Derivatives and Hedging (Details) gal in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions		3 Months Ended			12 Months Ended
		Mar. 31, 2016 USD ($) MWh MMBTU T gal		Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) MWh MMBTU T gal
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		$ 11.8			$ 5.8
Cash Collateral Paid Netted Against Risk Management Liabilities		43.0			44.4
Fair Value of Derivative Instruments
Current Risk Management Assets		143.8			134.4
Long-term Risk Management Assets		328.9			321.8
Total Assets		472.7			456.2
Current Risk Management Liabilities		104.3			87.1
Long-term Risk Management Liabilities		207.6			179.1
Derivative Liability		311.9			266.2
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		19.1		$ 54.6
Gain (Loss) on Hedging Instruments
Gain (Loss) on Fair Value Hedging Instruments		3.5		4.5
Gain (Loss) on Fair Value Portion of Long-term Debt		(3.5)		(4.5)
Collateral Triggering Events [Abstract]
Amount of Collateral AEP Subsidiaries Would Have Been Required to Post Attributable to RTOs and ISOs		23.6			17.5
Amount Attributable to Other Contracts	[1]	298.3			297.8
Liabilities for Contracts with Cross Default Provisions Prior to Contractual Netting Arrangements		328.8			300.1
Amount of Cash Collateral Posted		0.0			0.8
Additional Settlement Liability if Cross Default Provision is Triggered		$ 276.2			240.6
Derivatives and Hedging (Textuals) [Abstract]
Maximum Term for Exposure to Variability of Future Cash Flows		141 months
Appalachian Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		$ 0.0			0.0
Cash Collateral Paid Netted Against Risk Management Liabilities		0.6			3.1
Fair Value of Derivative Instruments
Current Risk Management Assets		11.2			14.7
Long-term Risk Management Assets		0.3			0.1
Current Risk Management Liabilities		10.4			4.8
Long-term Risk Management Liabilities		0.1			0.1
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		17.5		3.4
Collateral Triggering Events [Abstract]
Amount of Collateral AEP Subsidiaries Would Have Been Required to Post Attributable to RTOs and ISOs		2.2			4.9
Amount Attributable to Other Contracts		0.1			0.1
Liabilities for Contracts with Cross Default Provisions Prior to Contractual Netting Arrangements		3.8			3.7
Amount of Cash Collateral Posted		0.0			0.0
Additional Settlement Liability if Cross Default Provision is Triggered		3.8			3.7
Indiana Michigan Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		0.0			0.0
Cash Collateral Paid Netted Against Risk Management Liabilities		0.1			0.6
Fair Value of Derivative Instruments
Current Risk Management Assets		8.4			10.6
Long-term Risk Management Assets		0.4			0.0
Current Risk Management Liabilities		6.4			6.3
Long-term Risk Management Liabilities		1.0			1.6
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		9.7		(1.2)
Collateral Triggering Events [Abstract]
Amount of Collateral AEP Subsidiaries Would Have Been Required to Post Attributable to RTOs and ISOs		1.4			3.3
Amount Attributable to Other Contracts		0.0			0.1
Liabilities for Contracts with Cross Default Provisions Prior to Contractual Netting Arrangements		2.6			2.5
Amount of Cash Collateral Posted		0.0			0.0
Additional Settlement Liability if Cross Default Provision is Triggered		2.6			2.5
Ohio Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		0.0			0.0
Cash Collateral Paid Netted Against Risk Management Liabilities		0.2			0.5
Fair Value of Derivative Instruments
Long-term Risk Management Assets		0.0			19.2
Current Risk Management Liabilities		5.5			3.6
Long-term Risk Management Liabilities		5.8			0.0
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(30.3)		4.4
Public Service Co Of Oklahoma [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		0.0			0.0
Cash Collateral Paid Netted Against Risk Management Liabilities		0.1			0.3
Fair Value of Derivative Instruments
Current Risk Management Assets		0.7			0.6
Current Risk Management Liabilities		0.2			0.2
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(0.7)		(1.0)
Collateral Triggering Events [Abstract]
Amount of Collateral AEP Subsidiaries Would Have Been Required to Post Attributable to RTOs and ISOs		2.1			0.0
Amount Attributable to Other Contracts		3.2			3.2
Southwestern Electric Power Co [Member]
Cash Collateral Netting
Cash Collateral Received Netted Against Risk Management Assets		0.0			0.0
Cash Collateral Paid Netted Against Risk Management Liabilities		0.2			0.3
Fair Value of Derivative Instruments
Current Risk Management Assets		0.8			0.8
Current Risk Management Liabilities		3.5			3.1
Long-term Risk Management Liabilities		1.8			2.1
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		4.4		0.2
Collateral Triggering Events [Abstract]
Amount of Collateral AEP Subsidiaries Would Have Been Required to Post Attributable to RTOs and ISOs		2.7			0.0
Amount Attributable to Other Contracts		0.1			0.1
Risk Management Contracts [Member]
Fair Value of Derivative Instruments
Total Assets	[2]	452.0	[3]		438.5	[4]
Derivative Liability	[2]	271.0	[3]		236.6	[4]
Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[2],[5]	12.2			15.7
Derivative Liability	[2],[5]	10.5			4.9
Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[2],[5]	9.5			12.3
Derivative Liability	[2],[5]	7.4			7.9
Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[2],[5]				19.2
Derivative Liability	[2],[5]	11.3			3.6
Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Total Assets	[2],[5]	0.7			0.6
Derivative Liability	[2],[5]	0.2			0.2
Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Total Assets	[2],[5]	0.8			0.8
Derivative Liability	[2],[5]	5.3			5.2
Commodity [Member]
Impact of Cash Flow Hedges on the Condensed Balance Sheet
Hedging Assets	[6]	19.8			17.6
