Disposition Plant Severance (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Severance Costs			$ 29,000
Vertically Integrated Utilities [Member]
Cost Reduction Initiatives Text [Abstract]
Current Period Severance Costs Percentage		68.00%
Generation And Marketing [Member]
Cost Reduction Initiatives Text [Abstract]
Current Period Severance Costs Percentage		32.00%
Disposition Plant Severance [Member]
Cost Reduction Initiatives [Abstract]
Beginning Balance		$ 29,000
Incurred		3,000
Settled		(21,000)
Adjustments		0
Remaining Balance		11,000	29,000
Appalachian Power Co [Member]
Severance Costs			7,112
Cost Reduction Initiatives [Abstract]
Beginning Balance		9,304
Expense Allocation from Aepsc		(6)
Incurred		849
Settled	[1]	(6,385)
Adjustments		(119)
Remaining Balance		3,643	9,304
Indiana Michigan Power Co [Member]
Severance Costs			8,185
Cost Reduction Initiatives [Abstract]
Beginning Balance		8,023
Expense Allocation from Aepsc		(2)
Incurred		351
Settled		(5,110)
Adjustments		0
Remaining Balance		3,262	8,023
Ohio Power Co [Member]
Severance Costs			80
Public Service Co Of Oklahoma [Member]
Severance Costs			288
Cost Reduction Initiatives [Abstract]
Beginning Balance		134
Expense Allocation from Aepsc		(3)
Incurred		415
Settled		(121)
Adjustments		0
Remaining Balance		425	134
Southwestern Electric Power Co [Member]
Severance Costs			289
Cost Reduction Initiatives [Abstract]
Beginning Balance		84
Expense Allocation from Aepsc		(4)
Incurred		0
Settled		(79)
Adjustments		0
Remaining Balance		$ 1	$ 84

[1] Settled includes amounts received from affiliates for expenses related to joint plant.