Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($)		3 Months Ended		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		$ 39,144,200,000		$ 36,801,000,000
Long Term Debt, Fair Value	[1]	36,126,400,000		32,915,900,000
Other Temporary Investments
Cost		230,000,000.0		223,600,000
Gross Unrealized Gains		21,800,000		19,400,000
Gross Unrealized Losses		(7,200,000)		(8,300,000)
Other Short-term Investments		244,600,000		234,700,000
Debt and Equity Securities Within Other Temporary Investments
Proceeds from Investment Sales		0	$ 3,900,000
Purchases of Investments		1,000,000.0	800,000
Gross Realized Gains on Investment Sales		0	300,000
Gross Realized Losses on Investment Sales		0	100,000
Nuclear Trust Fund Investments
Fair Value		3,501,100,000		3,341,200,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,501,100,000		3,341,200,000
Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,587,000,000		1,496,300,000
Gross Unrealized Loss		(15,400,000)		(29,000,000.0)
Securities Activity Within Decommissioning and SNF Trusts
Proceeds from Investment Sales		517,600,000	493,500,000
Purchases of Investments		536,300,000	507,700,000
Gross Realized Gains on Investment Sales		48,500,000	5,800,000
Gross Realized Losses on Investment Sales		8,600,000	7,200,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		347,800,000
After 1 year through 5 years		489,100,000
After 5 years through 10 years		215,600,000
After 10 years		224,400,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,300,000,000		1,200,000,000
Adjusted Cost of Domestic Equity Securities		635,000,000		654,000,000
Other than Temporary Impairment Losses, Investments		(30,500,000)		(28,500,000)
Cash [Member]
Other Temporary Investments
Cost	[2]	50,000,000.0		47,100,000
Gross Unrealized Gains	[2]	0		0
Gross Unrealized Losses	[2]	0		0
Other Short-term Investments	[2]	50,000,000.0		47,100,000
Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,276,900,000		1,188,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,276,900,000		1,188,700,000
Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		21,900,000		12,600,000
Gross Unrealized Loss		(12,500,000)		(22,600,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(30,500,000)		(28,500,000)
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost	[3]	153,400,000		152,400,000
Gross Unrealized Gains	[3]	0		0
Gross Unrealized Losses	[3]	(7,200,000)		(8,300,000)
Other Short-term Investments	[3]	146,200,000		144,100,000
Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	2,197,700,000		2,131,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	2,197,700,000		2,131,300,000
Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,565,100,000		1,483,700,000
Gross Unrealized Loss		(2,900,000)		(6,400,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0		0
Mutual Funds Equity [Member]
Other Temporary Investments
Cost		15,200,000		15,100,000
Gross Unrealized Gains		21,800,000		19,400,000
Gross Unrealized Losses		0		0
Other Short-term Investments	[4]	37,000,000.0		34,500,000
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[5]	26,500,000		21,200,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[5]	26,500,000		21,200,000
Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0		0
Gross Unrealized Loss		0		0
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0		0
US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments
Fair Value		1,207,600,000		1,123,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,207,600,000		1,123,800,000
US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		20,900,000		11,800,000
Gross Unrealized Loss		(6,400,000)		(14,900,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(28,300,000)		(18,800,000)
Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		66,000,000.0		61,600,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		66,000,000.0		61,600,000
Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,000,000.0		700,000
Gross Unrealized Loss		(6,100,000)		(7,700,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(2,200,000)		(9,600,000)
State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		3,300,000		3,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,300,000		3,300,000
State and Local Jurisdiction [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0		100,000
Gross Unrealized Loss		0		0
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0		(100,000)
Other Cash Deposits [Member]
Other Temporary Investments
Cost		11,400,000		9,000,000.0
Gross Unrealized Gains		0		0
Gross Unrealized Losses		0		0
Other Short-term Investments		11,400,000		9,000,000.0
AEP Texas Inc. [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,522,000,000		5,657,800,000
Long Term Debt, Fair Value		5,009,500,000		5,045,800,000
AEP Transmission Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,472,100,000		4,782,800,000