Hedging Liabilities	[6]	40.1			26.1
AOCI Gain (Loss) Net of Tax		(12.9)			(5.2)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months		(1.7)			(0.4)
Derivatives and Hedging (Textuals) [Abstract]
Cross Default Provisions Maximum Third Party Obligation Amount		50.0			50.0
Commodity [Member] | Risk Management Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	425.9			368.8
Long-term Risk Management Assets	[7]	390.1			364.8
Total Assets	[7]	816.0			733.6
Current Risk Management Liabilities	[7]	401.6			347.0
Long-term Risk Management Liabilities	[7]	264.6			223.3
Derivative Liability	[7]	666.2			570.3
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	149.8			163.3
Commodity [Member] | Risk Management Contracts [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	24.1			25.9
Long-term Risk Management Assets	[8]	1.0			0.3
Total Assets	[8]	25.1			26.2
Current Risk Management Liabilities	[8]	23.2			18.1
Long-term Risk Management Liabilities	[8]	0.8			0.3
Derivative Liability	[8]	24.0			18.4
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	1.1			7.8
Commodity [Member] | Risk Management Contracts [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	17.6			22.8
Long-term Risk Management Assets	[8]	0.9			0.6
Total Assets	[8]	18.5			23.4
Current Risk Management Liabilities	[8]	15.0			17.0
Long-term Risk Management Liabilities	[8]	1.5			2.6
Derivative Liability	[8]	16.5			19.6
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	2.0			3.8
Commodity [Member] | Risk Management Contracts [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	0.0			0.0
Long-term Risk Management Assets	[8]	0.0			19.2
Total Assets	[8]	0.0			19.2
Current Risk Management Liabilities	[8]	5.7			4.1
Long-term Risk Management Liabilities	[8]	5.8			0.0
Derivative Liability	[8]	11.5			4.1
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(11.5)			15.1
Commodity [Member] | Risk Management Contracts [Member] | Public Service Co Of Oklahoma [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	0.7			0.6
Long-term Risk Management Assets	[8]	0.0			0.0
Total Assets	[8]	0.7			0.6
Current Risk Management Liabilities	[8]	0.3			0.5
Long-term Risk Management Liabilities	[8]	0.0			0.0
Derivative Liability	[8]	0.3			0.5
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	0.4			0.1
Commodity [Member] | Risk Management Contracts [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[8]	0.9			0.8
Long-term Risk Management Assets	[8]	0.0			0.0
Total Assets	[8]	0.9			0.8
Current Risk Management Liabilities	[8]	3.8			3.4
Long-term Risk Management Liabilities	[8]	1.8			2.1
Derivative Liability	[8]	5.6			5.5
Total MTM Derivative Contract Net Assets (Liabilities)	[8]	(4.7)			(4.7)
Commodity [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	9.8			8.2
Long-term Risk Management Assets	[7]	13.5			11.7
Total Assets	[7]	23.3			19.9
Current Risk Management Liabilities	[7]	12.6			9.1
Long-term Risk Management Liabilities	[7]	31.0			19.3
Derivative Liability	[7]	43.6			28.4
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	(20.3)			(8.5)
Interest Rate and Foreign Currency [Member]
Commodity:
Derivative, Notional Amount		559.3			560.3
Impact of Cash Flow Hedges on the Condensed Balance Sheet
Hedging Assets	[6]	0.0			0.0
Hedging Liabilities	[6]	0.4			0.4
AOCI Gain (Loss) Net of Tax		(16.9)			(17.2)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months		(1.4)			(1.5)
Interest Rate and Foreign Currency [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Notional Amount		0.0			0.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		3.4			3.6
Portion Expected to be Reclassified to Net Income During the Next Twelve Months		0.7			0.7
Interest Rate and Foreign Currency [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Notional Amount		0.0			0.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(12.9)			(13.3)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months		(1.3)			(1.3)
Interest Rate and Foreign Currency [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Notional Amount		0.0			0.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		3.9			4.3
Portion Expected to be Reclassified to Net Income During the Next Twelve Months		1.1			1.2
Interest Rate and Foreign Currency [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Notional Amount		0.0			0.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		4.0			4.2
Portion Expected to be Reclassified to Net Income During the Next Twelve Months		0.8			0.8
Interest Rate and Foreign Currency [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Notional Amount		0.0			0.0
Impact of Cash Flow Hedges on the Condensed Balance Sheet
AOCI Gain (Loss) Net of Tax		(8.6)			(9.1)
Portion Expected to be Reclassified to Net Income During the Next Twelve Months		(1.7)			(1.7)
Interest Rate and Foreign Currency [Member] | Hedging Contracts [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[7]	0.9			0.1
Long-term Risk Management Assets	[7]	0.0			0.0
Total Assets	[7]	0.9			0.1
Current Risk Management Liabilities	[7]	0.3			0.3
Long-term Risk Management Liabilities	[7]	0.5			3.2
Derivative Liability	[7]	0.8			3.5
Total MTM Derivative Contract Net Assets (Liabilities)	[7]	0.1			(3.4)
Gross Amounts of Risk Management Assets/Liabilities Recognized [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets		436.6			377.1
Long-term Risk Management Assets		403.6			376.5
Total Assets		840.2			753.6
Current Risk Management Liabilities		414.5			356.4
Long-term Risk Management Liabilities		296.1			245.8
Derivative Liability		710.6			602.2
Total MTM Derivative Contract Net Assets (Liabilities)		129.6			151.4
Gross Amounts Offset in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[9]	(292.8)			(242.7)
