Property, Plant and Equipment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		$ 23,133.9		$ 22,762.4
Property, Plant and Equipment, Transmission		27,886.7		24,808.6
Property, Plant and Equipment, Distribution		23,972.1		22,443.4
Property, Plant and Equipment, Other		5,294.6		4,811.5
Property, Plant and Equipment, Construction Work in Progress		4,025.7		4,319.8
Accumulated Depreciation		20,411.4		19,007.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		63,901.6		60,138.1
Asset Retirement Obligations (ARO)
Beginning Balance	[1],[2],[3],[4]	2,418.9		2,355.5
Accretion Expense	[1],[2],[3],[4]	102.4		102.5
Liabilities Incurred	[1],[2],[3],[4]	0.3		12.0
Liabilities Settled	[1],[2],[3],[4]	(188.0)		(118.1)
Revisions in Cash Flow Estimates	[1],[2],[3],[4],[5]	183.1		67.0
Ending Balance	[1],[2],[3],[4]	2,516.7		2,418.9	$ 2,355.5
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		148.1		168.4	132.5
Allowance for Borrowed Funds Used During Construction		66.0		88.7	73.6
Jointly-owned Electric Facilities
Utility Plant in Service		2,916.7		3,019.3
Construction Work in Progress		14.1		19.1
Accumulated Depreciation		1,109.7		1,051.9
Asset Impairments and Other Related Charges		0.0		156.4	70.6
Property, Plant and Equipment (Textuals)
Asset Retirement Obligations (ARO) Liability for Nuclear Decommissioning of the Cook Plant		1,800.0		1,730.0
AEP Texas Inc. [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		0.0		351.7
Property, Plant and Equipment, Transmission		5,279.6		4,466.5
Property, Plant and Equipment, Distribution		4,580.8		4,215.2
Property, Plant and Equipment, Other		868.4		805.9
Property, Plant and Equipment, Construction Work in Progress		614.1		763.9
Accumulated Depreciation		1,529.3		1,758.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		9,813.6		8,845.1
Asset Retirement Obligations (ARO)
Beginning Balance	[2],[3]	29.1		27.9
Accretion Expense	[2],[3]	0.8		1.3
Liabilities Incurred	[2],[3]	0.0		0.0
Liabilities Settled	[2],[3]	(8.5)		(0.2)
Revisions in Cash Flow Estimates	[2],[3],[5]	(16.8)		0.1
Ending Balance	[2],[3]	4.6		29.1	27.9
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		19.4		15.2	20.0
Allowance for Borrowed Funds Used During Construction		$ 12.5		20.0	18.4
Jointly-owned Electric Facilities
Percent of Ownership		54.69%
Asset Impairments and Other Related Charges		$ 0.0		32.5	0.0
AEP Transmission Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Transmission		9,593.5		8,137.9
Property, Plant and Equipment, Other		329.5		269.6
Property, Plant and Equipment, Construction Work in Progress		1,422.6		1,485.7
Accumulated Depreciation		572.8		402.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		10,772.8		9,490.9
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		74.0		84.3	70.6
Allowance for Borrowed Funds Used During Construction		25.5		32.2	26.1
Appalachian Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		6,633.7		6,563.7
Property, Plant and Equipment, Transmission		3,900.5		3,584.1
Property, Plant and Equipment, Distribution		4,464.3		4,201.7
Property, Plant and Equipment, Other		627.2		571.3
Property, Plant and Equipment, Construction Work in Progress		484.6		593.4
Accumulated Depreciation		4,716.2		4,432.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		11,394.1		11,081.9
Asset Retirement Obligations (ARO)
Beginning Balance	[2],[3]	111.1		116.1
Accretion Expense	[2],[3]	8.9		5.9
Liabilities Incurred	[2],[3]	0.0		0.0
Liabilities Settled	[2],[3]	(7.8)		(17.6)
Revisions in Cash Flow Estimates	[2],[3],[5]	200.9		6.7
Ending Balance	[2],[3]	313.1		111.1	116.1
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		14.6		16.6	13.2
Allowance for Borrowed Funds Used During Construction		7.9		9.3	8.4
Jointly-owned Electric Facilities
Asset Impairments and Other Related Charges		0.0		92.9	0.0
Indiana Michigan Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		5,264.7		5,099.7
Property, Plant and Equipment, Transmission		1,696.4		1,641.8
Property, Plant and Equipment, Distribution		2,594.6		2,437.6
Property, Plant and Equipment, Other		686.7		632.6
Property, Plant and Equipment, Construction Work in Progress		362.4		382.3
Accumulated Depreciation		3,552.5		3,294.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		7,052.3		6,899.7
Asset Retirement Obligations (ARO)
Beginning Balance	[2],[3],[4]	1,748.6		1,681.3
Accretion Expense	[2],[3],[4]	70.2		67.4
Liabilities Incurred	[2],[3],[4]	0.1		0.0
Liabilities Settled	[2],[3],[4]	(0.2)		(0.2)
Revisions in Cash Flow Estimates	[2],[3],[4],[5]	(4.9)		0.1
Ending Balance	[2],[3],[4]	1,813.8		1,748.6	1,681.3
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		11.5		19.4	11.9
Allowance for Borrowed Funds Used During Construction		5.7		8.9	7.4
