Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Cash Flow Hedges, Tax	$ 0.5	$ 4.6	$ 1.2	$ (4.1)
Securities Available for Sale, Tax	0.0	0.4	0.0	1.0
Amortization of Pension and OPEB Deferred Costs, Tax	(0.3)	0.2	(0.7)	0.3
AEP Texas Inc. [Member]
Cash Flow Hedges, Tax	0.0	0.1	0.1	0.2
Amortization of Pension and OPEB Deferred Costs, Tax	0.0	0.1	0.0	0.1
Appalachian Power Co [Member]
Cash Flow Hedges, Tax	0.0	(0.1)	(0.1)	(0.2)
Amortization of Pension and OPEB Deferred Costs, Tax	(0.2)	(0.1)	(0.4)	(0.3)
Indiana Michigan Power Co [Member]
Cash Flow Hedges, Tax	0.1	0.2	0.2	0.4
Ohio Power Co [Member]
Cash Flow Hedges, Tax	(0.1)	(0.2)	(0.2)	(0.3)
Public Service Co Of Oklahoma [Member]
Cash Flow Hedges, Tax	(0.1)	(0.1)	(0.2)	(0.2)
Southwestern Electric Power Co [Member]
Cash Flow Hedges, Tax	0.1	0.2	0.2	0.4
Amortization of Pension and OPEB Deferred Costs, Tax	$ (0.1)	$ (0.1)	$ (0.2)	$ (0.2)