Derivatives and Hedging (Details) gal in Millions, MWh in Millions, MMBTU in Millions		3 Months Ended			6 Months Ended			12 Months Ended
		Jun. 30, 2020 USD ($) MWh MMBTU gal		Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) MWh MMBTU gal		Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) MMBTU MWh gal
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		$ 0			$ 0			$ 5,000,000
Cash Collateral Paid Netted Against Risk Management Liabilities		36,000,000			36,000,000			39,000,000
Fair Value of Derivative Instruments
Current Risk Management Assets		150,100,000			150,100,000			172,800,000
Long-term Risk Management Assets		247,100,000			247,100,000			266,600,000
Total Assets		397,200,000			397,200,000			439,400,000
Current Risk Management Liabilities		102,500,000			102,500,000			114,300,000
Long-term Risk Management Liabilities		245,200,000			245,200,000			261,800,000
Total Liabilities		347,700,000			347,700,000			376,100,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		78,800,000		$ 55,500,000	45,900,000		$ 30,600,000
Carrying Amount of Hedged Asset (Liability)	[1],[2]	(553,700,000)			(553,700,000)			(510,800,000)
Cumulative Fair Value Hedging Adjustment in the Carrying Amount of the Hedged Asset (Liability)	[1],[2]	(57,100,000)			(57,100,000)			(14,500,000)
Gain (Loss) on Hedging Instruments
Gain (Loss) on Fair Value Hedging Instruments	[3]	100,000		18,200,000	42,600,000		29,300,000
Gain (Loss) on Fair Value Portion of Long Term Debt	[3]	(100,000)		(18,200,000)	(42,600,000)		(29,300,000)
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		239,500,000			239,500,000			267,300,000
Amount of Cash Collateral Posted		2,800,000			2,800,000			3,700,000
Additional Settlement Liability if Cross Default Provision is Triggered		208,000,000.0			208,000,000.0			246,700,000
Derivatives and Hedging (Textuals) [Abstract]
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)		(57,000,000)			(57,000,000)			0
AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Liabilities		100,000			100,000			0
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		200,000		(100,000)	(1,200,000)		300,000
Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		37,700,000			37,700,000			39,400,000
Long-term Risk Management Assets		400,000			400,000			100,000
Total Assets		38,100,000			38,100,000
Current Risk Management Liabilities		7,600,000			7,600,000			1,900,000
Long-term Risk Management Liabilities		200,000			200,000			0
Total Liabilities		7,800,000			7,800,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		28,500,000		19,900,000	12,500,000		(14,100,000)
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		6,400,000			6,400,000			2,300,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		5,900,000			5,900,000			400,000
Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		6,400,000			6,400,000			9,800,000
Long-term Risk Management Assets		300,000			300,000			100,000
Current Risk Management Liabilities		300,000			300,000			500,000
Long-term Risk Management Liabilities		200,000			200,000			0
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		3,100,000		7,400,000	5,700,000		14,600,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		300,000			300,000			1,300,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		0			0			200,000
Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Liabilities		8,600,000			8,600,000			7,300,000
Long-term Risk Management Liabilities		108,900,000			108,900,000			96,300,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		7,000,000.0		(8,300,000)	(8,000,000.0)		(17,400,000)
Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		23,800,000			23,800,000			15,800,000
Current Risk Management Liabilities		100,000			100,000			0
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		12,700,000		16,600,000	20,300,000		23,300,000
Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		6,900,000			6,900,000			6,400,000
Current Risk Management Liabilities		1,600,000			1,600,000			1,900,000
Long-term Risk Management Liabilities		2,100,000			2,100,000			3,100,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		10,600,000		14,900,000	11,900,000		19,500,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		4,000,000.0			4,000,000.0			5,100,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		4,000,000.0			4,000,000.0			5,100,000
Risk Management Contracts [Member]
Fair Value of Derivative Instruments
Total Assets	[4]	384,500,000	[5]		384,500,000	[5]		408,800,000	[6]
Total Liabilities	[4]	228,300,000	[5]		228,300,000	[5]		239,000,000.0	[6]
Risk Management Contracts [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Total Liabilities	[4]	100,000			100,000
Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	38,000,000.0			38,000,000.0			39,500,000
Total Liabilities	[4],[7]	1,900,000			1,900,000			1,900,000
Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	6,700,000			6,700,000			9,900,000
Total Liabilities	[4],[7]	500,000			500,000			500,000
Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Total Liabilities	[4],[7]	117,500,000			117,500,000			103,600,000
Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	23,800,000			23,800,000			15,800,000
Total Liabilities	[4],[7]	100,000			100,000			0
Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	6,900,000			6,900,000			6,400,000
Total Liabilities	[4],[7]	3,700,000			3,700,000			5,000,000.0
Commodity [Member]
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(81,400,000)			(81,400,000)			(103,500,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ (46,400,000)			(51,700,000)
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows					129 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]	349,500,000			349,500,000			513,900,000
Long-term Risk Management Assets	[8]	307,700,000			307,700,000			290,800,000
Total Assets	[8]	657,200,000			657,200,000			804,700,000
Current Risk Management Liabilities	[8]	264,500,000			264,500,000			424,500,000
