Variable Interest Entities (Details) - USD ($) $ in Millions	Sep. 30, 2024		Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023		Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
ASSETS
Current Assets	$ 6,020.8				$ 6,082.1
Net Property, Plant and Equipment	80,073.8				76,693.4
TOTAL OTHER NONCURRENT ASSETS	14,024.5				13,908.5
Total Assets	100,119.1				96,684.0
LIABILITIES AND EQUITY
Current Liabilities	10,647.6				11,583.6
Noncurrent Liabilities	62,746.9				59,772.0
Equity	26,658.8		$ 26,175.7	$ 25,843.7	25,285.9		$ 25,349.6	$ 24,123.6	$ 23,967.8	$ 24,122.4
Total Liabilities and Equity	100,119.1				96,684.0
Southwestern Electric Power Co [Member]
ASSETS
Current Assets	459.5				541.3
Net Property, Plant and Equipment	8,908.2				8,558.4
TOTAL OTHER NONCURRENT ASSETS	1,460.7				1,457.9
Total Assets	10,828.4				10,557.6
LIABILITIES AND EQUITY
Current Liabilities	947.2				686.9
Noncurrent Liabilities	6,085.1				6,100.3
Equity	3,796.1		3,758.3	3,928.4	3,770.4		3,878.8	3,795.5	3,765.2	3,674.8
Total Liabilities and Equity	10,828.4				10,557.6
Indiana Michigan Power Co [Member]
ASSETS
Current Assets	573.6				528.0
Net Property, Plant and Equipment	7,773.0				7,629.0
TOTAL OTHER NONCURRENT ASSETS	5,321.3				4,651.0
Total Assets	13,667.9				12,808.0
LIABILITIES AND EQUITY
Current Liabilities	950.3				830.2
Noncurrent Liabilities	9,327.2				8,837.6
Equity	3,390.4		3,250.5	3,247.8	3,140.2		3,140.2	3,120.7	3,077.3	3,008.3
Total Liabilities and Equity	13,667.9				12,808.0
AEP Texas Inc. [Member]
ASSETS
Current Assets	704.4				520.1
Net Property, Plant and Equipment	13,650.8				12,774.0
TOTAL OTHER NONCURRENT ASSETS	689.9				696.6
Total Assets	15,045.1				13,990.7
LIABILITIES AND EQUITY
Current Liabilities	931.1				749.4
Noncurrent Liabilities	9,120.4				8,445.2
Equity	4,993.6		5,011.9	4,879.7	4,796.1		4,710.5	4,334.6	4,051.3	3,904.3
Total Liabilities and Equity	15,045.1				13,990.7
Appalachian Power Co [Member]
ASSETS
Current Assets	1,037.7				1,059.0
Net Property, Plant and Equipment	13,404.8				12,931.5
TOTAL OTHER NONCURRENT ASSETS	1,846.9				1,721.4
Total Assets	16,289.4				15,711.9
LIABILITIES AND EQUITY
Current Liabilities	1,735.0				1,685.9
Noncurrent Liabilities	8,944.5				8,749.3
Equity	5,609.9		$ 5,580.0	$ 5,512.7	5,276.7		$ 5,226.3	$ 5,133.1	$ 5,086.9	$ 4,975.4
Total Liabilities and Equity	16,289.4				15,711.9
Sabine Mining Co [Member] | Variable Interest Entities [Member] | Southwestern Electric Power Co [Member]
ASSETS
Current Assets	6.6				4.2
Net Property, Plant and Equipment	0.0				0.0
TOTAL OTHER NONCURRENT ASSETS	120.1				150.7
Total Assets	126.7				154.9
LIABILITIES AND EQUITY
Current Liabilities	23.9				19.9
Noncurrent Liabilities	102.5				134.8
Equity	0.3				0.2
Total Liabilities and Equity	126.7				154.9
DCC Fuel [Member] | Variable Interest Entities [Member] | Indiana Michigan Power Co [Member]
ASSETS
Current Assets	93.6				81.9
Net Property, Plant and Equipment	160.5				153.8
TOTAL OTHER NONCURRENT ASSETS	76.0				81.7
Total Assets	330.1				317.4
LIABILITIES AND EQUITY
Current Liabilities	93.4				81.7
Noncurrent Liabilities	236.7				235.7
Equity	0.0				0.0
