Derivatives and Hedging (Details) gal in Millions, MWh in Millions, MMBTU in Millions		3 Months Ended			9 Months Ended			12 Months Ended
		Sep. 30, 2020 USD ($) MWh MMBTU gal		Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) MWh MMBTU gal		Sep. 30, 2019 USD ($)	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		9,000,000			9,000,000			39,000,000
Fair Value of Derivative Instruments
Current Risk Management Assets		115,200,000			115,200,000			172,800,000
Long-term Risk Management Assets		242,900,000			242,900,000			266,600,000
Total Assets		358,100,000			358,100,000			439,400,000
Current Risk Management Liabilities		62,400,000			62,400,000			114,300,000
Long-term Risk Management Liabilities		232,400,000			232,400,000			261,800,000
Total Liabilities		294,800,000			294,800,000			376,100,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		36,000,000.0		$ 43,100,000	81,900,000		$ 73,700,000
Carrying Amount of Hedged Asset (Liability)	[1],[2]	(551,900,000)			(551,900,000)			(510,800,000)
Cumulative Fair Value Hedging Adjustment in the Carrying Amount of the Hedged Asset (Liability)	[1],[2]	(55,200,000)			(55,200,000)			(14,500,000)
Gain (Loss) on Hedging Instruments
Gain (Loss) on Fair Value Hedging Instruments	[3]	0		13,200,000	42,600,000		42,500,000
Gain (Loss) on Fair Value Portion of Long Term Debt	[3]	0		(13,200,000)	(42,600,000)		(42,500,000)
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		189,700,000			189,700,000			267,300,000
Amount of Cash Collateral Posted		0			0			3,700,000
Additional Settlement Liability if Cross Default Provision is Triggered		162,300,000			162,300,000			246,700,000
Derivatives and Hedging (Textuals) [Abstract]
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)		(55,000,000)			(55,000,000)			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		(100,000)		(200,000)	(1,300,000)		100,000
Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		30,700,000			30,700,000			39,400,000
Long-term Risk Management Assets		100,000			100,000			100,000
Total Assets		30,800,000			30,800,000
Current Risk Management Liabilities		5,600,000			5,600,000			1,900,000
Long-term Risk Management Liabilities		200,000			200,000			0
Total Liabilities		5,800,000			5,800,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		4,500,000		10,600,000	17,000,000.0		(3,500,000)
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		5,700,000			5,700,000			2,300,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		5,300,000			5,300,000			400,000
Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		4,100,000			4,100,000			9,800,000
Long-term Risk Management Assets		0			0			100,000
Current Risk Management Liabilities		200,000			200,000			500,000
Long-term 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		2,700,000		3,200,000	8,400,000		17,800,000
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		8,200,000			8,200,000			7,300,000
Long-term Risk Management Liabilities		105,100,000			105,100,000			96,300,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		5,800,000		(2,700,000)	(2,200,000)		(20,100,000)
Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		16,600,000			16,600,000			15,800,000
Current Risk Management Liabilities		500,000			500,000			0
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		2,600,000		4,100,000	22,900,000		27,400,000
Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		4,500,000			4,500,000			6,400,000
Current Risk Management Liabilities		100,000			100,000			1,900,000
Long-term Risk Management Liabilities		700,000			700,000			3,100,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		4,700,000		2,900,000	16,600,000		22,400,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		900,000			900,000			5,100,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		900,000			900,000			5,100,000
Risk Management Contracts [Member]
Fair Value of Derivative Instruments
Total Assets	[4]	345,300,000	[5]		345,300,000	[5]		408,800,000	[6]
Total Liabilities	[4]	221,700,000	[5]		221,700,000	[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]	30,200,000			30,200,000			39,500,000
Total Liabilities	[4],[7]	500,000			500,000			1,900,000
Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	4,100,000			4,100,000			9,900,000
Total Liabilities	[4],[7]	300,000			300,000			500,000
Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Total Liabilities	[4],[7]	113,300,000			113,300,000			103,600,000
Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	16,600,000			16,600,000			15,800,000
Total Liabilities	[4],[7]	500,000			500,000			0
Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[4],[7]	4,500,000			4,500,000			6,400,000
Total Liabilities	[4],[7]	800,000			800,000			5,000,000.0
Commodity [Member]
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(45,100,000)			(45,100,000)			(103,500,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ (13,900,000)			(51,700,000)
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows					126 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]	253,700,000			253,700,000			513,900,000
Long-term Risk Management Assets	[8]	283,300,000			283,300,000			290,800,000
Total Assets	[8]	537,000,000.0			537,000,000.0			804,700,000
