Derivatives and Hedging (Details) gal in Millions, MWh in Millions, MMBTU in Millions		3 Months Ended			6 Months Ended			12 Months Ended
		Jun. 30, 2019 USD ($) MWh MMBTU gal		Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) MWh MMBTU gal		Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) MWh MMBTU gal
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		$ 3,500,000			$ 3,500,000			$ 18,000,000.0
Cash Collateral Paid Netted Against Risk Management Liabilities		31,500,000			31,500,000			4,200,000
Fair Value of Derivative Instruments
Current Risk Management Assets		249,600,000			249,600,000			162,800,000
Long-term Risk Management Assets		313,500,000			313,500,000			254,000,000.0
Total Assets		563,100,000			563,100,000			416,800,000
Current Risk Management Liabilities		141,400,000			141,400,000			55,000,000.0
Long-term Risk Management Liabilities		348,500,000			348,500,000			263,400,000
Total Liabilities		489,900,000			489,900,000			318,400,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		55,500,000		$ 119,700,000	30,600,000		$ 229,000,000.0
Carrying Amount of Hedged Asset (Liability)	[1]	(507,900,000)			(507,900,000)			(478,300,000)
Cumulative Fair Value Hedging Adjustment in the Carrying Amount of the Hedged Asset (Liability)	[1]	(11,900,000)			(11,900,000)			17,400,000
Gain (Loss) on Hedging Instruments
Gain (Loss) on Fair Value Hedging Instruments	[2]	18,200,000		(7,300,000)	29,300,000		(21,800,000)
Gain (Loss) on Fair Value Portion of Long Term Debt	[2]	(18,200,000)		7,300,000	(29,300,000)		21,800,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		347,000,000.0			347,000,000.0			225,500,000
Amount of Cash Collateral Posted		6,700,000			6,700,000			1,800,000
Additional Settlement Liability if Cross Default Provision is Triggered		317,800,000			317,800,000			181,000,000.0
AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Liabilities		200,000			200,000			200,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(100,000)		300,000	300,000		400,000
Appalachian Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		900,000			900,000			1,500,000
Cash Collateral Paid Netted Against Risk Management Liabilities		3,400,000			3,400,000			600,000
Fair Value of Derivative Instruments
Current Risk Management Assets		74,700,000			74,700,000			57,200,000
Long-term Risk Management Assets		400,000			400,000			900,000
Current Risk Management Liabilities		4,600,000			4,600,000			400,000
Long-term Risk Management Liabilities		100,000			100,000			200,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		19,900,000		41,300,000	(14,100,000)		109,800,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		6,100,000			6,100,000			900,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		500,000			500,000			0
Indiana Michigan Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		800,000			800,000			1,600,000
Cash Collateral Paid Netted Against Risk Management Liabilities		2,100,000			2,100,000			700,000
Fair Value of Derivative Instruments
Current Risk Management Assets		15,700,000			15,700,000			8,600,000
Long-term Risk Management Assets		300,000			300,000			600,000
Current Risk Management Liabilities		1,200,000			1,200,000			300,000
Long-term Risk Management Liabilities		0			0			100,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		7,400,000		6,700,000	14,600,000		8,200,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		3,600,000			3,600,000			500,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		300,000			300,000			0
Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Liabilities		7,600,000			7,600,000			5,800,000
Long-term Risk Management Liabilities		104,100,000			104,100,000			93,800,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(8,300,000)		10,500,000	(17,400,000)		42,100,000
Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		28,000,000.0			28,000,000.0			10,400,000
Current Risk Management Liabilities		300,000			300,000			1,000,000.0
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		16,600,000		19,000,000.0	23,300,000		31,100,000
Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		12,300,000			12,300,000			4,800,000
Current Risk Management Liabilities		1,500,000			1,500,000			400,000
Long-term Risk Management Liabilities		2,400,000			2,400,000			2,200,000
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		14,900,000		6,400,000	19,500,000		5,300,000
Collateral Triggering Events [Abstract]
Fair Value Of Derivative Liabilities Subject To Cross Default Provisions		4,000,000.0			4,000,000.0			2,300,000
Amount of Cash Collateral Posted		0			0			0
Additional Settlement Liability if Cross Default Provision is Triggered		2,900,000			2,900,000			2,300,000
Risk Management Contracts [Member]
Fair Value of Derivative Instruments
Total Assets	[3]	535,500,000	[4]		535,500,000	[4]		382,700,000	[5]
Total Liabilities	[3]	322,000,000.0	[4]		322,000,000.0	[4]		242,100,000	[5]