Total Liabilities and Equity	330.1				317.4
AEP Texas Central Transition Funding Co [Member] | AEP Texas Inc. [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	2.0				8.0
AEP Texas Central Transition Funding Co [Member] | Variable Interest Entities [Member] | AEP Texas Inc. [Member]
ASSETS
Current Assets	44.5				25.5
Net Property, Plant and Equipment	0.0				0.0
TOTAL OTHER NONCURRENT ASSETS	19.6	[1]			71.4	[2]
Total Assets	64.1				96.9
LIABILITIES AND EQUITY
Current Liabilities	43.2				75.5
Noncurrent Liabilities	16.3				17.0
Equity	4.6				4.4
Total Liabilities and Equity	64.1				96.9
Restoration Funding [Member] | AEP Texas Inc. [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	5.0				6.0
Restoration Funding [Member] | Variable Interest Entities [Member] | AEP Texas Inc. [Member]
ASSETS
Current Assets	15.9				27.5
Net Property, Plant and Equipment	0.0				0.0
TOTAL OTHER NONCURRENT ASSETS	127.8	[3]			145.6	[4]
Total Assets	143.7				173.1
LIABILITIES AND EQUITY
Current Liabilities	29.9				36.8
Noncurrent Liabilities	112.5				135.1
Equity	1.3				1.2
Total Liabilities and Equity	143.7				173.1
Appalachian Consumer Rate Relief Funding [Member] | Appalachian Power Co [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	1.0				2.0
Appalachian Consumer Rate Relief Funding [Member] | Variable Interest Entities [Member] | Appalachian Power Co [Member]
ASSETS
Current Assets	5.6				13.3
Net Property, Plant and Equipment	0.0				0.0
TOTAL OTHER NONCURRENT ASSETS	117.0	[5]			138.2	[6]
Total Assets	122.6				151.5
LIABILITIES AND EQUITY
Current Liabilities	29.4				29.9
Noncurrent Liabilities	91.3				119.7
Equity	1.9				1.9
Total Liabilities and Equity	122.6				151.5
AEP Credit, Inc. [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	1,287.0				1,208.8
Net Property, Plant and Equipment	0.0				0.0
TOTAL OTHER NONCURRENT ASSETS	11.0				9.6
Total Assets	1,298.0				1,218.4
LIABILITIES AND EQUITY
Current Liabilities	1,230.9				1,155.0
Noncurrent Liabilities	1.0				0.9
Equity	66.1				62.5
Total Liabilities and Equity	1,298.0				1,218.4
Protected Cell Of Energy Insurance Services, Inc. [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	232.1				205.3
Net Property, Plant and Equipment	0.0				0.0
TOTAL OTHER NONCURRENT ASSETS	0.0				0.0
Total Assets	232.1				205.3
LIABILITIES AND EQUITY
Current Liabilities	58.8				49.2
Noncurrent Liabilities	106.5				91.7
Equity	66.8				64.4
Total Liabilities and Equity	232.1				205.3
Transource Energy [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	35.0				36.9
Net Property, Plant and Equipment	581.0				533.4
TOTAL OTHER NONCURRENT ASSETS	4.1				5.1
Total Assets	620.1				575.4
LIABILITIES AND EQUITY
Current Liabilities	26.4				45.3
Noncurrent Liabilities	289.4				241.5
Equity	304.3				288.6
Total Liabilities and Equity	$ 620.1				$ 575.4

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

[2] Includes an intercompany item eliminated in consolidation of $8 million.

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

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

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

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