Property, Plant and Equipment Property, Plant and Equipment (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Dec. 31, 2014
Asset Retirement Obligations (ARO)
Beginning Balance		$ 2,019,000
Accretion Expense		50,000
Liabilities Incurred		47,000
Liabilities Settled		(22,000)
Revisions in Cash Flow Estimates		48,000
Ending Balance		2,142,000
Property, Plant and Equipment (Textuals) [Abstract]
Asset Retirement Obligations (ARO) Liability for Nuclear Decommissioning of the Cook Plant		1,300,000	$ 1,300,000
Fair Value of Legally Restricted Assets		1,800,000	1,800,000
Appalachian Power Co [Member]
Asset Retirement Obligations (ARO)
Beginning Balance	[1],[2]	148,377
Accretion Expense		4,122
Liabilities Incurred		0
Liabilities Settled		(10,503)
Revisions in Cash Flow Estimates		13,962
Ending Balance	[1],[2]	155,958
Indiana Michigan Power Co [Member]
Asset Retirement Obligations (ARO)
Beginning Balance	[1],[2],[3]	1,342,549
Accretion Expense		31,731
Liabilities Incurred		0
Liabilities Settled		(1,222)
Revisions in Cash Flow Estimates		5,639
Ending Balance	[1],[2],[3]	1,378,697
Property, Plant and Equipment (Textuals) [Abstract]
Asset Retirement Obligations (ARO) Liability for Nuclear Decommissioning of the Cook Plant		1,300,000	1,300,000
Fair Value of Legally Restricted Assets		1,800,000	$ 1,800,000
Ohio Power Co [Member]
Asset Retirement Obligations (ARO)
Beginning Balance	[1],[4]	1,361
Accretion Expense		41
Liabilities Incurred		0
Liabilities Settled		(8)
Revisions in Cash Flow Estimates		0
Ending Balance	[1],[4]	1,394
Public Service Co Of Oklahoma [Member]
Asset Retirement Obligations (ARO)
Beginning Balance	[1],[2]	38,020
Accretion Expense		1,214
Liabilities Incurred		5,336
Liabilities Settled		(115)
Revisions in Cash Flow Estimates		1,916
Ending Balance	[1],[2]	46,371
Southwestern Electric Power Co [Member]
Asset Retirement Obligations (ARO)
Beginning Balance	[1],[2],[5]	94,394
Accretion Expense		2,725
Liabilities Incurred		12,191
Liabilities Settled		(2,189)
Revisions in Cash Flow Estimates		6,348
Ending Balance	[1],[2],[5]	$ 113,469

[1] Includes ARO related to asbestos removal.

[2] Includes ARO related to ash disposal facilities.

[3] Includes ARO related to nuclear decommissioning costs for the Cook Plant of $1.3 billion and $1.3 billion as of June 30, 2015 and December 31, 2014.

[4] Not impacted by the CCR rule.

[5] Includes ARO related to Sabine and DHLC.