Member] | Dry Lake Solar Project | Noncontrolling Interest [Member]
Noncash or Part Noncash Acquisition, Other Assets Acquired		$ 16,000,000
Vertically Integrated Utilities [Member]
Enterprise Value		2,850,000,000
Proceeds from Divestiture of Businesses		1,400,000,000
Payment for Alleged Future Increased Costs		578,000,000
Reduction of Purchase Price		20,000,000
Customer Refunds due to Disposition		40,000,000
Vertically Integrated Utilities [Member] | Kentucky Power Company and Kentucky Transmission Company
Customers		75,300,000		33,200,000
Materials and Supplies		37,400,000		30,600,000
Property, Plant and Equipment, Net		2,323,100,000		2,302,700,000
Regulatory Assets, Noncurrent		492,700,000		484,700,000
Disposal Group, Including Discontinued Operation, Other Assets		44,100,000		68,500,000
Assets Held for Sale		2,972,600,000		2,919,700,000
Accounts Payable, Current		57,500,000		53,400,000
Long-term Debt Due Within One Year		200,000,000.0		200,000,000.0
Customer Deposits, Current		34,200,000		32,400,000
Deferred Tax Liabilities, Net, Noncurrent		440,900,000		441,600,000
Long-term Debt		903,200,000		903,100,000
Regulatory Liabilities and Deferred Investment Tax Credits		140,200,000		148,100,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Current		97,700,000		102,300,000
Liabilities Held for Sale		$ 1,873,700,000		1,880,900,000
Vertically Integrated Utilities [Member] | Sundance [Member]
Wind Generation MWs | MW		199
Vertically Integrated Utilities [Member] | Sundance [Member] | North Central Wind Energy Facilities
Payments to Acquire Property, Plant, and Equipment		$ 270,000,000
Vertically Integrated Utilities [Member] | Maverick [Member]
Wind Generation MWs | MW		287
Vertically Integrated Utilities [Member] | Maverick [Member] | North Central Wind Energy Facilities
Payments to Acquire Property, Plant, and Equipment		$ 383,000,000
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		$ 1,200,000,000
Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities
Wind Generation MWs | MW		1,484
Transmission Operations [Member]
Enterprise Value		$ 2,850,000,000
Payment for Alleged Future Increased Costs		578,000,000
Reduction of Purchase Price		20,000,000
Customer Refunds due to Disposition		40,000,000
Transmission Operations [Member] | Kentucky Transmission Company
Customers		1,800,000		1,500,000
Materials and Supplies		0		0
Property, Plant and Equipment, Net		165,800,000		165,300,000
Regulatory Assets, Noncurrent		0		0
Disposal Group, Including Discontinued Operation, Other Assets		2,300,000		1,100,000
Assets Held for Sale		169,900,000		167,900,000
Accounts Payable, Current		1,100,000		1,100,000
Long-term Debt Due Within One Year		0		0
Customer Deposits, Current		0		0
Deferred Tax Liabilities, Net, Noncurrent		15,800,000		15,400,000
Long-term Debt		0		0
Regulatory Liabilities and Deferred Investment Tax Credits		7,800,000		7,600,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Current		2,900,000		3,500,000
Liabilities Held for Sale		$ 27,600,000		27,600,000
Public Service Co Of Oklahoma [Member]
Percentage of an Asset Acquired		45.50%
Obligations Under Operating Leases		$ 100,900,000		62,200,000
Asset Retirement Obligation, Liabilities Settled	[3],[4]	0
Additional Paid in Capital		1,039,000,000		1,039,000,000
Property, Plant and Equipment		2,375,500,000		1,802,400,000
Payments to Acquire Property, Plant, and Equipment		(549,300,000)	0
Customers		40,700,000		41,500,000
Materials and Supplies		63,100,000		56,200,000
Property, Plant and Equipment, Net		5,404,500,000		4,802,800,000
Regulatory Assets, Noncurrent		1,042,000,000		1,037,400,000
Accounts Payable, Current		127,700,000		157,400,000
Long-term Debt Due Within One Year		625,500,000		125,500,000
Customer Deposits, Current		58,200,000		56,200,000
Deferred Tax Liabilities, Net, Noncurrent		779,000,000.0		782,300,000
Long-term Debt		1,788,100,000		1,788,000,000
Regulatory Liabilities and Deferred Investment Tax Credits		831,300,000		835,300,000
Public Service Co Of Oklahoma [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities
Obligations Under Operating Leases		70,600,000		30,600,000
