Significant Accounting Matters (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Amounts Attributable to AEP Common Shareholders
Net Income (Loss) Available to Common Stockholders, Basic	$ 592.2	$ 501.2
Weighted Average Number of Basic AEP Common Shares Outstanding	491,712,042	491,108,392
Basic Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 1.20	$ 1.02
Weighted Average Dilutive Effect of:
Weighted Average Number of Diluted AEP Common Shares Outstanding	492,031,975	491,332,305
Diluted Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 1.20	$ 1.02
Organization and Summary of Significant Accounting Policies (Textuals) [Abstract]
Antidilutive Shares Outstanding	0	0
Southwestern Electric Power Co [Member]
Amounts Attributable to AEP Common Shareholders
Net Income (Loss) Available to Common Stockholders, Basic	$ 16.3	$ 23.4
Restricted Stock Units and Performance Share Units [Member]
Weighted Average Dilutive Effect of:
Weighted Average Dilutive Effect of Shares	300,000	200,000
Dilutive Securities, Effect on Basic Earnings Per Share	$ 0	$ 0