Long-term Risk Management Liabilities	[8]	272,100,000			272,100,000			244,500,000
Total Liabilities	[8]	536,600,000			536,600,000			669,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	120,600,000			120,600,000			135,700,000
Commodity [Member] | Risk Management Contracts [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	0			0			0
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	0			0			0
Current Risk Management Liabilities	[8]	600,000			600,000			0
Long-term Risk Management Liabilities	[8]	0			0			0
Total Liabilities	[8]	600,000			600,000			0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(600,000)			(600,000)			0
Commodity [Member] | Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	71,200,000			71,200,000			124,400,000
Long-term Risk Management Assets	[8]	3,700,000			3,700,000			900,000
Total Assets	[8]	74,900,000			74,900,000			125,300,000
Current Risk Management Liabilities	[8]	35,800,000			35,800,000			86,200,000
Long-term Risk Management Liabilities	[8]	3,400,000			3,400,000			700,000
Total Liabilities	[8]	39,200,000			39,200,000			86,900,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	35,700,000			35,700,000			38,400,000
Commodity [Member] | Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	28,600,000			28,600,000			66,900,000
Long-term Risk Management Assets	[8]	2,200,000			2,200,000			500,000
Total Assets	[8]	30,800,000			30,800,000			67,400,000
Current Risk Management Liabilities	[8]	22,600,000			22,600,000			55,200,000
Long-term Risk Management Liabilities	[8]	2,200,000			2,200,000			400,000
Total Liabilities	[8]	24,800,000			24,800,000			55,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	6,000,000.0			6,000,000.0			11,800,000
Commodity [Member] | Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	0			0			0
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	0			0			0
Current Risk Management Liabilities	[8]	8,900,000			8,900,000			7,300,000
Long-term Risk Management Liabilities	[8]	108,900,000			108,900,000			96,300,000
Total Liabilities	[8]	117,800,000			117,800,000			103,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(117,800,000)			(117,800,000)			(103,600,000)
Commodity [Member] | Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	23,900,000			23,900,000			16,300,000
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	23,900,000			23,900,000			16,300,000
Current Risk Management Liabilities	[8]	300,000			300,000			500,000
Long-term Risk Management Liabilities	[8]	0			0			0
Total Liabilities	[8]	300,000			300,000			500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	23,600,000			23,600,000			15,800,000
Commodity [Member] | Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	7,000,000.0			7,000,000.0			6,500,000
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	7,000,000.0			7,000,000.0			6,500,000
Current Risk Management Liabilities	[8]	1,900,000			1,900,000			2,000,000.0
Long-term Risk Management Liabilities	[8]	2,100,000			2,100,000			3,100,000
Total Liabilities	[8]	4,000,000.0			4,000,000.0			5,100,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	3,000,000.0			3,000,000.0			1,400,000
Commodity [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	15,400,000			15,400,000			11,500,000
Long-term Risk Management Assets	[8]	19,100,000			19,100,000			11,000,000.0
Total Assets	[8]	34,500,000			34,500,000			22,500,000
Current Risk Management Liabilities	[8]	72,100,000			72,100,000			72,300,000
Long-term Risk Management Liabilities	[8]	63,300,000			63,300,000			75,700,000
Total Liabilities	[8]	135,400,000			135,400,000			148,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(100,900,000)			(100,900,000)			(125,500,000)
Interest Rate [Member]
Commodity:
Derivative, Notional Amount		200,000,000.0			200,000,000.0			625,000,000.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(55,300,000)			(55,300,000)			(11,500,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ (4,800,000)			(2,100,000)
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows					126 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		(2,900,000)			(2,900,000)			(3,400,000)
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		200,000,000.0			200,000,000.0			0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(4,100,000)			(4,100,000)			900,000
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					900,000			900,000
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		(9,100,000)			(9,100,000)			(9,900,000)
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		600,000			600,000			1,100,000
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					600,000			1,000,000.0
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		(1,100,000)			(1,100,000)			(1,800,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					(1,500,000)			(1,500,000)
Interest Rate [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	100,000			100,000			6,500,000
Long-term Risk Management Assets	[8]	0			0			12,600,000
Total Assets	[8]	100,000			100,000			19,100,000
Current Risk Management Liabilities	[8]	5,900,000			5,900,000			0
Long-term Risk Management Liabilities	[8]	0			0			0
Total Liabilities	[8]	5,900,000			5,900,000			0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(5,800,000)			(5,800,000)			19,100,000
Interest Rate [Member] | Hedging Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	100,000			100,000
Long-term Risk Management Assets	[8]	0			0
Total Assets	[8]	100,000			100,000
Current Risk Management Liabilities	[8]	5,900,000			5,900,000
Long-term Risk Management Liabilities	[8]	0			0
Total Liabilities	[8]	5,900,000			5,900,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(5,800,000)			(5,800,000)
Gross Amounts of Risk Management Assets/Liabilities Recognized [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		365,000,000.0			365,000,000.0			531,900,000
