Significant Accounting Matters (Details) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Voluntary Retirement Incentive Program [Abstract]
Employees Participating in Voluntary Retirement Incentive Program				200
Percent of Voluntary Retirement Incentive Program Expense related to AEP Service Corporation				92.00%
Amounts Attributable to AEP Common Shareholders
Earnings Attributable to Common Shareholders		$ 748.6	$ 733.5	$ 1,764.6	$ 1,767.6
Weighted Average Number of Basic AEP Common Shares Outstanding | shares		496,177,968	493,839,034	495,479,190	493,579,430
Total Basic Earnings Per Share Attributable to AEP Common Shareholders | $ / shares		$ 1.51	$ 1.49	$ 3.56	$ 3.58
Weighted Average Dilutive Effect of:
Weighted Average Number of Diluted AEP Common Shares Outstanding | shares		497,458,523	495,461,509	496,916,187	495,105,986
Total Diluted Earnings Per Share Attributable to AEP Common Shareholders | $ / shares		$ 1.50	$ 1.48	$ 3.55	$ 3.57
Organization and Summary of Significant Accounting Policies (Textuals)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares				0	0
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents		$ 409.7		$ 409.7		$ 246.8
Restricted Cash		54.1		54.1		185.8
Total Cash, Cash Equivalents and Restricted Cash		463.8	$ 489.8	463.8	$ 489.8	432.6	$ 444.1
Proceeds from Issuance of Debt	[1]			4,036.9
Junior Subordinated Debt [Member]
Cash, Cash Equivalents and Restricted Cash
Proceeds from Issuance of Debt	[1]			850.0
Lump Sum Salary Payments and Cash Subsidies [Member]
Voluntary Retirement Incentive Program [Abstract]
Voluntary Retirement Incentive Program Expense				13.0
Incremental Long-Term Incentive Plan Grants [Member]
Voluntary Retirement Incentive Program [Abstract]
Voluntary Retirement Incentive Program Expense				5.0
AEP Texas Inc. [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents		0.1		0.1		3.1
Restricted Cash		44.8		44.8		154.7
Total Cash, Cash Equivalents and Restricted Cash		44.9	114.4	44.9	114.4	157.8	159.8
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		3.9		3.9		3.3
Restricted Cash		9.3		9.3		23.5
Total Cash, Cash Equivalents and Restricted Cash		13.2	20.6	13.2	20.6	26.8	29.8
Indiana Michigan Power Co [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents		2.8	2.5	2.8	2.5	2.0	2.4
Ohio Power Co [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents		6.6		6.6		3.7
Total Cash, Cash Equivalents and Restricted Cash		6.6	4.7	6.6	4.7	3.7	32.5
Public Service Co Of Oklahoma [Member]
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents		3.0	2.9	3.0	2.9	1.5	2.0
Southwestern Electric Power Co [Member]
Amounts Attributable to AEP Common Shareholders
Earnings Attributable to Common Shareholders		87.9	110.5	161.8	144.5
Cash, Cash Equivalents and Restricted Cash
Cash and Cash Equivalents		$ 25.6	$ 21.4	$ 25.6	$ 21.4	$ 1.6	$ 24.5
Restricted Stock Units and Performance Share Units [Member]
Weighted Average Dilutive Effect of:
Weighted Average Dilutive Effect of Shares | shares		1,300,000	1,700,000	1,400,000	1,500,000
Dilutive Securities, Effect on Basic Earnings Per Share | $ / shares		$ (0.01)	$ (0.01)	$ (0.01)	$ (0.01)

[1] Amounts indicated on the statements of cash flows are net of issuance costs and premium or discount and will not tie to the issuance amounts.(b)See “Equity Units” section below for additional information.