Risk Management Contracts [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Total Liabilities	[3]	200,000			200,000			200,000
Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[3],[6]	75,100,000			75,100,000			58,100,000
Total Liabilities	[3],[6]	4,700,000			4,700,000			600,000
Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[3],[6]	16,000,000.0			16,000,000.0			9,200,000
Total Liabilities	[3],[6]	1,200,000			1,200,000			400,000
Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Total Liabilities	[3],[6]	111,700,000			111,700,000			99,600,000
Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Total Assets	[3],[6]	28,000,000.0			28,000,000.0			10,400,000
Total Liabilities	[3],[6]	300,000			300,000			1,000,000.0
Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[3],[6]	12,300,000			12,300,000			4,800,000
Total Liabilities	[3],[6]	3,900,000			3,900,000			2,600,000
Commodity [Member]
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(127,200,000)			(127,200,000)			(23,000,000.0)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ (45,400,000)			10,400,000
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	[7]	534,300,000			534,300,000			397,500,000
Long-term Risk Management Assets	[7]	358,700,000			358,700,000			276,400,000
Total Assets	[7]	893,000,000.0			893,000,000.0			673,900,000
Current Risk Management Liabilities	[7]	384,700,000			384,700,000			293,800,000
Long-term Risk Management Liabilities	[7]	322,800,000			322,800,000			225,700,000
Total Liabilities	[7]	707,500,000			707,500,000			519,500,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	185,500,000			185,500,000			154,400,000
Commodity [Member] | Risk Management Contracts [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	0			0			0
Long-term Risk Management Assets	[7]	0			0			0
Total Assets	[7]	0			0			0
Current Risk Management Liabilities	[7]	200,000			200,000			700,000
Long-term Risk Management Liabilities	[7]	0			0			0
Total Liabilities	[7]	200,000			200,000			700,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	(200,000)			(200,000)			(700,000)
Commodity [Member] | Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	138,100,000			138,100,000			114,400,000
Long-term Risk Management Assets	[7]	7,300,000			7,300,000			3,100,000
Total Assets	[7]	145,400,000			145,400,000			117,500,000
Current Risk Management Liabilities	[7]	70,400,000			70,400,000			56,700,000
Long-term Risk Management Liabilities	[7]	7,100,000			7,100,000			2,400,000
Total Liabilities	[7]	77,500,000			77,500,000			59,100,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	67,900,000			67,900,000			58,400,000
Commodity [Member] | Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	55,100,000			55,100,000			50,400,000
Long-term Risk Management Assets	[7]	4,500,000			4,500,000			2,000,000.0
Total Assets	[7]	59,600,000			59,600,000			52,400,000
Current Risk Management Liabilities	[7]	41,800,000			41,800,000			41,100,000
Long-term Risk Management Liabilities	[7]	4,300,000			4,300,000			1,600,000
Total Liabilities	[7]	46,100,000			46,100,000			42,700,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	13,500,000			13,500,000			9,700,000
Commodity [Member] | Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	0			0			0
Long-term Risk Management Assets	[7]	0			0			0
Total Assets	[7]	0			0			0
Current Risk Management Liabilities	[7]	7,600,000			7,600,000			6,400,000
Long-term Risk Management Liabilities	[7]	104,100,000			104,100,000			93,800,000
Total Liabilities	[7]	111,700,000			111,700,000			100,200,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	(111,700,000)			(111,700,000)			(100,200,000)
Commodity [Member] | Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	28,400,000			28,400,000			10,900,000
Long-term Risk Management Assets	[7]	0			0			0
Total Assets	[7]	28,400,000			28,400,000			10,900,000
Current Risk Management Liabilities	[7]	700,000			700,000			1,700,000
Long-term Risk Management Liabilities	[7]	0			0			0
Total Liabilities	[7]	700,000			700,000			1,700,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	27,700,000			27,700,000			9,200,000
Commodity [Member] | Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	12,500,000			12,500,000			5,600,000
Long-term Risk Management Assets	[7]	0			0			0
Total Assets	[7]	12,500,000			12,500,000			5,600,000
Current Risk Management Liabilities	[7]	1,700,000			1,700,000			1,500,000
Long-term Risk Management Liabilities	[7]	2,400,000			2,400,000			2,200,000
Total Liabilities	[7]	4,100,000			4,100,000			3,700,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	8,400,000			8,400,000			1,900,000
Commodity [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	4,800,000			4,800,000			28,500,000
Long-term Risk Management Assets	[7]	4,200,000			4,200,000			16,000,000.0
Total Assets	[7]	9,000,000.0			9,000,000.0			44,500,000
Current Risk Management Liabilities	[7]	55,500,000			55,500,000			13,200,000
Long-term Risk Management Liabilities	[7]	105,700,000			105,700,000			56,100,000