Property, Plant and Equipment		887,000,000
Public Service Co Of Oklahoma [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities | Sundance [Member]
Obligations Under Operating Leases		12,600,000		12,600,000
Public Service Co Of Oklahoma [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities | Maverick [Member]
Obligations Under Operating Leases		18,000,000.0		18,000,000.0
Public Service Co Of Oklahoma [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities | Traverse [Member]
Obligations Under Operating Leases		$ 40,000,000.0		0
Southwestern Electric Power Co [Member]
Percentage of an Asset Acquired		54.50%
Obligations Under Operating Leases		$ 124,200,000		77,700,000
Asset Retirement Obligation, Liabilities Settled	[2],[3],[4]	4,100,000
Additional Paid in Capital		1,442,200,000		1,092,200,000
Property, Plant and Equipment		5,434,300,000		4,734,500,000
Noncontrolling Interests		100,000		(100,000)
Payments to Acquire Property, Plant, and Equipment		(658,000,000.0)	$ 0
Customers		31,500,000		35,800,000
Materials and Supplies		84,300,000		81,900,000
Property, Plant and Equipment, Net		8,087,300,000		7,400,100,000
Regulatory Assets, Noncurrent		962,300,000		1,005,300,000
Accounts Payable, Current		125,100,000		163,600,000
Long-term Debt Due Within One Year		6,200,000		6,200,000
Customer Deposits, Current		64,100,000		62,400,000
Deferred Tax Liabilities, Net, Noncurrent		1,084,500,000		1,087,600,000
Long-term Debt		3,387,900,000		3,389,000,000
Regulatory Liabilities and Deferred Investment Tax Credits		822,100,000		806,900,000
Southwestern Electric Power Co [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities
Obligations Under Operating Leases		84,600,000		36,700,000
Property, Plant and Equipment		1,100,000,000
Southwestern Electric Power Co [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities | Sundance [Member]
Obligations Under Operating Leases		15,000,000.0		15,100,000
Southwestern Electric Power Co [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities | Maverick [Member]
Obligations Under Operating Leases		21,600,000		21,600,000
Southwestern Electric Power Co [Member] | Vertically Integrated Utilities [Member] | North Central Wind Energy Facilities | Traverse [Member]
Obligations Under Operating Leases		$ 48,000,000.0		0
Kentucky Power Co [Member] | Mitchell Power Plant
Ownership Interest in Mitchell Power Plant		50.00%
Wheeling Power Company | Mitchell Power Plant
Ownership Interest in Mitchell Power Plant		50.00%
AEP Transmission Co [Member]
Obligations Under Operating Leases		$ 1,900,000		1,300,000
Customers		29,500,000		22,500,000
Materials and Supplies		10,100,000		9,300,000
Property, Plant and Equipment, Net		12,163,800,000		11,935,700,000
Regulatory Assets, Noncurrent		6,400,000		8,500,000
Assets Held for Sale		169,900,000		167,900,000
Accounts Payable, Current		295,900,000		460,100,000
Long-term Debt Due Within One Year		104,000,000.0		104,000,000.0
Deferred Tax Liabilities, Net, Noncurrent		990,000,000.0		962,900,000
Long-term Debt		4,240,500,000		4,239,900,000
Regulatory Liabilities and Deferred Investment Tax Credits		660,500,000		644,100,000
Liabilities Held for Sale		27,600,000		$ 27,600,000
AEP Transmission Co [Member] | Transmission Operations [Member]
Proceeds from Divestiture of Businesses		$ 1,400,000,000

[1] Includes $19 million and $18 million as of March 31, 2022 and December 31, 2021, respectively, of ARO classified as Liabilities Held for Sale on the balance sheets. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

[2] Includes ARO related to Sabine and DHLC.

[3] Includes ARO related to asbestos removal.

[4] Includes ARO related to ash disposal facilities.

[5] Includes ARO related to nuclear decommissioning costs for the Cook Plant of $1.94 billion and $1.93 billion as of March 31, 2022 and December 31, 2021, respectively.

[6] Amount excludes $200 million and $200 million as of March 31, 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.

[7] Amount excludes $903 million and $903 million as of March 31, 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.