Property, Plant and Equipment (Textuals)
Asset Retirement Obligations (ARO) Liability for Nuclear Decommissioning of the Cook Plant		1,800.0		1,730.0
Fair Value of Legally Restricted Assets		2,980.0		2,650.0
Ohio Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Transmission		2,831.9		2,686.3
Property, Plant and Equipment, Distribution		5,708.3		5,323.5
Property, Plant and Equipment, Other		899.6		765.8
Property, Plant and Equipment, Construction Work in Progress		362.3		394.4
Accumulated Depreciation		2,350.0		2,263.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		7,452.1		6,907.0
Asset Retirement Obligations (ARO)
Beginning Balance	[2]	1.8		1.8
Accretion Expense	[2]	0.1		0.1
Liabilities Incurred	[2]	0.0		0.0
Liabilities Settled	[2]	0.0		(0.3)
Revisions in Cash Flow Estimates	[2],[5]	0.0		0.2
Ending Balance	[2]	1.9		1.8	1.8
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		12.5		18.2	9.8
Allowance for Borrowed Funds Used During Construction		6.2		6.7	5.8
Public Service Co Of Oklahoma [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		1,480.7		1,574.6
Property, Plant and Equipment, Transmission		1,069.9		948.5
Property, Plant and Equipment, Distribution		2,853.0		2,684.8
Property, Plant and Equipment, Other		393.3		342.1
Property, Plant and Equipment, Construction Work in Progress		128.7		133.4
Accumulated Depreciation		1,605.6		1,580.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		4,320.0		4,103.3
Asset Retirement Obligations (ARO)
Beginning Balance	[2],[3]	52.2		46.9
Accretion Expense	[2],[3]	3.1		3.1
Liabilities Incurred	[2],[3]	0.0		0.0
Liabilities Settled	[2],[3]	(3.1)		(0.4)
Revisions in Cash Flow Estimates	[2],[3],[5]	(4.8)		2.6
Ending Balance	[2],[3]	47.4		52.2	46.9
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		4.0		2.7	0.4
Allowance for Borrowed Funds Used During Construction		2.0		1.9	0.9
Southwestern Electric Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		4,681.4		4,691.4
Property, Plant and Equipment, Transmission		2,165.7		2,056.5
Property, Plant and Equipment, Distribution		2,382.5		2,270.7
Property, Plant and Equipment, Other		788.8		733.4
Property, Plant and Equipment, Construction Work in Progress		228.3		216.9
Accumulated Depreciation		3,158.5		2,873.7
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		7,088.2		7,095.2
Asset Retirement Obligations (ARO)
Beginning Balance	[1],[2],[3]	212.2		206.8
Accretion Expense	[1],[2],[3]	10.7		10.3
Liabilities Incurred	[1],[2],[3]	0.0		0.0
Liabilities Settled	[1],[2],[3]	(10.9)		(11.8)
Revisions in Cash Flow Estimates	[1],[2],[3],[5]	10.1		6.9
Ending Balance	[1],[2],[3]	222.1		212.2	206.8
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalization
Allowance for Equity Funds Used During Construction		7.7		6.8	6.0
Allowance for Borrowed Funds Used During Construction		3.9		4.0	$ 4.8
Jointly-owned Electric Facilities
Utility Plant in Service		2,916.7		2,912.7
Construction Work in Progress		14.1		19.0
Accumulated Depreciation		1,109.7		$ 960.2
Southwestern Electric Power Co [Member] | Ash Pond [Member]
Asset Retirement Obligations (ARO)
Revisions in Cash Flow Estimates		$ (18.0)
Dolet Hills Generating Station (Unit No. 1) [Member] | Public Utilities, Inventory, Lignite [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[6]	40.20%		40.20%
Utility Plant in Service	[6]	$ 342.4		$ 337.3
Construction Work in Progress	[6]	4.6		6.2
Accumulated Depreciation	[6]	$ 295.4		$ 216.5
Dolet Hills Generating Station (Unit No. 1) [Member] | Southwestern Electric Power Co [Member] | Public Utilities, Inventory, Lignite [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[6]	40.20%		40.20%
Utility Plant in Service	[6]	$ 342.4		$ 337.3
Construction Work in Progress	[6]	4.6		6.2
Accumulated Depreciation	[6]	$ 295.4		$ 216.5
Flint Creek Generating Station (Unit No. 1) [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[7]	50.00%		50.00%
Utility Plant in Service	[7]	$ 377.2		$ 374.3
Construction Work in Progress	[7]	3.0		3.4
Accumulated Depreciation	[7]	$ 116.0		$ 101.1
Flint Creek Generating Station (Unit No. 1) [Member] | Southwestern Electric Power Co [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[7]	50.00%		50.00%
Utility Plant in Service	[7]	$ 377.2		$ 374.3
Construction Work in Progress	[7]	3.0		3.4
Accumulated Depreciation	[7]	$ 116.0		$ 101.1
Pirkey Generating Station (Unit No. 1) [Member] | Public Utilities, Inventory, Lignite [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[7]	85.90%		85.90%
Utility Plant in Service	[7]	$ 602.8		$ 607.8
Construction Work in Progress	[7]	3.7		7.7
Accumulated Depreciation	[7]	$ 441.0		$ 416.8
Pirkey Generating Station (Unit No. 1) [Member] | Southwestern Electric Power Co [Member] | Public Utilities, Inventory, Lignite [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[7]	85.90%		85.90%
