Variable Interest Entities (Details) - USD ($) $ in Millions	Mar. 31, 2024		Dec. 31, 2023		Mar. 31, 2023	Dec. 31, 2022
ASSETS
Current Assets	$ 5,849.6		$ 6,082.1
Net Property, Plant and Equipment	77,796.0		76,693.4
Other Noncurrent Assets	14,099.0		13,908.5
Total Assets	97,744.6		96,684.0
LIABILITIES AND EQUITY
Current Liabilities	10,906.6		11,583.6
Noncurrent Liabilities	60,942.7		59,772.0
Equity	25,843.7		25,285.9		$ 23,967.8	$ 24,122.4
Total Liabilities and Equity	97,744.6		96,684.0
Southwestern Electric Power Co [Member]
ASSETS
Current Assets	548.1		541.3
Net Property, Plant and Equipment	8,666.7		8,558.4
Other Noncurrent Assets	1,533.2		1,457.9
Total Assets	10,748.0		10,557.6
LIABILITIES AND EQUITY
Current Liabilities	851.3		686.9
Noncurrent Liabilities	5,968.3		6,100.3
Equity	3,928.4		3,770.4		3,765.2	3,674.8
Total Liabilities and Equity	10,748.0		10,557.6
Indiana Michigan Power Co [Member]
ASSETS
Current Assets	480.0		528.0
Net Property, Plant and Equipment	7,651.2		7,629.0
Other Noncurrent Assets	4,980.3		4,651.0
Total Assets	13,111.5		12,808.0
LIABILITIES AND EQUITY
Current Liabilities	783.3		830.2
Noncurrent Liabilities	9,080.4		8,837.6
Equity	3,247.8		3,140.2		3,077.3	3,008.3
Total Liabilities and Equity	13,111.5		12,808.0
AEP Texas Inc. [Member]
ASSETS
Current Assets	525.1		520.1
Net Property, Plant and Equipment	13,079.4		12,774.0
Other Noncurrent Assets	763.0		696.6
Total Assets	14,367.5		13,990.7
LIABILITIES AND EQUITY
Current Liabilities	1,041.9		749.4
Noncurrent Liabilities	8,445.9		8,445.2
Equity	4,879.7		4,796.1		4,051.3	3,904.3
Total Liabilities and Equity	14,367.5		13,990.7
Appalachian Power Co [Member]
ASSETS
Current Assets	1,019.8		1,059.0
Net Property, Plant and Equipment	13,052.9		12,931.5
Other Noncurrent Assets	1,679.7		1,721.4
Total Assets	15,752.4		15,711.9
LIABILITIES AND EQUITY
Current Liabilities	1,023.3		1,685.9
Noncurrent Liabilities	9,216.4		8,749.3
Equity	5,512.7		5,276.7		$ 5,086.9	$ 4,975.4
Total Liabilities and Equity	15,752.4		15,711.9
Sabine Mining Co [Member] | Variable Interest Entities [Member] | Southwestern Electric Power Co [Member]
ASSETS
Current Assets	5.1		4.2
Net Property, Plant and Equipment	0.0		0.0
Other Noncurrent Assets	140.1		150.7
Total Assets	145.2		154.9
LIABILITIES AND EQUITY
Current Liabilities	22.8		19.9
Noncurrent Liabilities	122.1		134.8
Equity	0.3		0.2
Total Liabilities and Equity	145.2		154.9
DCC Fuel [Member] | Variable Interest Entities [Member] | Indiana Michigan Power Co [Member]
ASSETS
Current Assets	75.3		81.9
Net Property, Plant and Equipment	129.5		153.8
Other Noncurrent Assets	63.5		81.7
Total Assets	268.3		317.4
LIABILITIES AND EQUITY
Current Liabilities	75.1		81.7
Noncurrent Liabilities	193.2		235.7
Equity	0.0		0.0
Total Liabilities and Equity	268.3		317.4
AEP Texas Central Transition Funding Co [Member] | AEP Texas Inc. [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	6.0		8.0
AEP Texas Central Transition Funding Co [Member] | Variable Interest Entities [Member] | AEP Texas Inc. [Member]
ASSETS
Current Assets	40.1		25.5
Net Property, Plant and Equipment	0.0		0.0
Other Noncurrent Assets	55.3	[1]	71.4	[2]
Total Assets	95.4		96.9
LIABILITIES AND EQUITY
Current Liabilities	76.3		75.5
Noncurrent Liabilities	14.7		17.0
Equity	4.4		4.4
Total Liabilities and Equity	95.4		96.9
Restoration Funding [Member] | AEP Texas Inc. [Member] | Other Noncurrent Assets [Member]
LIABILITIES AND EQUITY
Unearned Revenue	6.0		6.0
Restoration Funding [Member] | Variable Interest Entities [Member] | AEP Texas Inc. [Member]
ASSETS
Current Assets	20.4		27.5
Net Property, Plant and Equipment	0.0		0.0
Other Noncurrent Assets	139.7	[3]	145.6	[4]
Total Assets	160.1		173.1
LIABILITIES AND EQUITY
Current Liabilities	36.4		36.8
Noncurrent Liabilities	122.4		135.1
Equity	1.3		1.2
Total Liabilities and Equity	160.1		173.1
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	6.3		13.3
Net Property, Plant and Equipment	0.0		0.0
Other Noncurrent Assets	130.3	[5]	138.2	[6]
Total Assets	136.6		151.5
LIABILITIES AND EQUITY
Current Liabilities	29.0		29.9
Noncurrent Liabilities	105.7		119.7
Equity	1.9		1.9
Total Liabilities and Equity	136.6		151.5
AEP Credit, Inc. [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	1,165.3		1,208.8
Net Property, Plant and Equipment	0.0		0.0
Other Noncurrent Assets	10.2		9.6
Total Assets	1,175.5		1,218.4
LIABILITIES AND EQUITY
Current Liabilities	1,113.7		1,155.0
Noncurrent Liabilities	1.0		0.9
Equity	60.8		62.5
Total Liabilities and Equity	1,175.5		1,218.4
Protected Cell Of Energy Insurance Services, Inc. [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	211.6		205.3
Net Property, Plant and Equipment	0.0		0.0
Other Noncurrent Assets	0.0		0.0
Total Assets	211.6		205.3
LIABILITIES AND EQUITY
Current Liabilities	52.3		49.2
Noncurrent Liabilities	90.8		91.7
Equity	68.5		64.4
Total Liabilities and Equity	211.6		205.3
Transource Energy [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets	31.7		36.9
Net Property, Plant and Equipment	536.9		533.4
Other Noncurrent Assets	9.3		5.1
Total Assets	577.9		575.4
LIABILITIES AND EQUITY
Current Liabilities	22.5		45.3
Noncurrent Liabilities	258.8		241.5
Equity	296.6		288.6
Total Liabilities and Equity	$ 577.9		$ 575.4

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

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

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

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

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

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