Total Liabilities	[7]	161,200,000			161,200,000			69,300,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	(152,200,000)			(152,200,000)			(24,800,000)
Interest Rate [Member]
Commodity:
Derivative, Notional Amount		500,000,000.0			500,000,000.0			500,000,000.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(15,900,000)	[8]		(15,900,000)	[8]		(12,600,000)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					$ (2,200,000)			(1,100,000)
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows					138 months
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		(3,900,000)			(3,900,000)			(4,400,000)
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		0			0			0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		1,400,000			1,400,000			1,800,000
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		(10,700,000)			(10,700,000)			(11,500,000)
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
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		300,000			300,000			1,000,000.0
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					300,000			1,000,000.0
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		1,600,000			1,600,000			2,100,000
Portion Expected to be Reclassified to Net Income During the Next Twelve Months					1,000,000.0			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		(2,500,000)			(2,500,000)			(3,300,000)
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	[7]	200,000			200,000			0
Long-term Risk Management Assets	[7]	11,700,000			11,700,000			0
Total Assets	[7]	11,900,000			11,900,000			0
Current Risk Management Liabilities	[7]	0			0			2,000,000.0
Long-term Risk Management Liabilities	[7]	0			0			15,400,000
Total Liabilities	[7]	0			0			17,400,000
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	11,900,000			11,900,000			(17,400,000)
Gross Amounts of Risk Management Assets/Liabilities Recognized [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		539,300,000			539,300,000			426,000,000.0
Long-term Risk Management Assets		374,600,000			374,600,000			292,400,000
Total Assets		913,900,000			913,900,000			718,400,000
Current Risk Management Liabilities		440,200,000			440,200,000			309,000,000.0
Long-term Risk Management Liabilities		428,500,000			428,500,000			297,200,000
Total Liabilities		868,700,000			868,700,000			606,200,000
Total MTM Derivative Contract Net Assets (Liabilities)		45,200,000			45,200,000			112,200,000
Gross Amounts Offset in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(289,700,000)			(289,700,000)			(263,200,000)
Long-term Risk Management Assets	[9]	(61,100,000)			(61,100,000)			(38,400,000)
Total Assets	[9]	(350,800,000)			(350,800,000)			(301,600,000)
Current Risk Management Liabilities	[9]	(298,800,000)			(298,800,000)			(254,000,000.0)
Long-term Risk Management Liabilities	[9]	(80,000,000.0)			(80,000,000.0)			(33,800,000)
Total Liabilities	[9]	(378,800,000)			(378,800,000)			(287,800,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	28,000,000.0			28,000,000.0			(13,800,000)
Gross Amounts Offset in the Statement of Financial Position [Member] | AEP Texas Inc. [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	0			0			0
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	0			0			0
Current Risk Management Liabilities	[9]	0			0			(500,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	0			0			(500,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	0			0			500,000
Gross Amounts Offset in the Statement of Financial Position [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(63,400,000)			(63,400,000)			(57,200,000)
Long-term Risk Management Assets	[9]	(6,900,000)			(6,900,000)			(2,200,000)
Total Assets	[9]	(70,300,000)			(70,300,000)			(59,400,000)
Current Risk Management Liabilities	[9]	(65,800,000)			(65,800,000)			(56,300,000)
Long-term Risk Management Liabilities	[9]	(7,000,000.0)			(7,000,000.0)			(2,200,000)
Total Liabilities	[9]	(72,800,000)			(72,800,000)			(58,500,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	2,500,000			2,500,000			(900,000)
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]	(39,400,000)			(39,400,000)			(41,800,000)
Long-term Risk Management Assets	[9]	(4,200,000)			(4,200,000)			(1,400,000)
Total Assets	[9]	(43,600,000)			(43,600,000)			(43,200,000)
Current Risk Management Liabilities	[9]	(40,600,000)			(40,600,000)			(40,800,000)
Long-term Risk Management Liabilities	[9]	(4,300,000)			(4,300,000)			(1,500,000)
Total Liabilities	[9]	(44,900,000)			(44,900,000)			(42,300,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	1,300,000			1,300,000			(900,000)
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]	0			0			(600,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	0			0			(600,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	0			0			600,000
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]	(400,000)			(400,000)			(500,000)