Long-term Risk Management Assets		326,800,000			326,800,000			314,400,000
Total Assets		691,800,000			691,800,000			846,300,000
Current Risk Management Liabilities		342,500,000			342,500,000			496,800,000
Long-term Risk Management Liabilities		335,400,000			335,400,000			320,200,000
Total Liabilities		677,900,000			677,900,000			817,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)		13,900,000			13,900,000			29,300,000
Gross Amounts Offset in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(214,900,000)			(214,900,000)			(359,100,000)
Long-term Risk Management Assets	[9]	(79,700,000)			(79,700,000)			(47,800,000)
Total Assets	[9]	(294,600,000)			(294,600,000)			(406,900,000)
Current Risk Management Liabilities	[9]	(240,000,000.0)			(240,000,000.0)			(382,500,000)
Long-term Risk Management Liabilities	[9]	(90,200,000)			(90,200,000)			(58,400,000)
Total Liabilities	[9]	(330,200,000)			(330,200,000)			(440,900,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	35,600,000			35,600,000			34,000,000.0
Gross Amounts Offset in the Statement of Financial Position [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	0			0			0
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	0			0			0
Current Risk Management Liabilities	[9]	(500,000)			(500,000)			0
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(500,000)			(500,000)			0
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	500,000			500,000			0
Gross Amounts Offset in the Statement of Financial Position [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(33,600,000)			(33,600,000)			(85,000,000.0)
Long-term Risk Management Assets	[9]	(3,300,000)			(3,300,000)			(800,000)
Total Assets	[9]	(36,900,000)			(36,900,000)			(85,800,000)
Current Risk Management Liabilities	[9]	(34,100,000)			(34,100,000)			(84,300,000)
Long-term Risk Management Liabilities	[9]	(3,200,000)			(3,200,000)			(700,000)
Total Liabilities	[9]	(37,300,000)			(37,300,000)			(85,000,000.0)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	400,000			400,000			(800,000)
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]	(22,200,000)			(22,200,000)			(57,100,000)
Long-term Risk Management Assets	[9]	(1,900,000)			(1,900,000)			(400,000)
Total Assets	[9]	(24,100,000)			(24,100,000)			(57,500,000)
Current Risk Management Liabilities	[9]	(22,300,000)			(22,300,000)			(54,700,000)
Long-term Risk Management Liabilities	[9]	(2,000,000.0)			(2,000,000.0)			(400,000)
Total Liabilities	[9]	(24,300,000)			(24,300,000)			(55,100,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	200,000			200,000			(2,400,000)
Gross Amounts Offset in the Statement of Financial Position [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	0			0			0
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	0			0			0
Current Risk Management Liabilities	[9]	(300,000)			(300,000)			0
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(300,000)			(300,000)			0
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	300,000			300,000			0
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]	(100,000)			(100,000)			(500,000)
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	(100,000)			(100,000)			(500,000)
Current Risk Management Liabilities	[9]	(200,000)			(200,000)			(500,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(200,000)			(200,000)			(500,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	100,000			100,000			0
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]	(100,000)			(100,000)			(100,000)
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	(100,000)			(100,000)			(100,000)
Current Risk Management Liabilities	[9]	(300,000)			(300,000)			(100,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(300,000)			(300,000)			(100,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	200,000			200,000			0
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	150,100,000			150,100,000			172,800,000
Long-term Risk Management Assets	[10]	247,100,000			247,100,000			266,600,000
Total Assets	[10]	397,200,000			397,200,000			439,400,000
Current Risk Management Liabilities	[10]	102,500,000			102,500,000			114,300,000
Long-term Risk Management Liabilities	[10]	245,200,000			245,200,000			261,800,000
Total Liabilities	[10]	347,700,000			347,700,000			376,100,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	49,500,000			49,500,000			63,300,000
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]	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]	(100,000)			(100,000)			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]	37,700,000			37,700,000			39,400,000
Long-term Risk Management Assets	[10]	400,000			400,000			100,000
Total Assets	[10]	38,100,000			38,100,000			39,500,000
Current Risk Management Liabilities	[10]	7,600,000			7,600,000			1,900,000
Long-term Risk Management Liabilities	[10]	200,000			200,000			0
Total Liabilities	[10]	7,800,000			7,800,000			1,900,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	30,300,000			30,300,000			37,600,000
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]	6,400,000			6,400,000			9,800,000
Long-term Risk Management Assets	[10]	300,000			300,000			100,000
Total Assets	[10]	6,700,000			6,700,000			9,900,000
Current Risk Management Liabilities	[10]	300,000			300,000			500,000
Long-term Risk Management Liabilities	[10]	200,000			200,000			0
Total Liabilities	[10]	500,000			500,000			500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	6,200,000			6,200,000			9,400,000
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]	8,600,000			8,600,000			7,300,000
Long-term Risk Management Liabilities	[10]	108,900,000			108,900,000			96,300,000
Total Liabilities	[10]	117,500,000			117,500,000			103,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	(117,500,000)			(117,500,000)			(103,600,000)
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]	23,800,000			23,800,000			15,800,000
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	23,800,000			23,800,000			15,800,000
