Derivatives and Hedging (Details) gal in Millions, MWh in Millions, MMBTU in Millions		3 Months Ended			6 Months Ended			12 Months Ended
		Jun. 30, 2021 USD ($) MWh MMBTU gal		Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) MWh MMBTU gal		Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) MWh MMBTU gal
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		$ 105,400,000			$ 105,400,000			$ 3,400,000
Cash Collateral Paid Netted Against Risk Management Liabilities		12,400,000			12,400,000			6,800,000
Fair Value of Derivative Instruments
Current Risk Management Assets		214,700,000			214,700,000			94,700,000
Long-term Risk Management Assets		241,300,000			241,300,000			242,200,000
Total Assets		456,000,000.0			456,000,000.0			336,900,000
Current Risk Management Liabilities		47,800,000			47,800,000			78,800,000
Long-term Risk Management Liabilities		216,300,000			216,300,000			232,800,000
Total Liabilities		264,100,000			264,100,000			311,600,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		66,800,000		$ 78,800,000	96,200,000		$ 45,900,000
Carrying Amount of Hedged Asset (Liability)	[1],[2]	(967,400,000)			(967,400,000)			(995,900,000)
Cumulative Fair Value Hedging Adjustment in the Carrying Amount of the Hedged Asset (Liability)	[1],[2]	(24,200,000)			(24,200,000)			(51,700,000)
Gain (Loss) on Hedging Instruments
Gain (Loss) on Fair Value Hedging Instruments	[3]	9,500,000		100,000	(23,700,000)		42,600,000
Gain (Loss) on Fair Value Portion of Long Term Debt	[3]	(9,500,000)		(100,000)	23,700,000		(42,600,000)
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		118,400,000			118,400,000			188,400,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		70,200,000			70,200,000			169,200,000
Derivatives and Hedging (Textuals) [Abstract]
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)		(49,000,000)			(49,000,000)			(53,000,000)
Credit Downgrade Trigger Exposure		8,000,000			8,000,000
Investment in Private Investee
Derivatives and Hedging (Textuals) [Abstract]
Cost Method Investments								8,000,000
Equity Method Investments, Fair Value Disclosure		46,000,000			46,000,000
Unrealized Gain (Loss) on Investments		11,000,000			38,000,000
AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		700,000		200,000	1,300,000		(1,200,000)
Appalachian Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		700,000			700,000			400,000
Cash Collateral Paid Netted Against Risk Management Liabilities		5,300,000			5,300,000			0
Fair Value of Derivative Instruments
Current Risk Management Assets		37,100,000			37,100,000			22,400,000
Total Assets								22,500,000
Total Liabilities								4,700,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		12,100,000		28,500,000	16,200,000		12,500,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		600,000			600,000			4,300,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		0			0			3,500,000
Indiana Michigan Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		300,000			300,000			1,700,000
Cash Collateral Paid Netted Against Risk Management Liabilities		4,500,000			4,500,000			0
Fair Value of Derivative Instruments
Current Risk Management Assets		7,700,000			7,700,000			3,600,000
Current Risk Management Liabilities		1,100,000			1,100,000			100,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(1,500,000)		3,100,000	(5,500,000)		5,700,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		400,000			400,000			500,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		0			0			100,000
Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Liabilities		7,300,000			7,300,000			8,700,000
Long-term Risk Management Liabilities		98,200,000			98,200,000			101,600,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		1,200,000		7,000,000.0	10,900,000		(8,000,000.0)
Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		23,000,000.0			23,000,000.0			10,300,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		15,100,000		12,700,000	26,400,000		20,300,000
Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		14,000,000.0			14,000,000.0			3,200,000
Long-term Risk Management Assets		600,000			600,000			0
Current Risk Management Liabilities		0			0			700,000
Long-term Risk Management Liabilities		0			0			1,000,000.0
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		20,300,000		10,600,000	27,400,000		11,900,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		0			0			1,800,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		0			0			1,800,000
Risk Management Contracts [Member]
Fair Value of Derivative Instruments
Total Assets	[4]	307,100,000	[5]		307,100,000	[5]		322,100,000	[6]
Total Liabilities	[4]	229,700,000	[5]		229,700,000	[5]		218,900,000	[6]
Risk Management Contracts [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Total Assets	[4]	0			0			0
Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	37,100,000			37,100,000			20,100,000
Total Liabilities	[4],[7]	1,400,000			1,400,000			1,300,000
Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	7,700,000			7,700,000			3,700,000
Total Liabilities	[4],[7]	1,100,000			1,100,000			200,000
Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	0			0			0
Total Liabilities	[4],[7]	105,500,000			105,500,000			110,300,000
Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	23,000,000.0			23,000,000.0			10,300,000
Total Liabilities	[4],[7]	100,000			100,000
Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	14,600,000			14,600,000			3,200,000
Total Liabilities	[4],[7]	0			0			1,700,000
Commodity [Member]
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		110,300,000			110,300,000			(60,600,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ 82,900,000			(27,100,000)
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows					117 months
