Significant Accounting Matters (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Amounts Attributable to AEP Common Shareholders
Net Income (Loss) Available to Common Stockholders, Basic	$ 454.4	$ 592.2
Weighted Average Number of Basic AEP Common Shares Outstanding	492,267,402	491,712,042
Basic Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 0.92	$ 1.20
Weighted Average Dilutive Effect of:
Weighted Average Number of Diluted AEP Common Shares Outstanding	493,127,300	492,031,975
Diluted Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 0.92	$ 1.20
Organization and Summary of Significant Accounting Policies (Textuals) [Abstract]
Antidilutive Shares Outstanding	0	0
Cash, Cash Equivalents and Restricted Cash [Abstract]
Cash and Cash Equivalents	$ 183.4		$ 214.6
Restricted Cash	133.1		198.0
Total Cash, Cash Equivalents and Restricted Cash	316.5		412.6
Total Cash, Cash Equivalents and Restricted Cash	$ 316.5	$ 299.4	412.6	$ 403.5
Restricted Stock Units and Performance Share Units [Member]
Weighted Average Dilutive Effect of:
Weighted Average Dilutive Effect of Shares	800,000	300,000
Dilutive Securities, Effect on Basic Earnings Per Share	$ 0	$ 0
AEP Texas Inc. [Member]
Cash, Cash Equivalents and Restricted Cash [Abstract]
Cash and Cash Equivalents	$ 0.1		2.0
Restricted Cash	107.1		155.2
Total Cash, Cash Equivalents and Restricted Cash	107.2		157.2
Total Cash, Cash Equivalents and Restricted Cash	107.2	$ 100.5	157.2	146.9
Appalachian Power Co [Member]
Cash, Cash Equivalents and Restricted Cash [Abstract]
Cash and Cash Equivalents	1.2		2.9
Restricted Cash	10.1		16.3
Total Cash, Cash Equivalents and Restricted Cash	11.3	11.0	19.2	18.5
Ohio Power Co [Member]
Cash, Cash Equivalents and Restricted Cash [Abstract]
Cash and Cash Equivalents	1.4		3.1
Restricted Cash	15.9		26.6
Total Cash, Cash Equivalents and Restricted Cash	$ 17.3	$ 19.0	$ 29.7	$ 30.3