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	(400,000)			(400,000)			(500,000)
Current Risk Management Liabilities	[9]	(400,000)			(400,000)			(700,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(400,000)			(400,000)			(700,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	0			0			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]	(200,000)			(200,000)			(800,000)
Long-term Risk Management Assets	[9]	0			0			0
Total Assets	[9]	(200,000)			(200,000)			(800,000)
Current Risk Management Liabilities	[9]	(200,000)			(200,000)			(1,100,000)
Long-term Risk Management Liabilities	[9]	0			0			0
Total Liabilities	[9]	(200,000)			(200,000)			(1,100,000)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	0			0			300,000
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	249,600,000			249,600,000			162,800,000
Long-term Risk Management Assets	[10]	313,500,000			313,500,000			254,000,000.0
Total Assets	[10]	563,100,000			563,100,000			416,800,000
Current Risk Management Liabilities	[10]	141,400,000			141,400,000			55,000,000.0
Long-term Risk Management Liabilities	[10]	348,500,000			348,500,000			263,400,000
Total Liabilities	[10]	489,900,000			489,900,000			318,400,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	73,200,000			73,200,000			98,400,000
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]	200,000			200,000			200,000
Long-term Risk Management Liabilities	[10]	0			0			0
Total Liabilities	[10]	200,000			200,000			200,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	(200,000)			(200,000)			(200,000)
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]	74,700,000			74,700,000			57,200,000
Long-term Risk Management Assets	[10]	400,000			400,000			900,000
Total Assets	[10]	75,100,000			75,100,000			58,100,000
Current Risk Management Liabilities	[10]	4,600,000			4,600,000			400,000
Long-term Risk Management Liabilities	[10]	100,000			100,000			200,000
Total Liabilities	[10]	4,700,000			4,700,000			600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	70,400,000			70,400,000			57,500,000
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]	15,700,000			15,700,000			8,600,000
Long-term Risk Management Assets	[10]	300,000			300,000			600,000
Total Assets	[10]	16,000,000.0			16,000,000.0			9,200,000
Current Risk Management Liabilities	[10]	1,200,000			1,200,000			300,000
Long-term Risk Management Liabilities	[10]	0			0			100,000
Total Liabilities	[10]	1,200,000			1,200,000			400,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	14,800,000			14,800,000			8,800,000
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]	7,600,000			7,600,000			5,800,000
Long-term Risk Management Liabilities	[10]	104,100,000			104,100,000			93,800,000
Total Liabilities	[10]	111,700,000			111,700,000			99,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	(111,700,000)			(111,700,000)			(99,600,000)
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]	28,000,000.0			28,000,000.0			10,400,000
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	28,000,000.0			28,000,000.0			10,400,000
Current Risk Management Liabilities	[10]	300,000			300,000			1,000,000.0
Long-term Risk Management Liabilities	[10]	0			0			0
Total Liabilities	[10]	300,000			300,000			1,000,000.0
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	27,700,000			27,700,000			9,400,000
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]	12,300,000			12,300,000			4,800,000
Long-term Risk Management Assets	[10]	0			0			0
Total Assets	[10]	12,300,000			12,300,000			4,800,000
Current Risk Management Liabilities	[10]	1,500,000			1,500,000			400,000
Long-term Risk Management Liabilities	[10]	2,400,000			2,400,000			2,200,000
Total Liabilities	[10]	3,900,000			3,900,000			2,600,000
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	$ 8,400,000			$ 8,400,000			$ 2,200,000
Power [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		478.4			478.4			371.1
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		125.6			125.6			66.4
Power [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		45.1			45.1			40.9
Power [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		7.4			7.4			7.8
Power [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		31.0			31.0			15.2
Power [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		9.8			9.8			4.5
Natural Gas [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		64.5			64.5			87.9
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			4.0
Natural Gas [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.0			0.0			2.3
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		13.4			13.4			15.2
Heating Oil and Gasoline [Member]
Commodity:
Derivative, Volume Notional Amount | gal		7.9			7.9			7.4
Heating Oil and Gasoline [Member] | AEP Texas Inc. [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.6			1.6			1.5
Heating Oil and Gasoline [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.5			1.5			1.4