Cross Default Provisions Maximum Third Party Obligation Amount		50,000,000			$ 50,000,000			50,000,000
Commodity [Member] | Risk Management Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	441,700,000			441,700,000			239,100,000
Long-term Risk Management Assets	[8]	276,600,000			276,600,000			275,900,000
Total Assets	[8]	718,300,000			718,300,000			515,000,000.0
Current Risk Management Liabilities	[8]	318,200,000			318,200,000			193,000,000.0
Long-term Risk Management Liabilities	[8]	229,700,000			229,700,000			222,200,000
Total Liabilities	[8]	547,900,000			547,900,000			415,200,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	170,400,000			170,400,000			99,800,000
Commodity [Member] | Risk Management Contracts [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	1,000,000.0			1,000,000.0			400,000
Long-term Risk Management Assets	[8]	100,000			100,000			0
Total Assets	[8]	1,100,000			1,100,000			400,000
Current Risk Management Liabilities	[8]	0			0			0
Long-term Risk Management Liabilities	[8]	0			0			0
Total Liabilities	[8]	0			0			0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	1,100,000			1,100,000			400,000
Commodity [Member] | Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	64,200,000			64,200,000			38,800,000
Long-term Risk Management Assets	[8]	100,000			100,000			700,000
Total Assets	[8]	64,300,000			64,300,000			39,500,000
Current Risk Management Liabilities	[8]	33,200,000			33,200,000			19,700,000
Long-term Risk Management Liabilities	[8]	0			0			600,000
Total Liabilities	[8]	33,200,000			33,200,000			20,300,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	31,100,000			31,100,000			19,200,000
Commodity [Member] | Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	25,900,000			25,900,000			17,200,000
Long-term Risk Management Assets	[8]	0			0			500,000
Total Assets	[8]	25,900,000			25,900,000			17,700,000
Current Risk Management Liabilities	[8]	23,500,000			23,500,000			12,100,000
Long-term Risk Management Liabilities	[8]	0			0			400,000
Total Liabilities	[8]	23,500,000			23,500,000			12,500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	2,400,000			2,400,000			5,200,000
Commodity [Member] | Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	700,000			700,000			300,000
Long-term Risk Management Assets	[8]	100,000			100,000			0
Total Assets	[8]	800,000			800,000			300,000
Current Risk Management Liabilities	[8]	7,300,000			7,300,000			8,700,000
Long-term Risk Management Liabilities	[8]	98,200,000			98,200,000			101,600,000
Total Liabilities	[8]	105,500,000			105,500,000			110,300,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(104,700,000)			(104,700,000)			(110,000,000.0)
Commodity [Member] | Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	23,500,000			23,500,000			10,500,000
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	23,500,000			23,500,000			10,500,000
Current Risk Management Liabilities	[8]	200,000			200,000			0
Long-term Risk Management Liabilities	[8]	0			0			0
Total Liabilities	[8]	200,000			200,000			0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	23,300,000			23,300,000			10,500,000
Commodity [Member] | Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	14,900,000			14,900,000			3,400,000
Long-term Risk Management Assets	[8]	700,000			700,000			0
Total Assets	[8]	15,600,000			15,600,000			3,400,000
Current Risk Management Liabilities	[8]	400,000			400,000			700,000
Long-term Risk Management Liabilities	[8]	0			0			1,000,000.0
Total Liabilities	[8]	400,000			400,000			1,700,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	15,200,000			15,200,000			1,700,000
Commodity [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	128,300,000			128,300,000			21,100,000
Long-term Risk Management Assets	[8]	52,800,000			52,800,000			18,000,000.0
Total Assets	[8]	181,100,000			181,100,000			39,100,000
Current Risk Management Liabilities	[8]	23,400,000			23,400,000			54,400,000
Long-term Risk Management Liabilities	[8]	18,000,000.0			18,000,000.0			60,100,000
Total Liabilities	[8]	41,400,000			41,400,000			114,500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	139,700,000			139,700,000			(75,400,000)
Interest Rate [Member]
Commodity:
Derivative, Notional Amount		950,000,000.0			950,000,000.0			1,150,000,000.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(32,200,000)			(32,200,000)			(47,500,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ (4,700,000)			(5,700,000)
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows					114 months
Deferred (Gain) Loss on Discontinuation of Fair Value Hedge		57,000,000			$ 57,000,000
Notional Amount of a Discontinued Hedge		500,000,000			500,000,000
Interest Rate [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(1,800,000)			(1,800,000)			(2,300,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					(1,100,000)			(1,100,000)
Interest Rate [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			200,000,000.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		8,000,000.0			8,000,000.0			(800,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					800,000			400,000
Interest Rate [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(7,400,000)			(7,400,000)			(8,300,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					(1,600,000)			(1,600,000)
Interest Rate [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Interest Rate [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		0			0			100,000
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					0			100,000
Interest Rate [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		500,000			500,000			(300,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					(800,000)			(1,500,000)
Interest Rate [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	3,200,000			3,200,000			5,000,000.0