Current Risk Management Liabilities	[8]	183,100,000			183,100,000			424,500,000
Long-term Risk Management Liabilities	[8]	239,000,000.0			239,000,000.0			244,500,000
Total Liabilities	[8]	422,100,000			422,100,000			669,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	114,900,000			114,900,000			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]	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]	(200,000)			(200,000)			0
Commodity [Member] | Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	49,600,000			49,600,000			124,400,000
Long-term Risk Management Assets	[8]	1,600,000			1,600,000			900,000
Total Assets	[8]	51,200,000			51,200,000			125,300,000
Current Risk Management Liabilities	[8]	20,700,000			20,700,000			86,200,000
Long-term Risk Management Liabilities	[8]	1,800,000			1,800,000			700,000
Total Liabilities	[8]	22,500,000			22,500,000			86,900,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	28,700,000			28,700,000			38,400,000
Commodity [Member] | Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	16,500,000			16,500,000			66,900,000
Long-term Risk Management Assets	[8]	1,000,000.0			1,000,000.0			500,000
Total Assets	[8]	17,500,000			17,500,000			67,400,000
Current Risk Management Liabilities	[8]	13,100,000			13,100,000			55,200,000
Long-term Risk Management Liabilities	[8]	1,100,000			1,100,000			400,000
Total Liabilities	[8]	14,200,000			14,200,000			55,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	3,300,000			3,300,000			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]	8,300,000			8,300,000			7,300,000
Long-term Risk Management Liabilities	[8]	105,100,000			105,100,000			96,300,000
Total Liabilities	[8]	113,400,000			113,400,000			103,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(113,400,000)			(113,400,000)			(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]	16,600,000			16,600,000			16,300,000
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	16,600,000			16,600,000			16,300,000
Current Risk Management Liabilities	[8]	600,000			600,000			500,000
Long-term Risk Management Liabilities	[8]	0			0			0
Total Liabilities	[8]	600,000			600,000			500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	16,000,000.0			16,000,000.0			15,800,000
Commodity [Member] | Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	4,500,000			4,500,000			6,500,000
Long-term Risk Management Assets	[8]	0			0			0
Total Assets	[8]	4,500,000			4,500,000			6,500,000
Current Risk Management Liabilities	[8]	200,000			200,000			2,000,000.0
Long-term Risk Management Liabilities	[8]	700,000			700,000			3,100,000
Total Liabilities	[8]	900,000			900,000			5,100,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	3,600,000			3,600,000			1,400,000
Commodity [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	24,500,000			24,500,000			11,500,000
Long-term Risk Management Assets	[8]	17,500,000			17,500,000			11,000,000.0
Total Assets	[8]	42,000,000.0			42,000,000.0			22,500,000
Current Risk Management Liabilities	[8]	40,600,000			40,600,000			72,300,000
Long-term Risk Management Liabilities	[8]	57,000,000.0			57,000,000.0			75,700,000
Total Liabilities	[8]	97,600,000			97,600,000			148,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(55,600,000)			(55,600,000)			(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		(52,300,000)			(52,300,000)			(11,500,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ (5,300,000)			(2,100,000)
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows					123 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		(2,600,000)			(2,600,000)			(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		(3,500,000)			(3,500,000)			900,000
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					600,000			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		(8,700,000)			(8,700,000)			(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		300,000			300,000			1,100,000
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					300,000			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		(700,000)			(700,000)			(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]	600,000			600,000			6,500,000
Long-term Risk Management Assets	[8]	0			0			12,600,000
Total Assets	[8]	600,000			600,000			19,100,000
Current Risk Management Liabilities	[8]	5,300,000			5,300,000			0
Long-term Risk Management Liabilities	[8]	0			0			0
Total Liabilities	[8]	5,300,000			5,300,000			0
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(4,700,000)			(4,700,000)			19,100,000
Interest Rate [Member] | Hedging Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	600,000			600,000
Long-term Risk Management Assets	[8]	0			0
Total Assets	[8]	600,000			600,000
Current Risk Management Liabilities	[8]	5,300,000			5,300,000
Long-term Risk Management Liabilities	[8]	0			0
Total Liabilities	[8]	5,300,000			5,300,000
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(4,700,000)			(4,700,000)
Gross Amounts of Risk Management Assets/Liabilities Recognized [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		278,800,000			278,800,000			531,900,000
Long-term Risk Management Assets		300,800,000			300,800,000			314,400,000
Total Assets		579,600,000			579,600,000			846,300,000