Long-term Risk Management Assets	[9]	(74.7)			(54.7)
Total Assets	[9]	(367.5)			(297.4)
Current Risk Management Liabilities	[9]	(310.2)			(269.3)
Long-term Risk Management Liabilities	[9]	(88.5)			(66.7)
Derivative Liability	[9]	(398.7)			(336.0)
Total MTM Derivative Contract Net Assets (Liabilities)	[9]	31.2			38.6
Gross Amounts Offset in the Statement of Financial Position [Member] | Appalachian Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	(12.2)			(10.3)
Long-term Risk Management Assets	[10]	(0.7)			(0.2)
Total Assets	[10]	(12.9)			(10.5)
Current Risk Management Liabilities	[10]	(12.8)			(13.3)
Long-term Risk Management Liabilities	[10]	(0.7)			(0.2)
Derivative Liability	[10]	(13.5)			(13.5)
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	0.6			3.0
Gross Amounts Offset in the Statement of Financial Position [Member] | Indiana Michigan Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	(8.5)			(10.5)
Long-term Risk Management Assets	[10]	(0.5)			(0.6)
Total Assets	[10]	(9.0)			(11.1)
Current Risk Management Liabilities	[10]	(8.6)			(10.7)
Long-term Risk Management Liabilities	[10]	(0.5)			(1.0)
Derivative Liability	[10]	(9.1)			(11.7)
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	0.1			0.6
Gross Amounts Offset in the Statement of Financial Position [Member] | Ohio Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	0.0			0.0
Long-term Risk Management Assets	[10]	0.0			0.0
Total Assets	[10]	0.0			0.0
Current Risk Management Liabilities	[10]	(0.2)			(0.5)
Long-term Risk Management Liabilities	[10]	0.0			0.0
Derivative Liability	[10]	(0.2)			(0.5)
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	0.2			0.5
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	[10]	0.0			0.0
Long-term Risk Management Assets	[10]	0.0			0.0
Total Assets	[10]	0.0			0.0
Current Risk Management Liabilities	[10]	(0.1)			(0.3)
Long-term Risk Management Liabilities	[10]	0.0			0.0
Derivative Liability	[10]	(0.1)			(0.3)
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	0.1			0.3
Gross Amounts Offset in the Statement of Financial Position [Member] | Southwestern Electric Power Co [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[10]	(0.1)			0.0
Long-term Risk Management Assets	[10]	0.0			0.0
Total Assets	[10]	(0.1)			0.0
Current Risk Management Liabilities	[10]	(0.3)			(0.3)
Long-term Risk Management Liabilities	[10]	0.0			0.0
Derivative Liability	[10]	(0.3)			(0.3)
Total MTM Derivative Contract Net Assets (Liabilities)	[10]	0.2			0.3
Net Amounts of Assets/Liabilities Presented in the Statement of Financial Position [Member]
Fair Value of Derivative Instruments
Current Risk Management Assets	[11]	143.8			134.4
Long-term Risk Management Assets	[11]	328.9			321.8
Total Assets	[11]	472.7			456.2
Current Risk Management Liabilities	[11]	104.3			87.1
Long-term Risk Management Liabilities	[11]	207.6			179.1
Derivative Liability	[11]	311.9			266.2
Total MTM Derivative Contract Net Assets (Liabilities)	[11]	160.8			190.0
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	[12]	11.9			15.6
Long-term Risk Management Assets	[12]	0.3			0.1
Total Assets	[12]	12.2			15.7
Current Risk Management Liabilities	[12]	10.4			4.8
Long-term Risk Management Liabilities	[12]	0.1			0.1
Derivative Liability	[12]	10.5			4.9
Total MTM Derivative Contract Net Assets (Liabilities)	[12]	1.7			10.8
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	[12]	9.1			12.3
Long-term Risk Management Assets	[12]	0.4			0.0
Total Assets	[12]	9.5			12.3
Current Risk Management Liabilities	[12]	6.4			6.3
Long-term Risk Management Liabilities	[12]	1.0			1.6
Derivative Liability	[12]	7.4			7.9
Total MTM Derivative Contract Net Assets (Liabilities)	[12]	2.1			4.4
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	[12]	0.0			0.0
Long-term Risk Management Assets	[12]	0.0			19.2
Total Assets	[12]	0.0			19.2
Current Risk Management Liabilities	[12]	5.5			3.6
Long-term Risk Management Liabilities	[12]	5.8			0.0
Derivative Liability	[12]	11.3			3.6
Total MTM Derivative Contract Net Assets (Liabilities)	[12]	(11.3)			15.6
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	[12]	0.7			0.6
Long-term Risk Management Assets	[12]	0.0			0.0
Total Assets	[12]	0.7			0.6
Current Risk Management Liabilities	[12]	0.2			0.2
Long-term Risk Management Liabilities	[12]	0.0			0.0
Derivative Liability	[12]	0.2			0.2
Total MTM Derivative Contract Net Assets (Liabilities)	[12]	0.5			0.4
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	[12]	0.8			0.8
Long-term Risk Management Assets	[12]	0.0			0.0
Total Assets	[12]	0.8			0.8
Current Risk Management Liabilities	[12]	3.5			3.1
Long-term Risk Management Liabilities	[12]	1.8			2.1
Derivative Liability	[12]	5.3			5.2
Total MTM Derivative Contract Net Assets (Liabilities)	[12]	$ (4.5)			$ (4.4)
Power [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		272.7			317.8
Power [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		25.0			40.9
Power [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		13.9			22.8
Power [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		11.6			13.3
Power [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		4.8			11.3
Power [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MWh		5.9			14.0
Coal [Member]
Commodity:
Derivative, Mass Notional Amount | T		3.4			4.4
Coal [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Mass Notional Amount | T		0.0			0.0
Coal [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Mass Notional Amount | T		1.1			1.6
Coal [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Mass Notional Amount | T		0.0			0.0
Coal [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Mass Notional Amount | T		0.0			0.0