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	3,200,000			3,200,000			5,000,000.0
Current Risk Management Liabilities	[8]	0			0			3,400,000
Long-term Risk Management Liabilities	[8]	28,400,000			28,400,000			4,100,000
Total Liabilities	[8]	28,400,000			28,400,000			7,500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(25,200,000)			(25,200,000)			(2,500,000)
Interest Rate [Member] | Hedging Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]							2,400,000
Long-term Risk Management Assets	[8]							0
Total Assets	[8]							2,400,000
Current Risk Management Liabilities	[8]							3,400,000
Long-term Risk Management Liabilities	[8]							0
Total Liabilities	[8]							3,400,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]							(1,000,000.0)
Gross Amounts of Risk Management Assets/Liabilities Recognized [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		573,200,000			573,200,000			265,200,000
Long-term Risk Management Assets		329,400,000			329,400,000			293,900,000
Total Assets		902,600,000			902,600,000			559,100,000
Current Risk Management Liabilities		341,600,000			341,600,000			250,800,000
Long-term Risk Management Liabilities		276,100,000			276,100,000			286,400,000
Total Liabilities		617,700,000			617,700,000			537,200,000
Total MTM Derivative Contract Net Assets (Liabilities)		284,900,000			284,900,000			21,900,000
Gross Amounts of Risk Management Assets/Liabilities Recognized [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets								41,200,000
Long-term Risk Management Assets								700,000
Total Assets								41,900,000
Current Risk Management Liabilities								23,100,000
Long-term Risk Management Liabilities								600,000
Total Liabilities								23,700,000
Total MTM Derivative Contract Net Assets (Liabilities)								18,200,000
Gross Amounts Offset in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(358,500,000)			(358,500,000)			(170,500,000)
Long-term Risk Management Assets	[9]	(88,100,000)			(88,100,000)			(51,700,000)
Total Assets	[9]	(446,600,000)			(446,600,000)			(222,200,000)
Current Risk Management Liabilities	[9]	(293,800,000)			(293,800,000)			(172,000,000.0)
Long-term Risk Management Liabilities	[9]	(59,800,000)			(59,800,000)			(53,600,000)
Total Liabilities	[9]	(353,600,000)			(353,600,000)			(225,600,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	(93,000,000.0)			(93,000,000.0)			3,400,000
Gross Amounts Offset in the Statement of Financial Position [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(1,000,000.0)			(1,000,000.0)			(400,000)
Long-term Risk Management Assets	[9]	(100,000)			(100,000)			0
Total Assets	[9]	(1,100,000)			(1,100,000)			(400,000)
Current Risk Management Liabilities	[9]	0			0			0
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	0			0			0
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	(1,100,000)			(1,100,000)			(400,000)
Gross Amounts Offset in the Statement of Financial Position [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(27,100,000)			(27,100,000)			(18,800,000)
Long-term Risk Management Assets	[9]	(100,000)			(100,000)			(600,000)
Total Assets	[9]	(27,200,000)			(27,200,000)			(19,400,000)
Current Risk Management Liabilities	[9]	(31,800,000)			(31,800,000)			(18,500,000)
Long-term Risk Management Liabilities	[9]	0			0			(500,000)
Total Liabilities	[9]	(31,800,000)			(31,800,000)			(19,000,000.0)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	4,600,000			4,600,000			(400,000)
Gross Amounts Offset in the Statement of Financial Position [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(18,200,000)			(18,200,000)			(13,600,000)
Long-term Risk Management Assets	[9]	0			0			(400,000)
Total Assets	[9]	(18,200,000)			(18,200,000)			(14,000,000.0)
Current Risk Management Liabilities	[9]	(22,400,000)			(22,400,000)			(12,000,000.0)
Long-term Risk Management Liabilities	[9]	0			0			(300,000)
Total Liabilities	[9]	(22,400,000)			(22,400,000)			(12,300,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	4,200,000			4,200,000			(1,700,000)
Gross Amounts Offset in the Statement of Financial Position [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(700,000)			(700,000)			(300,000)
Long-term Risk Management Assets	[9]	(100,000)			(100,000)			0
Total Assets	[9]	(800,000)			(800,000)			(300,000)
Current Risk Management Liabilities	[9]	0			0			0
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	0			0			0
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	(800,000)			(800,000)			(300,000)
Gross Amounts Offset in the Statement of Financial Position [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(500,000)			(500,000)			(200,000)
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	(500,000)			(500,000)			(200,000)
Current Risk Management Liabilities	[9]	(100,000)			(100,000)			0
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(100,000)			(100,000)			0
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	(400,000)			(400,000)			(200,000)
Gross Amounts Offset in the Statement of Financial Position [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(900,000)			(900,000)			(200,000)
Long-term Risk Management Assets	[9]	(100,000)			(100,000)			0
Total Assets	[9]	(1,000,000.0)			(1,000,000.0)			(200,000)
Current Risk Management Liabilities	[9]	(400,000)			(400,000)			0
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(400,000)			(400,000)			0
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	(600,000)			(600,000)			(200,000)
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	214,700,000			214,700,000			94,700,000
Long-term Risk Management Assets	[10]	241,300,000			241,300,000			242,200,000
Total Assets	[10]	456,000,000.0			456,000,000.0			336,900,000
Current Risk Management Liabilities	[10]	47,800,000			47,800,000			78,800,000