Current Risk Management Liabilities		229,000,000.0			229,000,000.0			496,800,000
Long-term Risk Management Liabilities		296,000,000.0			296,000,000.0			320,200,000
Total Liabilities		525,000,000.0			525,000,000.0			817,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)		54,600,000			54,600,000			29,300,000
Gross Amounts Offset in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(163,600,000)			(163,600,000)			(359,100,000)
Long-term Risk Management Assets	[9]	(57,900,000)			(57,900,000)			(47,800,000)
Total Assets	[9]	(221,500,000)			(221,500,000)			(406,900,000)
Current Risk Management Liabilities	[9]	(166,600,000)			(166,600,000)			(382,500,000)
Long-term Risk Management Liabilities	[9]	(63,600,000)			(63,600,000)			(58,400,000)
Total Liabilities	[9]	(230,200,000)			(230,200,000)			(440,900,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	8,700,000			8,700,000			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]	(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]	100,000			100,000			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]	(19,500,000)			(19,500,000)			(85,000,000.0)
Long-term Risk Management Assets	[9]	(1,500,000)			(1,500,000)			(800,000)
Total Assets	[9]	(21,000,000.0)			(21,000,000.0)			(85,800,000)
Current Risk Management Liabilities	[9]	(20,400,000)			(20,400,000)			(84,300,000)
Long-term Risk Management Liabilities	[9]	(1,600,000)			(1,600,000)			(700,000)
Total Liabilities	[9]	(22,000,000.0)			(22,000,000.0)			(85,000,000.0)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	1,000,000.0			1,000,000.0			(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]	(12,400,000)			(12,400,000)			(57,100,000)
Long-term Risk Management Assets	[9]	(1,000,000.0)			(1,000,000.0)			(400,000)
Total Assets	[9]	(13,400,000)			(13,400,000)			(57,500,000)
Current Risk Management Liabilities	[9]	(12,900,000)			(12,900,000)			(54,700,000)
Long-term Risk Management Liabilities	[9]	(1,000,000.0)			(1,000,000.0)			(400,000)
Total Liabilities	[9]	(13,900,000)			(13,900,000)			(55,100,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	500,000			500,000			(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]	(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]	100,000			100,000			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]	0			0			(500,000)
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	0			0			(500,000)
Current Risk Management Liabilities	[9]	(100,000)			(100,000)			(500,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(100,000)			(100,000)			(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]	0			0			(100,000)
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	0			0			(100,000)
Current Risk Management Liabilities	[9]	(100,000)			(100,000)			(100,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(100,000)			(100,000)			(100,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	100,000			100,000			0
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	115,200,000			115,200,000			172,800,000
Long-term Risk Management Assets	[10]	242,900,000			242,900,000			266,600,000
Total Assets	[10]	358,100,000			358,100,000			439,400,000
Current Risk Management Liabilities	[10]	62,400,000			62,400,000			114,300,000
Long-term Risk Management Liabilities	[10]	232,400,000			232,400,000			261,800,000
Total Liabilities	[10]	294,800,000			294,800,000			376,100,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	63,300,000			63,300,000			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]	30,700,000			30,700,000			39,400,000
Long-term Risk Management Assets	[10]	100,000			100,000			100,000
Total Assets	[10]	30,800,000			30,800,000			39,500,000
Current Risk Management Liabilities	[10]	5,600,000			5,600,000			1,900,000
Long-term Risk Management Liabilities	[10]	200,000			200,000			0
Total Liabilities	[10]	5,800,000			5,800,000			1,900,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	25,000,000.0			25,000,000.0			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]	4,100,000			4,100,000			9,800,000
Long-term Risk Management Assets	[10]	0			0			100,000
Total Assets	[10]	4,100,000			4,100,000			9,900,000
Current Risk Management Liabilities	[10]	200,000			200,000			500,000
Long-term Risk Management Liabilities	[10]	100,000			100,000			0
Total Liabilities	[10]	300,000			300,000			500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	3,800,000			3,800,000			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]	8,200,000			8,200,000			7,300,000
Long-term Risk Management Liabilities	[10]	105,100,000			105,100,000			96,300,000
Total Liabilities	[10]	113,300,000			113,300,000			103,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	(113,300,000)			(113,300,000)			(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]	16,600,000			16,600,000			15,800,000
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	16,600,000			16,600,000			15,800,000
Current Risk Management Liabilities	[10]	500,000			500,000			0
Long-term Risk Management Liabilities	[10]	0			0			0
Total Liabilities	[10]	500,000			500,000			0
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	16,100,000			16,100,000			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]	4,500,000			4,500,000			6,400,000