Utility Plant in Service	[7]	$ 602.8		$ 607.8
Construction Work in Progress	[7]	3.7		7.7
Accumulated Depreciation	[7]	$ 441.0		$ 416.8
Oklaunion Generating Station (Unit No. 1) [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[8],[9]	70.30%		70.30%
Utility Plant in Service	[8],[9]	$ 0.0		$ 106.6
Construction Work in Progress	[8],[9]	0.0		0.1
Accumulated Depreciation	[8],[9]	$ 0.0		$ 91.7
Oklaunion Generating Station (Unit No. 1) [Member] | AEP Texas Inc. [Member]
Jointly-owned Electric Facilities
Percent of Ownership		54.70%
Oklaunion Generating Station (Unit No. 1) [Member] | AEP Texas Inc. [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[8],[9]	54.70%		54.70%
Utility Plant in Service	[8],[9]	$ 0.0		$ 351.7
Construction Work in Progress	[8],[9]	0.0		0.0
Accumulated Depreciation	[8],[9]	$ 0.0		$ 291.9
Oklaunion Generating Station (Unit No. 1) [Member] | Public Service Co Of Oklahoma [Member]
Jointly-owned Electric Facilities
Percent of Ownership		15.60%
Oklaunion Generating Station (Unit No. 1) [Member] | Public Service Co Of Oklahoma [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[8],[9]	15.60%		15.60%
Utility Plant in Service	[8],[9]	$ 0.0		$ 106.6
Construction Work in Progress	[8],[9]	0.0		0.1
Accumulated Depreciation	[8],[9]	$ 0.0		$ 91.7
Turk Generating Plant [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership		73.30%	[7]	73.30%
Utility Plant in Service	[7]	$ 1,594.3		$ 1,593.3
Construction Work in Progress	[7]	2.8		1.7
Accumulated Depreciation	[7]	$ 257.3		$ 225.8
Turk Generating Plant [Member] | Southwestern Electric Power Co [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[7]	73.30%		73.30%
Utility Plant in Service	[7]	$ 1,594.3		$ 1,593.3
Construction Work in Progress	[7]	2.8		1.7
Accumulated Depreciation	[7]	$ 257.3		$ 225.8
Rockport Generating Plant (Unit No. 1) [Member] | Indiana Michigan Power Co [Member]
Jointly-owned Electric Facilities
Percent of Ownership		50.00%
Rockport Generating Plant (Unit No. 1) [Member] | Indiana Michigan Power Co [Member] | Coal [Member]
Jointly-owned Electric Facilities
Percent of Ownership	[10],[11],[12]	50.00%		50.00%
Utility Plant in Service	[10],[11],[12]	$ 1,228.5		$ 1,114.2
Construction Work in Progress	[10],[11],[12]	19.6		105.5
Accumulated Depreciation	[10],[11],[12]	$ 677.3		586.2
Rockport Generating Plant (Unit No. 1) [Member] | AEP Generating Co [Member]
Jointly-owned Electric Facilities
Percent of Ownership		50.00%
Rockport Generating Plant (Unit No. 2) [Member] | AEP Generating Co [Member]
Jointly-owned Electric Facilities
Percentage Interest in Lease		50.00%
Regulated Operation [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation	[13]	$ 21,587.8		21,323.5
Property, Plant and Equipment, Transmission		27,841.5		24,763.4
Property, Plant and Equipment, Distribution		23,972.1		22,440.8
Property, Plant and Equipment, Other		4,852.4		4,369.6
Property, Plant and Equipment, Construction Work in Progress	[13]	3,815.0		4,261.2
Accumulated Depreciation		20,094.2		18,778.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 61,974.6		$ 58,380.4
Regulated Operation [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		132 years		132 years	132 years
Depreciable Life Ranges - Transmission		75 years		81 years	81 years
Depreciable Life Ranges - Distribution		78 years		78 years	78 years
Depreciable Life Ranges - Other		75 years		75 years	75 years
Regulated Operation [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		20 years		20 years	20 years
Depreciable Life Ranges - Transmission		15 years		15 years	15 years
Depreciable Life Ranges - Distribution		7 years		7 years	7 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | Generation [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		6.30%		5.50%	4.00%
Regulated Operation [Member] | Generation [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.70%		2.50%	2.40%
Regulated Operation [Member] | Transmission [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.60%		2.60%	2.70%
Regulated Operation [Member] | Transmission [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.00%		1.80%	1.60%
Regulated Operation [Member] | Distribution [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.70%		3.70%	3.60%
Regulated Operation [Member] | Distribution [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.70%		2.70%	2.70%
Regulated Operation [Member] | Other Property Class [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		11.30%		9.50%	9.80%
Regulated Operation [Member] | Other Property Class [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.80%		2.60%	2.30%