Coal [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Mass Notional Amount | T		2.3			2.8
Natural Gas [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		42.7			38.2
Natural Gas [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.3			0.3
Natural Gas [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.2			0.2
Natural Gas [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.0			0.0
Natural Gas [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.2			0.2
Natural Gas [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Energy Notional Amount | MMBTU		0.2			0.2
Heating Oil and Gasoline [Member]
Commodity:
Derivative, Volume Notional Amount | gal		6.9			7.4
Heating Oil and Gasoline [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.3			1.4
Heating Oil and Gasoline [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.6			0.7
Heating Oil and Gasoline [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		1.5			1.6
Heating Oil and Gasoline [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.8			0.8
Heating Oil and Gasoline [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Volume Notional Amount | gal		0.9			0.9
Interest Rate Contract [Member]
Commodity:
Derivative, Notional Amount		$ 101.9			$ 113.5
Interest Rate Contract [Member] | Appalachian Power Co [Member]
Commodity:
Derivative, Notional Amount		1.2			2.4
Interest Rate Contract [Member] | Indiana Michigan Power Co [Member]
Commodity:
Derivative, Notional Amount		0.8			1.6
Interest Rate Contract [Member] | Ohio Power Co [Member]
Commodity:
Derivative, Notional Amount		0.0			0.0
Interest Rate Contract [Member] | Public Service Co Of Oklahoma [Member]
Commodity:
Derivative, Notional Amount		0.0			0.0
Interest Rate Contract [Member] | Southwestern Electric Power Co [Member]
Commodity:
Derivative, Notional Amount		0.0			$ 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		0.6		4.4
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
Transmission and Distribution Utilities Revenues [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(3.5)
Transmission and Distribution 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
Transmission and Distribution 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
Transmission and Distribution 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
Transmission and Distribution 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
Transmission and Distribution 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
Generation & Marketing Revenues [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		19.8		48.8
Generation & 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 & 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 & 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 & 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 & 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] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(0.8)		0.6
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		1.6		2.2
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		(3.5)		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		0.0
Sales to AEP Affiliates [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		0.0
Sales to AEP Affiliates [Member] | Appalachian Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		1.1
Sales to AEP Affiliates [Member] | Indiana Michigan Power Co [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		4.0
Sales to AEP Affiliates [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
Sales to AEP Affiliates [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
Sales to AEP Affiliates [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
Purchased Electricity for Resale [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		2.1		3.3
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		1.4		0.7
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		0.1		0.3
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		(0.7)		(0.9)
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		(0.1)		(0.1)
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		(0.1)		(0.1)
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		(0.1)		(0.2)
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		(0.1)		(0.1)
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		(0.1)		(0.1)
Maintenance Expense [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts		(0.8)		(0.8)
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		(0.2)		(0.2)
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		(0.1)		(0.1)
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		(0.1)		(0.1)
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		(0.1)		(0.1)
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		(0.1)		(0.1)
Regulatory Assets [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[13]	(11.1)		(4.1)
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	[13]	0.2		0.7
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	[13]	0.3		(0.5)
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	[13]	(11.4)		0.0
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	[13]	(0.5)		(0.8)
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	[13]	0.1		(3.5)
Regulatory Liabilities [Member]
Amount of Gain (Loss) Recognized on Risk Management Contracts
Amount of Gain (Loss) Recognized on Risk Management Contracts	[13]	12.7		3.9
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	[13]	15.9		1.7
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	[13]	3.9		(3.0)
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	[13]	(15.2)		4.7
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	[13]	0.0		0.0
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	[13]	$ 4.5		$ 3.9