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	4,500,000			4,500,000			6,400,000
Current Risk Management Liabilities	[10]	100,000			100,000			1,900,000
Long-term Risk Management Liabilities	[10]	700,000			700,000			3,100,000
Total Liabilities	[10]	800,000			800,000			5,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	$ 3,700,000			$ 3,700,000			$ 1,400,000
Power [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		390.6			390.6			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		71.7			71.7			61.0
Power [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		28.9			28.9			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		19.8			19.8			14.9
Power [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		5.6			5.6			4.4
Natural Gas [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		33.3			33.3			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		8.8			8.8			11.6
Heating Oil and Gasoline [Member]
Commodity:
Derivative, Volume Notional Amount | gal		8.3			8.3			6.9
Heating Oil and Gasoline [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Volume Notional Amount | gal		2.2			2.2			1.8
Heating Oil and Gasoline [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.3			1.3			1.1
Heating Oil and Gasoline [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.8			0.8			0.6
Heating Oil and Gasoline [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.7			1.7			1.4
Heating Oil and Gasoline [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.9			0.9			0.7
Heating Oil and Gasoline [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.1			1.1			0.9
Interest Rate Contract [Member]
Commodity:
Derivative, Notional Amount		$ 129,800,000			$ 129,800,000			$ 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		500,000		500,000	800,000		1,000,000.0
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		11,500,000		21,000,000.0	11,100,000		27,200,000
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		300,000		200,000	400,000		200,000
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		200,000	100,000		500,000
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		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		300,000		400,000	1,200,000		1,600,000
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		200,000		300,000	1,000,000.0		1,400,000
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		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		(400,000)		(100,000)	(1,400,000)		(600,000)
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		(100,000)		0	(400,000)		(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)	(200,000)		(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)	(200,000)		(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)	(300,000)		(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)	(200,000)		(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)		0	(200,000)		(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)		(200,000)	(2,200,000)		(600,000)
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		(200,000)		0	(600,000)		(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)		0	(300,000)		(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)		(100,000)	(200,000)		(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		(200,000)		0	(400,000)		(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		0		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		(100,000)		0	(300,000)		(100,000)
Regulatory Assets [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	7,900,000		(4,800,000)	(8,500,000)		(19,400,000)
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]	200,000		(200,000)	(300,000)		300,000
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]	400,000		200,000	(100,000)		400,000
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]	200,000		0	(200,000)		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]	4,400,000		(2,600,000)	(9,900,000)		(19,800,000)
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]	(400,000)		(100,000)	(600,000)		900,000
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]	2,900,000		(1,600,000)	2,200,000		(400,000)
Regulatory Liabilities [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	17,000,000.0		26,300,000	80,900,000		64,500,000
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]	3,800,000		10,000,000.0	16,200,000		(5,300,000)
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]	2,600,000		3,200,000	8,800,000		17,200,000
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]	1,700,000		0	8,400,000		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]	3,100,000		4,300,000	23,900,000		26,600,000
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]	$ 2,000,000.0		$ 4,500,000	$ 14,800,000		$ 22,900,000

[1] Amounts include $(55) million and $0 as of September 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 September 30, 2020 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 2 matures $(6) million in 2020, $3 million in periods 2021-2023, $4 million in periods 2024-2025 and $7 million in periods 2026-2033; Level 3 matures $35 million in 2020, $63 million in periods 2021-2023, $21 million in periods 2024-2025 and $(12) million in periods 2026-2033.  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.