Regulated Operation [Member] | AEP Texas Inc. [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		$ 0.0		$ 0.0
Property, Plant and Equipment, Transmission		5,279.6		4,466.5
Property, Plant and Equipment, Distribution		4,580.8		4,215.2
Property, Plant and Equipment, Other		866.0		803.4
Property, Plant and Equipment, Construction Work in Progress		614.1		763.9
Accumulated Depreciation		1,528.1		1,465.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 9,812.4		$ 8,784.0
Regulated Operation [Member] | AEP Texas Inc. [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Transmission		75 years		81 years	81 years
Depreciable Life Ranges - Distribution		70 years		70 years	70 years
Depreciable Life Ranges - Other		50 years		50 years	50 years
Regulated Operation [Member] | AEP Texas Inc. [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Transmission		50 years		45 years	45 years
Depreciable Life Ranges - Distribution		7 years		7 years	7 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | AEP Texas Inc. [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.00%		1.80%	1.70%
Regulated Operation [Member] | AEP Texas Inc. [Member] | Distribution [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.10%		3.50%	3.60%
Regulated Operation [Member] | AEP Texas Inc. [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		6.10%		6.30%	6.00%
Regulated Operation [Member] | AEP Transmission Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		$ 0.0		$ 0.0
Property, Plant and Equipment, Transmission		9,593.5		8,137.9
Property, Plant and Equipment, Distribution		0.0		0.0
Property, Plant and Equipment, Other		328.8		268.2
Property, Plant and Equipment, Construction Work in Progress		1,422.6		1,485.7
Accumulated Depreciation		572.8		402.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 10,772.1		$ 9,489.5
Regulated Operation [Member] | AEP Transmission Co [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Transmission		75 years		75 years	75 years
Depreciable Life Ranges - Other		64 years		64 years	64 years
Regulated Operation [Member] | AEP Transmission Co [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Transmission		24 years		24 years	20 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | AEP Transmission Co [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.40%		2.00%	1.90%
Regulated Operation [Member] | AEP Transmission Co [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		6.30%		5.80%	5.60%
Regulated Operation [Member] | Appalachian Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		$ 6,633.7		$ 6,563.7
Property, Plant and Equipment, Transmission		3,900.5		3,584.1
Property, Plant and Equipment, Distribution		4,464.3		4,201.7
Property, Plant and Equipment, Other		598.0		542.0
Property, Plant and Equipment, Construction Work in Progress		484.6		593.4
Accumulated Depreciation		4,711.0		4,425.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 11,370.1		$ 11,059.3
Regulated Operation [Member] | Appalachian Power Co [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		118 years		118 years	112 years
Depreciable Life Ranges - Transmission		75 years		71 years	68 years
Depreciable Life Ranges - Distribution		57 years		57 years	57 years
Depreciable Life Ranges - Other		55 years		55 years	55 years
Regulated Operation [Member] | Appalachian Power Co [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		35 years		35 years	35 years
Depreciable Life Ranges - Transmission		15 years		15 years	15 years
Depreciable Life Ranges - Distribution		12 years		12 years	10 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | Appalachian Power Co [Member] | Generation [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.30%		3.20%	3.10%
Regulated Operation [Member] | Appalachian Power Co [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.20%		1.80%	1.60%
Regulated Operation [Member] | Appalachian Power Co [Member] | Distribution [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.70%		3.70%	3.60%
Regulated Operation [Member] | Appalachian Power Co [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		7.80%		7.20%	7.40%
Regulated Operation [Member] | Indiana Michigan Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		$ 5,264.7		$ 5,099.7
Property, Plant and Equipment, Transmission		1,696.4		1,641.8
Property, Plant and Equipment, Distribution		2,594.6		2,437.6
Property, Plant and Equipment, Other		644.6		590.9
Property, Plant and Equipment, Construction Work in Progress		362.4		382.3
Accumulated Depreciation		3,538.6		3,281.4
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 7,024.1		$ 6,870.9
Regulated Operation [Member] | Indiana Michigan Power Co [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		132 years		132 years	132 years
Depreciable Life Ranges - Transmission		70 years		73 years	73 years
