Cost Reduction Program (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Severance Costs			$ 29,000
Vertically Integrated Utilities [Member]
Cost Reduction Initiatives (Textuals) [Abstract]
Current Period Severance Costs Percentage	68.00%
Generation and Marketing [Member]
Cost Reduction Initiatives (Textuals) [Abstract]
Current Period Severance Costs Percentage	32.00%
Disposition Plant Severance [Member]
Cost Reduction Initiatives [Abstract]
Beginning Balance	29,000
Incurred	0
Settled	(1,000)
Adjustments	0
Remaining Balance	28,000
Appalachian Power Co [Member]
Severance Costs			7,112
Cost Reduction Initiatives [Abstract]
Beginning Balance	9,304
Expense Allocation from AEPSC	(4)
Incurred	(187)
Settled	(98)	[1]
Adjustments	0
Remaining Balance	9,015		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	90
Settled	(5)
Adjustments	0
Remaining Balance	8,106		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	(2)
Incurred	0
Settled	(111)
Adjustments	0
Remaining Balance	21		134
Southwestern Electric Power Co [Member]
Severance Costs			289
Cost Reduction Initiatives [Abstract]
Beginning Balance	84
Expense Allocation from AEPSC	(3)
Incurred	0
Settled	(80)
Adjustments	0
Remaining Balance	$ 1		$ 84

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