[1] Represents the amount of collateral AEP subsidiaries would have been required to post for other significant non-derivative contracts including AGR jointly owned plant contracts and various other commodity related contacts.

[2] 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.’’

[3] The March 31, 2016 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 1 matures $(5) million in 2016 and $(5) million in periods 2017-2019; Level 2 matures $3 million in 2016, $9 million in periods 2017-2019, $3 million in periods 2020-2021 and $1 million in periods 2022-2032; Level 3 matures $17 million in 2016, $37 million in periods 2017-2019, $21 million in periods 2020-2021 and $69 million in periods 2022-2032. Risk management commodity contracts are substantially comprised of power contracts.

[4] The December 31, 2015 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 1 matures $(9) million in 2016 and $(4) million in periods 2017-2019; Level 2 matures $2 million in 2016, $18 million in periods 2017-2019 and $4 million in periods 2020-2021; Level 3 matures $28 million in 2016, $29 million in periods 2017-2019, $19 million in periods 2020-2021 and $76 million in periods 2022-2032. Risk management commodity contracts are substantially comprised of power contracts.

[5] Substantially comprised of power contracts for APCo, I&M and OPCo and coal contracts for PSO and SWEPCo.

[6] Hedging Assets and Hedging Liabilities are included in Risk Management Assets and Liabilities on the condensed balance sheets.

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

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

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

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

[11] There are no derivative contracts subject to a master netting arrangement or similar agreement which are not offset in the statement of financial position.

[12] There are no derivative contracts subject to a master netting arrangement or similar agreement which are not offset in the statement of financial position.

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