Depreciable Life Ranges - Distribution		71 years		75 years	75 years
Depreciable Life Ranges - Other		51 years		50 years	50 years
Regulated Operation [Member] | Indiana Michigan Power Co [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		20 years		20 years	20 years
Depreciable Life Ranges - Transmission		45 years		50 years	50 years
Depreciable Life Ranges - Distribution		14 years		9 years	9 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | Indiana Michigan Power Co [Member] | Generation [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		4.60%		4.00%	3.40%
Regulated Operation [Member] | Indiana Michigan Power Co [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.30%		1.90%	1.80%
Regulated Operation [Member] | Indiana Michigan Power Co [Member] | Distribution [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.40%		3.40%	3.10%
Regulated Operation [Member] | Indiana Michigan Power Co [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		10.20%		9.40%	8.90%
Regulated Operation [Member] | Ohio Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		$ 0.0		$ 0.0
Property, Plant and Equipment, Transmission		2,831.9		2,686.3
Property, Plant and Equipment, Distribution		5,708.3		5,323.5
Property, Plant and Equipment, Other		888.5		754.7
Property, Plant and Equipment, Construction Work in Progress		362.3		394.4
Accumulated Depreciation		2,348.8		2,261.7
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 7,442.2		$ 6,897.2
Regulated Operation [Member] | Ohio Power Co [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Transmission		60 years		60 years	60 years
Depreciable Life Ranges - Distribution		65 years		65 years	65 years
Depreciable Life Ranges - Other		50 years		50 years	50 years
Regulated Operation [Member] | Ohio Power Co [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Transmission		39 years		39 years	39 years
Depreciable Life Ranges - Distribution		14 years		14 years	14 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | Ohio Power Co [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.30%		2.30%	2.30%
Regulated Operation [Member] | Ohio Power Co [Member] | Distribution [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.10%		3.10%	3.00%
Regulated Operation [Member] | Ohio Power Co [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		5.00%		4.90%	6.30%
Regulated Operation [Member] | Public Service Co Of Oklahoma [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation		$ 1,480.7		$ 1,574.6
Property, Plant and Equipment, Transmission		1,069.9		948.5
Property, Plant and Equipment, Distribution		2,853.0		2,684.8
Property, Plant and Equipment, Other		388.1		337.2
Property, Plant and Equipment, Construction Work in Progress		128.7		133.4
Accumulated Depreciation		1,607.3		1,579.9
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 4,313.1		$ 4,098.6
Regulated Operation [Member] | Public Service Co Of Oklahoma [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		75 years		75 years	75 years
Depreciable Life Ranges - Transmission		75 years		75 years	75 years
Depreciable Life Ranges - Distribution		78 years		78 years	78 years
Depreciable Life Ranges - Other		64 years		64 years	64 years
Regulated Operation [Member] | Public Service Co Of Oklahoma [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		35 years		35 years	35 years
Depreciable Life Ranges - Transmission		45 years		45 years	45 years
Depreciable Life Ranges - Distribution		15 years		15 years	15 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | Public Service Co Of Oklahoma [Member] | Generation [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.10%		2.90%	2.90%
Regulated Operation [Member] | Public Service Co Of Oklahoma [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.20%		2.40%	2.30%
Regulated Operation [Member] | Public Service Co Of Oklahoma [Member] | Distribution [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.90%		2.90%	2.90%
Regulated Operation [Member] | Public Service Co Of Oklahoma [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		5.70%		5.60%	6.30%
Regulated Operation [Member] | Southwestern Electric Power Co [Member]
Depreciation, Depletion and Amortization
Property, Plant and Equipment, Generation	[13]	$ 4,681.4		$ 4,691.4
Property, Plant and Equipment, Transmission		2,165.7		2,056.5
Property, Plant and Equipment, Distribution		2,382.5		2,270.7
Property, Plant and Equipment, Other		564.5		520.6
Property, Plant and Equipment, Construction Work in Progress	[13]	228.3		210.1
Accumulated Depreciation		3,032.0		2,766.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 6,990.4		$ 6,983.1
Regulated Operation [Member] | Southwestern Electric Power Co [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		65 years		70 years	70 years