Heating Oil and Gasoline [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.7			0.7			0.7
Heating Oil and Gasoline [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.9			1.9			1.8
Heating Oil and Gasoline [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.8			0.8			0.7
Heating Oil and Gasoline [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.9			0.9			0.8
Interest Rate Contract [Member]
Commodity:
Derivative, Notional Amount		$ 143,900,000			$ 143,900,000			$ 37,700,000
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		200,000		(3,200,000)	500,000		(8,700,000)
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		3,500,000		27,500,000	6,200,000		12,400,000
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		(500,000)	0		(800,000)
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		(2,600,000)	300,000		(7,700,000)
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	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		(200,000)		3,100,000	1,200,000		8,000,000.0
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		1,100,000		2,400,000	1,100,000		7,000,000.0
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		600,000	100,000		800,000
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		(100,000)		500,000	(500,000)		800,000
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		0		100,000	(100,000)		200,000
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	0		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		0		100,000	0		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		0		100,000	(100,000)		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		0		100,000	0		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		100,000		500,000	(400,000)		900,000
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		0		100,000	(100,000)		200,000
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	(100,000)		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	0		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		0		100,000	(100,000)		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		100,000	0		100,000
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		0		100,000	(100,000)		100,000
Regulatory Assets [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	(8,200,000)		5,900,000	(14,600,000)		43,200,000
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]	(100,000)		0	500,000		0
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]	2,300,000		0	200,000		0
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]	(100,000)		(3,000,000.0)	200,000		3,200,000
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]	(8,300,000)		9,700,000	(17,200,000)		41,100,000
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]	500,000		0	1,000,000.0		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		(800,000)	1,200,000		(1,100,000)
Regulatory Liabilities [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[11]	60,200,000		85,400,000	38,200,000		172,400,000
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		100,000	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]	16,400,000		39,200,000	(15,300,000)		103,300,000
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]	7,400,000		11,500,000	14,000,000.0		11,700,000
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]	0		600,000	0		600,000
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]	16,100,000		18,800,000	22,300,000		30,900,000
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]	$ 13,700,000		$ 6,900,000	$ 18,400,000		$ 6,100,000

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

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

[3] 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.’’

[4] The June 30, 2019 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 2 matures $(10) million in 2019 and $(10) million in periods 2020-2022, $2 million in periods 2023-2024 and $1 million in periods 2025-2032; Level 3 matures $86 million in 2019, $106 million in periods 2020-2022, $23 million in periods 2023-2024 and $(12) million in periods 2025-2032.  Risk management commodity contracts are substantially comprised of power contracts.

[5] The December 31, 2018 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 2 matures $(4) million in 2019, $1 million in periods 2020-2022, $1 million in periods 2023-2024 and $1 million in periods 2025-2032; Level 3 matures $108 million in 2019, $37 million in periods 2020-2022, $23 million in periods 2023-2024 and $(12) million in periods 2025-2032.  Risk management commodity contracts are substantially comprised of power contracts.

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

[7] 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.”

[8] Includes $4 million related to AEP's investment in joint venture wind farms acquired as part of the purchase of Sempra Renewables LLC. See “Sempra Renewables LLC” section of Note 14 for additional information.

[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.