Dispostions and Impairments (Details)	3 Months Ended					9 Months Ended
	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($) MW	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	$ 826,000,000			$ 644,000,000		$ 2,332,700,000	$ 1,884,100,000
AEP Texas Inc. [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	133,400,000			117,500,000		368,400,000	332,800,000
AEP Transmission Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	24,500,000			18,400,000		59,600,000	38,800,000
Appalachian Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	131,900,000			117,000,000		380,000,000	370,100,000
Indiana Michigan Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	149,300,000			142,000,000		425,800,000	438,800,000
Ohio Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	215,200,000			126,900,000		586,400,000	380,900,000
Public Service Co Of Oklahoma [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	106,300,000			84,500,000		286,800,000	228,900,000
Southwestern Electric Power Co [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations	99,100,000			$ 81,200,000		292,000,000	$ 234,900,000
Generation And Marketing [Member] | Racine Hydroelectric Plant [Member]
Discontinued Operations and Disposal Groups (Textuals)
Property, Plant, and Equipment, Fair Value Disclosure	0		$ 0			$ 0
Other Asset Impairment Charges	$ 35,000,000		$ 43,000,000
Generation And Marketing [Member] | Merchant Coal-Fired Generation Assets [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations					$ 4,000,000
Generation And Marketing [Member] | Zimmer Plant Assets [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations					$ 7,000,000
Corporate and Other [Member] | Other Assets [Member]
Discontinued Operations and Disposal Groups (Textuals)
Utilities Operating Expense, Operations		$ 21,000,000
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					$ 2,200,000,000
Discontinued Operations and Disposal Groups (Textuals)
Cash Proceeds from Sale of Disposition Plants, Net					1,200,000,000
Pre-tax Gain on Sale of Plants					$ 226,000,000
Coal [Member] | Wm. H. Zimmer Generating Station [Member] | Generation And Marketing [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share								25.40%