Depreciable Life Ranges - Transmission		73 years		73 years	73 years
Depreciable Life Ranges - Distribution		67 years		70 years	70 years
Depreciable Life Ranges - Other		52 years		55 years	55 years
Regulated Operation [Member] | Southwestern Electric Power Co [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		35 years		40 years	40 years
Depreciable Life Ranges - Transmission		47 years		50 years	50 years
Depreciable Life Ranges - Distribution		15 years		25 years	25 years
Depreciable Life Ranges - Other		5 years		5 years	5 years
Regulated Operation [Member] | Southwestern Electric Power Co [Member] | Generation [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.70%		2.50%	2.40%
Regulated Operation [Member] | Southwestern Electric Power Co [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.30%		2.40%	2.20%
Regulated Operation [Member] | Southwestern Electric Power Co [Member] | Distribution [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.70%		2.70%	2.70%
Regulated Operation [Member] | Southwestern Electric Power Co [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		8.50%		7.60%	8.00%
Unregulated Operation [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 1,927.0		$ 1,757.7
Depreciable Life Ranges - Transmission					40 years
Depreciable Life Ranges - Distribution				40 years	40 years
Unregulated Operation [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		59 years		59 years	59 years
Depreciable Life Ranges - Transmission		40 years		40 years
Depreciable Life Ranges - Other	[14]	50 years		50 years	50 years
Unregulated Operation [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Generation		15 years		15 years	15 years
Depreciable Life Ranges - Transmission		30 years		30 years
Depreciable Life Ranges - Other	[14]	5 years		5 years	5 years
Unregulated Operation [Member] | Generation [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		4.00%		21.20%	22.30%
Unregulated Operation [Member] | Generation [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		3.60%		3.20%	3.40%
Unregulated Operation [Member] | Transmission [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		2.50%		2.50%	2.40%
Unregulated Operation [Member] | Distribution [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate				2.30%	2.30%
Unregulated Operation [Member] | Other Property Class [Member]
Depreciation, Depletion and Amortization
Annual Composite Depreciation Rate		16.10%		17.60%	16.30%
Unregulated Operation [Member] | AEP Texas Inc. [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 1.2		$ 61.1
Unregulated Operation [Member] | AEP Transmission Co [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		0.7		1.4
Unregulated Operation [Member] | Appalachian Power Co [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		24.0		22.6
Unregulated Operation [Member] | Indiana Michigan Power Co [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		28.2		28.8
Unregulated Operation [Member] | Ohio Power Co [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		9.9		9.8
Unregulated Operation [Member] | Public Service Co Of Oklahoma [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6.9		4.7
Unregulated Operation [Member] | Southwestern Electric Power Co [Member]
Depreciation, Depletion and Amortization
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		$ 97.8		112.1
Unregulated Operation [Member] | Southwestern Electric Power Co [Member] | Maximum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Other		20 years
Unregulated Operation [Member] | Southwestern Electric Power Co [Member] | Minimum [Member]
Depreciation, Depletion and Amortization
Depreciable Life Ranges - Other		3 years
Oklaunion Generating Station [Member] | AEP Texas Inc. [Member]
Asset Retirement Obligations (ARO)
Revisions in Cash Flow Estimates		$ (17.0)
Oklaunion Generating Station [Member] | Public Service Co Of Oklahoma [Member]
Asset Retirement Obligations (ARO)
Revisions in Cash Flow Estimates		(5.0)
Dolet Hills Power Station [Member] | Southwestern Electric Power Co [Member]
Asset Retirement Obligations (ARO)
Revisions in Cash Flow Estimates		21.0
Glen Lyn Station [Member] | Appalachian Power Co [Member]
Asset Retirement Obligations (ARO)
Revisions in Cash Flow Estimates		199.0
Generation and Marketing [Member]
Depreciation, Depletion and Amortization
Accumulated Depreciation		166.1		99.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		1,744.1		1,551.8
Jointly-owned Electric Facilities
Asset Impairments and Other Related Charges				$ 31.0	$ 47.7
Generation and Marketing [Member] | Conesville Generating Station [Member]
Asset Retirement Obligations (ARO)
Liabilities Settled		$ (106.0)

