Variable Interest Entities (Details) - USD ($) $ in Millions	Sep. 30, 2023		Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022		Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
ASSETS
Current Assets	$ 6,736.6				$ 6,775.5
Net Property, Plant and Equipment	75,821.1				73,339.1
Other Noncurrent Assets	12,567.9				13,288.7
Total Assets	95,125.6				93,403.3
LIABILITIES AND EQUITY
Current Liabilities	11,278.1				13,266.3
Noncurrent Liabilities	58,422.8				55,968.7
Equity	25,349.6		$ 24,123.6	$ 23,967.8	24,122.4		$ 24,512.3	$ 24,297.0	$ 24,038.1	$ 22,680.2
Total Liabilities and Equity	95,125.6				93,403.3
Southwestern Electric Power Co [Member]
ASSETS
Current Assets	592.5				812.2
Net Property, Plant and Equipment	8,562.5				8,262.2
Other Noncurrent Assets	1,406.1				1,304.4
Total Assets	10,561.1				10,378.8
LIABILITIES AND EQUITY
Current Liabilities	699.9				947.7
Noncurrent Liabilities	5,982.4				5,756.3
Equity	3,878.8		3,795.5	3,765.2	3,674.8		3,705.1	3,611.1	3,543.8	3,149.8
Total Liabilities and Equity	10,561.1				10,378.8
Indiana Michigan Power Co [Member]
ASSETS
Current Assets	499.0				571.8
Net Property, Plant and Equipment	7,535.7				7,411.5
Other Noncurrent Assets	4,231.8				4,135.6
Total Assets	12,266.5				12,118.9
LIABILITIES AND EQUITY
Current Liabilities	624.0				1,197.1
Noncurrent Liabilities	8,502.3				7,913.5
Equity	3,140.2		3,120.7	3,077.3	3,008.3		2,968.3	2,893.3	2,849.5	2,784.7
Total Liabilities and Equity	12,266.5				12,118.9
AEP Texas Inc. [Member]
ASSETS
Current Assets	624.8				446.9
Net Property, Plant and Equipment	12,590.8				11,681.6
Other Noncurrent Assets	742.1				763.7
Total Assets	13,957.7				12,892.2
LIABILITIES AND EQUITY
Current Liabilities	780.8				1,043.8
Noncurrent Liabilities	8,466.4				7,944.1
Equity	4,710.5		4,334.6	4,051.3	3,904.3		3,850.0	3,755.6	3,664.1	3,594.2
Total Liabilities and Equity	13,957.7				12,892.2
Appalachian Power Co [Member]
ASSETS
Current Assets	1,231.8				1,259.6
Net Property, Plant and Equipment	12,825.1				12,379.2
Other Noncurrent Assets	1,452.8				1,583.4
Total Assets	15,509.7				15,222.2
LIABILITIES AND EQUITY
Current Liabilities	1,544.3				1,390.2
Noncurrent Liabilities	8,739.1				8,856.6
Equity	5,226.3		$ 5,133.1	$ 5,086.9	4,975.4		$ 4,914.0	$ 4,821.1	$ 4,748.0	$ 4,647.9
Total Liabilities and Equity	15,509.7				15,222.2
Sabine Mining Co [Member] | Variable Interest Entities [Member] | Southwestern Electric Power Co [Member]
ASSETS
Current Assets	4.8				108.3
Net Property, Plant and Equipment	0.0				7.2
Other Noncurrent Assets	128.1				130.0
Total Assets	132.9				245.5
LIABILITIES AND EQUITY
Current Liabilities	21.0				25.4
Noncurrent Liabilities	110.6				219.4
Equity	1.3				0.7
Total Liabilities and Equity	132.9				245.5
DCC Fuel [Member] | Variable Interest Entities [Member] | Indiana Michigan Power Co [Member]
ASSETS
Current Assets	59.9				90.2
Net Property, Plant and Equipment	104.1				179.1
Other Noncurrent Assets	51.8				94.0
Total Assets	215.8				363.3
LIABILITIES AND EQUITY
Current Liabilities	59.8				90.0
Noncurrent Liabilities	156.0				273.3
Equity	0.0				0.0
Total Liabilities and Equity	215.8				363.3
AEP Texas Central Transition Funding Co [Member] | AEP Texas Inc. [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	10.0				16.0
AEP Texas Central Transition Funding Co [Member] | Variable Interest Entities [Member] | AEP Texas Inc. [Member]
ASSETS
Current Assets	49.4				27.0
Net Property, Plant and Equipment	0.0				0.0
Other Noncurrent Assets	90.5	[1]			140.9	[2]
Total Assets	139.9				167.9
LIABILITIES AND EQUITY
Current Liabilities	75.3				73.2
Noncurrent Liabilities	60.3				90.4
Equity	4.3				4.3