Long Term Debt, Fair Value		4,836,200,000		3,940,500,000
Appalachian Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,398,700,000		5,410,500,000
Long Term Debt, Fair Value		5,227,700,000		5,079,200,000
Indiana Michigan Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,489,000,000		3,260,800,000
Long Term Debt, Fair Value		3,249,100,000		2,929,000,000
Nuclear Trust Fund Investments
Fair Value		3,501,100,000		3,341,200,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,501,100,000		3,341,200,000
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,587,000,000		1,496,300,000
Gross Unrealized Loss		(15,400,000)		(29,000,000.0)
Securities Activity Within Decommissioning and SNF Trusts
Proceeds from Investment Sales		517,600,000	493,500,000
Purchases of Investments		536,300,000	507,700,000
Gross Realized Gains on Investment Sales		48,500,000	5,800,000
Gross Realized Losses on Investment Sales		8,600,000	$ 7,200,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		347,800,000
After 1 year through 5 years		489,100,000
After 5 years through 10 years		215,600,000
After 10 years		224,400,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,300,000,000		1,200,000,000
Adjusted Cost of Domestic Equity Securities		635,000,000		654,000,000
Other than Temporary Impairment Losses, Investments		(30,500,000)		(28,500,000)
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,276,900,000		1,188,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,276,900,000		1,188,700,000
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		21,900,000		12,600,000
Gross Unrealized Loss		(12,500,000)		(22,600,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(30,500,000)		(28,500,000)
Indiana Michigan Power Co [Member] | Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	2,197,700,000		2,131,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	2,197,700,000		2,131,300,000
Indiana Michigan Power Co [Member] | Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,565,100,000		1,483,700,000
Gross Unrealized Loss		(2,900,000)		(6,400,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0		0
Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[5]	26,500,000		21,200,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[5]	26,500,000		21,200,000
Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0		0
Gross Unrealized Loss		0		0
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0		0
Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments
Fair Value		1,207,600,000		1,123,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,207,600,000		1,123,800,000
Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		20,900,000		11,800,000
Gross Unrealized Loss		(6,400,000)		(14,900,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(28,300,000)		(18,800,000)
Indiana Michigan Power Co [Member] | Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		66,000,000.0		61,600,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		66,000,000.0		61,600,000
Indiana Michigan Power Co [Member] | Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,000,000.0		700,000
Gross Unrealized Loss		(6,100,000)		(7,700,000)
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(2,200,000)		(9,600,000)
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		3,300,000		3,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,300,000		3,300,000
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0		100,000
Gross Unrealized Loss		0		0
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0		(100,000)
Ohio Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,970,800,000		2,970,300,000
Long Term Debt, Fair Value		2,566,600,000		2,516,600,000
Public Service Co Of Oklahoma [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,383,600,000		1,912,800,000
Long Term Debt, Fair Value		2,172,600,000		1,635,800,000
Southwestern Electric Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,644,800,000		3,391,600,000
Long Term Debt, Fair Value		3,195,900,000		2,870,900,000
Equity Units [Member]
Book Values and Fair Values of Long - term Debt
Long Term Debt, Fair Value		$ 856,000,000		$ 877,000,000

[1] The fair value amounts include debt related to AEP’s Equity Units and had a fair value of $856 million and $877 million as of March 31, 2023 and December 31, 2022, respectively. See “Equity Units” section of Note 12 for additional information.

[2] Primarily represents amounts held for the repayment of debt.

[3] Primarily short and intermediate maturities which may be sold and do not contain maturity dates.

[4] Amounts represent publicly traded equity securities and equity-based mutual funds.

[5] Amounts in “Other’’ column primarily represent accrued interest receivables from financial institutions.  Level 1 amounts primarily represent investments in money market funds.