Long-term Risk Management Liabilities	[10]	216,300,000			216,300,000			232,800,000
Total Liabilities	[10]	264,100,000			264,100,000			311,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	191,900,000			191,900,000			25,300,000
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	0			0			0
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	0			0			0
Current Risk Management Liabilities	[10]	0			0			0
Long-term Risk Management Liabilities	[10]	0			0			0
Total Liabilities	[10]	0			0			0
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	0			0			0
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	37,100,000			37,100,000			22,400,000
Long-term Risk Management Assets	[10]	0			0			100,000
Total Assets	[10]	37,100,000			37,100,000			22,500,000
Current Risk Management Liabilities	[10]	1,400,000			1,400,000			4,600,000
Long-term Risk Management Liabilities	[10]	0			0			100,000
Total Liabilities	[10]	1,400,000			1,400,000			4,700,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	35,700,000			35,700,000			17,800,000
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	7,700,000			7,700,000			3,600,000
Long-term Risk Management Assets	[10]	0			0			100,000
Total Assets	[10]	7,700,000			7,700,000			3,700,000
Current Risk Management Liabilities	[10]	1,100,000			1,100,000			100,000
Long-term Risk Management Liabilities	[10]	0			0			100,000
Total Liabilities	[10]	1,100,000			1,100,000			200,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	6,600,000			6,600,000			3,500,000
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	0			0			0
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	0			0			0
Current Risk Management Liabilities	[10]	7,300,000			7,300,000			8,700,000
Long-term Risk Management Liabilities	[10]	98,200,000			98,200,000			101,600,000
Total Liabilities	[10]	105,500,000			105,500,000			110,300,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	(105,500,000)			(105,500,000)			(110,300,000)
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	23,000,000.0			23,000,000.0			10,300,000
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	23,000,000.0			23,000,000.0			10,300,000
Current Risk Management Liabilities	[10]	100,000			100,000			0
Long-term Risk Management Liabilities	[10]	0			0			0
Total Liabilities	[10]	100,000			100,000			0
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	22,900,000			22,900,000			10,300,000
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	14,000,000.0			14,000,000.0			3,200,000
Long-term Risk Management Assets	[10]	600,000			600,000			0
Total Assets	[10]	14,600,000			14,600,000			3,200,000
Current Risk Management Liabilities	[10]	0			0			700,000
Long-term Risk Management Liabilities	[10]	0			0			1,000,000.0
Total Liabilities	[10]	0			0			1,700,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	$ 14,600,000			$ 14,600,000			$ 1,500,000
Power [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		412.5			412.5			331.3
Power [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		0.0			0.0			0.0
Power [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		77.9			77.9			46.9
Power [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		32.4			32.4			19.7
Power [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		2.8			2.8			3.0
Power [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		26.8			26.8			11.9
Power [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		7.2			7.2			4.0
Natural Gas [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		24.3			24.3			26.9
Natural Gas [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.0			0.0			0.0
Natural Gas [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.0			0.0			0.0
Natural Gas [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.0			0.0			0.0
Natural Gas [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.0			0.0			0.0
Natural Gas [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.0			0.0			0.0
Natural Gas [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		6.1			6.1			7.9
Heating Oil and Gasoline [Member]
Commodity:
Derivative, Volume Notional Amount | gal		9.7			9.7			6.9
Heating Oil and Gasoline [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Volume Notional Amount | gal		2.5			2.5			1.8
Heating Oil and Gasoline [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.5			1.5			1.1
Heating Oil and Gasoline [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.9			0.9			0.6
Heating Oil and Gasoline [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.9			1.9			1.4
Heating Oil and Gasoline [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.1			1.1			0.7
Heating Oil and Gasoline [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.3			1.3			0.9
Interest Rate Contract [Member]
Commodity:
Derivative, Notional Amount		$ 123,600,000			$ 123,600,000			$ 129,800,000
Interest Rate Contract [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Interest Rate Contract [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Interest Rate Contract [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Interest Rate Contract [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Interest Rate Contract [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Interest Rate Contract [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Notional Amount		0			0			0
Warrants Held in Investee
Fair Value of Derivative Instruments
Total Assets		26,000,000			26,000,000			$ 32,000,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		4,000,000			(6,000,000)
Vertically Integrated Utilities Revenues [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	300,000		300,000
