Significant Accounting Matters (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Amounts Attributable to AEP Common Shareholders
Earnings Attributable to Common Shareholders	$ 733.5	$ 577.6	$ 1,767.6	$ 1,560.4
Weighted Average Number of Basic AEP Common Shares Outstanding	493,839,034	492,984,741	493,579,430	492,649,456
Total Basic Earnings Per Share Attributable to AEP Common Shareholders	$ 1.49	$ 1.17	$ 3.58	$ 3.17
Weighted Average Dilutive Effect of:
Weighted Average Number of Diluted AEP Common Shares Outstanding	495,461,509	493,940,543	495,105,986	493,526,937
Total Diluted Earnings Per Share Attributable to AEP Common Shareholders	$ 1.48	$ 1.17	$ 3.57	$ 3.16
Organization and Summary of Significant Accounting Policies (Textuals)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			0	0
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	$ 348.8		$ 348.8		$ 234.1
Restricted Cash	141.0		141.0		210.0
Total Cash, Cash Equivalents and Restricted Cash	489.8		489.8		444.1
Total Cash, Cash Equivalents and Restricted Cash	489.8	$ 937.5	489.8	$ 937.5	444.1	$ 412.6
AEP Texas Inc. [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	0.1		0.1		3.1
Restricted Cash	114.3		114.3		156.7
Total Cash, Cash Equivalents and Restricted Cash	114.4		114.4		159.8
Total Cash, Cash Equivalents and Restricted Cash	114.4	124.3	114.4	124.3	159.8	157.2
AEP Transmission Co [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	0.0	0.0	0.0	0.0	0.0	0.0
Appalachian Power Co [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	3.5		3.5		4.2
Restricted Cash	17.1		17.1		25.6
Total Cash, Cash Equivalents and Restricted Cash	20.6	12.1	20.6	12.1	29.8	19.2
Indiana Michigan Power Co [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	2.5	1.6	2.5	1.6	2.4	1.3
Ohio Power Co [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	4.7		4.7		4.9
Restricted Cash	0.0		0.0		27.6
Total Cash, Cash Equivalents and Restricted Cash	4.7	18.7	4.7	18.7	32.5	29.7
Public Service Co Of Oklahoma [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	2.9	1.9	2.9	1.9	2.0	1.6
Southwestern Electric Power Co [Member]
Amounts Attributable to AEP Common Shareholders
Earnings Attributable to Common Shareholders	110.5	88.2	144.5	137.6
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents	$ 21.4	$ 2.5	$ 21.4	$ 2.5	$ 24.5	$ 1.6
Restricted Stock Units and Performance Share Units [Member]
Weighted Average Dilutive Effect of:
Weighted Average Dilutive Effect of Shares	1,700,000	900,000	1,500,000	900,000
Dilutive Securities, Effect on Basic Earnings Per Share	$ (0.01)	$ 0	$ (0.01)	$ (0.01)