Dispostions and Impairments (Details) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($) MW	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	$ 780.3		$ 616.4		$ 1,506.7	$ 1,240.1
AEP Texas Inc. [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	118.0		106.5		235.0	215.3
AEP Transmission Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	18.5		11.3		35.1	20.4
Appalachian Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	109.9		139.2		248.1	253.1
Indiana Michigan Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	130.4		159.7		276.5	296.8
Ohio Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	199.0		131.7		371.2	254.0
Public Service Co Of Oklahoma [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	93.7		76.1		180.5	144.4
Southwestern Electric Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	$ 98.0		$ 74.8		$ 192.9	$ 153.7
Generation And Marketing [Member] | Merchant Coal-Fired Generation Assets [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations				$ 4.0
Generation And Marketing [Member] | Zimmer Plant Assets [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations				$ 7.0
Corporate and Other [Member] | Other Assets [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations		$ 21.0
Gavin, Waterford, Darby and Lawrenceburg Plants [Member] | Generation And Marketing [Member]
Competitive generation assets sold to a nonaffiliated party (in MWs). | MW				5,329
Proceeds from Sales of Assets, Investing Activities				$ 2,200.0
Discontinued Operations and Disposal Groups (Textuals)
Cash Proceeds from Sale of Disposition Plants, Net				1,200.0
Pre-tax Gain on Sale of Plants				$ 226.0
Coal [Member] | Wm. H. Zimmer Generating Station [Member] | Generation And Marketing [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share							25.40%