Total Liabilities and Equity	139.9				167.9
Restoration Funding [Member] | AEP Texas Inc. [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	6.0				7.0
Restoration Funding [Member] | Variable Interest Entities [Member] | AEP Texas Inc. [Member]
ASSETS
Current Assets	20.9				21.1
Net Property, Plant and Equipment	0.0				0.0
Other Noncurrent Assets	151.4	[3]			168.8	[4]
Total Assets	172.3				189.9
LIABILITIES AND EQUITY
Current Liabilities	36.0				31.3
Noncurrent Liabilities	135.1				157.4
Equity	1.2				1.2
Total Liabilities and Equity	172.3				189.9
Appalachian Consumer Rate Relief Funding [Member] | Appalachian Power Co [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	2.0				2.0
Appalachian Consumer Rate Relief Funding [Member] | Variable Interest Entities [Member] | Appalachian Power Co [Member]
ASSETS
Current Assets	4.7				13.5
Net Property, Plant and Equipment	0.0				0.0
Other Noncurrent Assets	145.3	[5]			164.6	[6]
Total Assets	150.0				178.1
LIABILITIES AND EQUITY
Current Liabilities	28.5				29.3
Noncurrent Liabilities	119.6				146.9
Equity	1.9				1.9
Total Liabilities and Equity	150.0				178.1
AEP Credit, Inc. [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	1,259.0				1,181.0
Net Property, Plant and Equipment	0.0				0.0
Other Noncurrent Assets	9.6				9.0
Total Assets	1,268.6				1,190.0
LIABILITIES AND EQUITY
Current Liabilities	1,201.3				1,087.8
Noncurrent Liabilities	0.9				0.9
Equity	66.4				101.3
Total Liabilities and Equity	1,268.6				1,190.0
Protected Cell Of Energy Insurance Services, Inc. [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	202.9				194.5
Net Property, Plant and Equipment	0.0				0.0
Other Noncurrent Assets	0.7				0.3
Total Assets	203.6				194.8
LIABILITIES AND EQUITY
Current Liabilities	54.1				46.4
Noncurrent Liabilities	84.7				79.1
Equity	64.8				69.3
Total Liabilities and Equity	203.6				194.8
Transource Energy [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	32.8				23.5
Net Property, Plant and Equipment	499.8				482.3
Other Noncurrent Assets	4.0				2.7
Total Assets	536.6				508.5
LIABILITIES AND EQUITY
Current Liabilities	21.3				22.8
Noncurrent Liabilities	229.4				218.6
Equity	285.9				267.1
Total Liabilities and Equity	$ 536.6				508.5
Apple Blossom and Black Oak [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets					8.3
Net Property, Plant and Equipment					216.5
Other Noncurrent Assets					13.6
Total Assets					238.4
LIABILITIES AND EQUITY
Current Liabilities					4.5
Noncurrent Liabilities					5.4
Equity					228.5
Total Liabilities and Equity					238.4
Santa Rita East [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets					21.3
Net Property, Plant and Equipment					421.6
Other Noncurrent Assets					0.1
Total Assets					443.0
LIABILITIES AND EQUITY
Current Liabilities					9.6
Noncurrent Liabilities					7.3
Equity					426.1
Total Liabilities and Equity					443.0
Dry Lake Solar Project [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets					4.0
Net Property, Plant and Equipment					142.6
Other Noncurrent Assets					0.3
Total Assets					146.9
LIABILITIES AND EQUITY
Current Liabilities					1.0
Noncurrent Liabilities					0.7
Equity					145.2
Total Liabilities and Equity					$ 146.9

[1] Includes an intercompany item eliminated in consolidation of $10 million.

[2] Includes an intercompany item eliminated in consolidation of $16 million.

[3] Includes an intercompany item eliminated in consolidation of $6 million.

[4] Includes an intercompany item eliminated in consolidation of $7 million.

[5] Includes an intercompany item eliminated in consolidation of $2 million.

[6] Includes an intercompany item eliminated in consolidation of $2 million