[1] Includes ARO related to Sabine and DHLC.

[2] Includes ARO related to asbestos removal.

[3] Includes ARO related to ash disposal facilities.

[4] Includes ARO related to nuclear decommissioning costs for the Cook Plant of $1.80 billion and $1.73 billion as of December 31, 2020 and 2019, respectively.

[5] Unless discussed above, primarily related to ash ponds, landfills and mine reclamation, generally due to changes in estimated closure area, volumes and/or unit costs.

[6] Operated by CLECO, a nonaffiliated company.

[7] Operated by SWEPCo.

[8] Oklaunion Power Station was retired in September 2020 and sold to a nonaffiliated third-party in October 2020. See the “Dispositions” section of Note 7 for additional information.

[9] Operated by PSO, which owned 15.6%. Also was jointly-owned (54.7%) by AEP Texas and various nonaffiliated companies.

[10] AEGCo owns 50% of Unit 1 with I&M and 50% of capital additions for Unit 2.

[11] Amounts include I&M’s 50% ownership of both Unit 1 and capital additions for Unit 2. Unit 2 is subject to an operating lease with a nonaffiliated company. See the “Rockport Lease” section of Note 13 for additional information.

[12] Operated by I&M.

[13] AEP and SWEPCo’s regulated generation and regulated CWIP include amounts related to SWEPCo’s Arkansas jurisdictional share of the Turk Plant.

[14] SWEPCo’s nonregulated property, plant and equipment is depreciated using the straight-line method over a range of 3 to 20 years.NA Not applicable.