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]	23,700,000			23,700,000			15,800,000
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]	6,900,000			6,900,000			6,400,000
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	6,900,000			6,900,000			6,400,000
Current Risk Management Liabilities	[10]	1,600,000			1,600,000			1,900,000
Long-term Risk Management Liabilities	[10]	2,100,000			2,100,000			3,100,000
Total Liabilities	[10]	3,700,000			3,700,000			5,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	$ 3,200,000			$ 3,200,000			$ 1,400,000
Power [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		463.9			463.9			365.9
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		98.1			98.1			61.0
Power [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		39.7			39.7			26.8
Power [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		3.1			3.1			7.1
Power [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		32.0			32.0			14.9
Power [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		9.6			9.6			4.4
Natural Gas [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		36.8			36.8			40.7
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		9.7			9.7			11.6
Heating Oil and Gasoline [Member]
Commodity:
Derivative, Volume Notional Amount | gal		10.2			10.2			6.9
Heating Oil and Gasoline [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Volume Notional Amount | gal		2.6			2.6			1.8
Heating Oil and Gasoline [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.6			1.6			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		2.0			2.0			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		1.4			1.4			0.9
Interest Rate Contract [Member]
Commodity:
Derivative, Notional Amount		$ 137,100,000			$ 137,100,000			$ 140,100,000
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
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)		200,000	300,000		500,000
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		9,900,000		3,500,000	(400,000)		6,200,000
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	100,000		0
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	100,000		300,000
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		100,000		0	100,000		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		800,000		(200,000)	900,000		1,200,000
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		700,000		1,100,000	800,000		1,100,000
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		0		100,000	0		100,000
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		(800,000)		(100,000)	(1,000,000.0)		(500,000)
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)		0	(300,000)		(100,000)
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)		0
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)		0	(100,000)		0
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)		0	(200,000)		(100,000)
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)		0	(100,000)		0
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		(1,200,000)		100,000	(1,400,000)		(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)		0	(400,000)		(100,000)
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)		(100,000)
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		(100,000)		0	(100,000)		0
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		(200,000)		0	(200,000)		(100,000)
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		(200,000)		0	(200,000)		0
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		(200,000)		0	(200,000)		(100,000)
Regulatory Assets [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	17,500,000		(8,200,000)	(16,400,000)		(14,600,000)
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]	700,000		(100,000)	(500,000)		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]	8,400,000		2,300,000	(500,000)		200,000
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]	300,000		(100,000)	(400,000)		200,000
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]	4,100,000		(8,300,000)	(14,300,000)		(17,200,000)
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]	300,000		500,000	(200,000)		1,000,000.0
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]	1,300,000		1,300,000	(700,000)		1,200,000
Regulatory Liabilities [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	52,700,000		60,200,000	63,900,000		38,200,000
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]	0		0	0		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]	19,700,000		16,400,000	12,400,000		(15,300,000)
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]	3,000,000.0		7,400,000	6,200,000		14,000,000.0
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]	3,200,000		0	6,700,000		0
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]	12,700,000		16,100,000	20,800,000		22,300,000
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]	$ 9,500,000		$ 13,700,000	$ 12,800,000		$ 18,400,000

[1] Amounts include $(57) million and $0 as of June 30, 2020 and December 31, 2019, 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, 2020 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 1 matures $(1) million in periods 2021-2023; Level 2 matures $(10) million in 2020, $(1) million in periods 2021-2023, $4 million in periods 2024-2025 and $10 million in periods 2026-2032; Level 3 matures $60 million in 2020, $61 million in periods 2021-2023, $20 million in periods 2024-2025 and $(22) million in periods 2026-2032.  Risk management commodity contracts are substantially comprised of power contracts.

[6] The December 31, 2019 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 2 matures $(7) million in 2020 and $(3) million in periods 2021-2023; Level 3 matures $96 million in 2020, $36 million in periods 2021-2023, $25 million in periods 2024-2025 and $(12) million in periods 2026-2032.  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.