Vertically Integrated Utilities Revenues [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Vertically Integrated Utilities Revenues [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Vertically Integrated Utilities Revenues [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Vertically Integrated Utilities Revenues [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Vertically Integrated Utilities Revenues [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Vertically Integrated Utilities Revenues [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Generation and Marketing Revenues [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		16,500,000		9,900,000	16,100,000		(400,000)
Generation and Marketing Revenues [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Generation and Marketing Revenues [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Generation and Marketing Revenues [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Generation and Marketing Revenues [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Generation and Marketing Revenues [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Generation and Marketing Revenues [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Electric Generation, Transmission and Distribution Revenues [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Electric Generation, Transmission and Distribution Revenues [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Electric Generation, Transmission and Distribution Revenues [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	300,000		100,000
Electric Generation, Transmission and Distribution Revenues [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		100,000
Electric Generation, Transmission and Distribution Revenues [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Electric Generation, Transmission and Distribution Revenues [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Electric Generation, Transmission and Distribution Revenues [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		100,000	0		100,000
Purchased Electricity for Resale [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		600,000		800,000	1,000,000.0		900,000
Purchased Electricity for Resale [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Purchased Electricity for Resale [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		500,000		700,000	900,000		800,000
Purchased Electricity for Resale [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		0	100,000		0
Purchased Electricity for Resale [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Purchased Electricity for Resale [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Purchased Electricity for Resale [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		0	0		0
Other Operation Expense [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		700,000		(800,000)	1,000,000.0		(1,000,000.0)
Other Operation Expense [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		200,000		(200,000)	300,000		(300,000)
Other Operation Expense [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	100,000		(100,000)
Other Operation Expense [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	100,000		(100,000)
Other Operation Expense [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	200,000		(200,000)
Other Operation Expense [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	100,000		(100,000)
Other Operation Expense [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	100,000		(100,000)
Maintenance Expense [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		800,000		(1,200,000)	1,300,000		(1,400,000)
Maintenance Expense [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		300,000		(300,000)	400,000		(400,000)
Maintenance Expense [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(100,000)	200,000		(200,000)
Maintenance Expense [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		(100,000)	100,000		(100,000)
Maintenance Expense [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(200,000)	200,000		(200,000)
Maintenance Expense [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0		(200,000)	100,000		(200,000)
Maintenance Expense [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		100,000		(200,000)	200,000		(200,000)
Regulatory Assets [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	(7,000,000.0)		17,500,000	(600,000)		(16,400,000)
Regulatory Assets [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	0		700,000	0		(500,000)
Regulatory Assets [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	0		8,400,000	0		(500,000)
Regulatory Assets [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	(5,100,000)		300,000	(6,000,000.0)		(400,000)
Regulatory Assets [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	(1,200,000)		4,100,000	5,400,000		(14,300,000)
Regulatory Assets [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	0		300,000	0		(200,000)
Regulatory Assets [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	500,000		1,300,000	1,300,000		(700,000)
Regulatory Liabilities [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	55,100,000		52,700,000	77,100,000		63,900,000
Regulatory Liabilities [Member] | AEP Texas Inc. [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	200,000		0	600,000		0
Regulatory Liabilities [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	11,300,000		19,700,000	14,700,000		12,400,000
Regulatory Liabilities [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	3,400,000		3,000,000.0	200,000		6,200,000
Regulatory Liabilities [Member] | Ohio Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	2,200,000		3,200,000	5,100,000		6,700,000
Regulatory Liabilities [Member] | Public Service Co Of Oklahoma [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	15,000,000.0		12,700,000	26,200,000		20,800,000
Regulatory Liabilities [Member] | Southwestern Electric Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	$ 19,600,000		$ 9,500,000	$ 25,800,000		$ 12,800,000

[1] Amounts include $(49) million and $(53) million as of June 30, 2021 and December 31, 2020, respectively, for the fair value hedge adjustment of hedged debt obligations for which hedge accounting has been discontinued.

[2] Amounts included on the balance sheets within Long-term Debt Due within One Year and Long-term Debt, respectively.

[3] Gain (Loss) is included in Interest Expense on the statements of income.

[4] Amounts in “Other’’ column primarily represent counterparty netting of risk management and hedging contracts and associated cash collateral under the accounting guidance for “Derivatives and Hedging.’’

[5] The June 30, 2021 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows: Level 1 matures $2 million in periods 2022-2024; Level 2 matures $11 million in 2021, $37 million in periods 2022-2024, $22 million in periods 2025-2026 and $13 million in periods 2027-2033; Level 3 matures $96 million in 2021, $12 million in periods 2022-2024, $4 million in periods 2025-2026 and $(27) million in periods 2027-2033.  Risk management commodity contracts are substantially comprised of power contracts.

[6] The December 31, 2020 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows: Level 2 matures $3 million in periods 2022-2024, $11 million in periods 2025-2026 and $1 million in periods 2027-2033; Level 3 matures $47 million in 2021, $37 million in periods 2022-2024, $14 million in periods 2025-2026 and $(13) million in periods 2027-2033.  Risk management commodity contracts are substantially comprised of power contracts.

[7] Substantially comprised of power contracts for the Registrant Subsidiaries.

[8] Derivative instruments within these categories are reported gross.  These instruments are subject to master netting agreements and are presented on the balance sheets on a net basis in accordance with the accounting guidance for “Derivatives and Hedging.”

[9] Amounts include counterparty netting of risk management and hedging contracts and associated cash collateral in accordance with the accounting guidance for “Derivatives and Hedging.”

[10] All derivative contracts subject to a master netting arrangement or similar agreement are offset in the statement of financial position.

[11] Represents realized and unrealized gains and losses subject to regulatory accounting treatment recorded as either current or noncurrent on the balance sheets.