Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		$ 39,489,100,000		$ 39,489,100,000		$ 36,801,000,000
Long Term Debt, Fair Value	[1]	33,559,800,000		33,559,800,000		32,915,900,000
Other Temporary Investments
Cost		252,600,000		252,600,000		223,600,000
Gross Unrealized Gains		22,600,000		22,600,000		19,400,000
Gross Unrealized Losses		(10,400,000)		(10,400,000)		(8,300,000)
Other Short-term Investments		264,800,000		264,800,000		234,700,000
Debt and Equity Securities Within Other Temporary Investments
Proceeds from Investment Sales		800,000	$ 0	800,000	$ 15,000,000.0
Purchases of Investments		14,600,000	11,800,000	16,900,000	13,400,000
Gross Realized Gains on Investment Sales		300,000	0	300,000	3,600,000
Gross Realized Losses on Investment Sales		0	0	0	500,000
Nuclear Trust Fund Investments
Fair Value		3,539,700,000		3,539,700,000		3,341,200,000
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments				2,199,700,000	1,868,200,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,539,700,000		3,539,700,000		3,341,200,000
Spent Nuclear Fuel and Decommissioning Trusts [Member]
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments		949,500,000	601,600,000	2,182,800,000	1,854,800,000
Realized Investment Gains (Losses)		36,800,000	24,600,000	91,600,000	41,300,000
Gain (Loss) on Investments		7,700,000	8,400,000	20,000,000.0	33,500,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		393,600,000		393,600,000
After 1 year through 5 years		504,400,000		504,400,000
After 5 years through 10 years		188,600,000		188,600,000
After 10 years		258,100,000		258,100,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,400,000,000		1,400,000,000		1,200,000,000
Adjusted Cost of Domestic Equity Securities		556,000,000		556,000,000		654,000,000
Other than Temporary Impairment Losses, Investments				(43,800,000)		(28,500,000)
Proceeds from Sale of Other Investments		933,000,000.0	588,500,000	2,139,300,000	1,818,400,000
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(45,100,000)		(45,100,000)		(29,000,000.0)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,621,500,000		1,621,500,000		1,496,300,000
Cash [Member]
Other Temporary Investments
Cost	[2]	53,800,000		53,800,000		47,100,000
Gross Unrealized Gains	[2]	0		0		0
Gross Unrealized Losses	[2]	0		0		0
Other Short-term Investments	[2]	53,800,000		53,800,000		47,100,000
Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,344,700,000		1,344,700,000		1,188,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,344,700,000		1,344,700,000		1,188,700,000
Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(43,800,000)		(28,500,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(43,200,000)		(43,200,000)		(22,600,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,000,000.0		1,000,000.0		12,600,000
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost	[3]	170,400,000		170,400,000		152,400,000
Gross Unrealized Gains	[3]	0		0		0
Gross Unrealized Losses	[3]	(10,400,000)		(10,400,000)		(8,300,000)
Other Short-term Investments	[3]	160,000,000.0		160,000,000.0		144,100,000
Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	2,174,500,000		2,174,500,000		2,131,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	2,174,500,000		2,174,500,000		2,131,300,000
Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(1,900,000)		(1,900,000)		(6,400,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,620,500,000		1,620,500,000		1,483,700,000
Mutual Funds Equity [Member]
Other Temporary Investments
Cost		15,000,000.0		15,000,000.0		15,100,000
Gross Unrealized Gains		22,600,000		22,600,000		19,400,000
Gross Unrealized Losses		0		0		0
Other Short-term Investments	[4]	37,600,000		37,600,000		34,500,000
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[5]	20,500,000		20,500,000		21,200,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[5]	20,500,000		20,500,000		21,200,000
Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0		0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0		0		0
US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments
Fair Value		1,204,700,000		1,204,700,000		1,123,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,204,700,000		1,204,700,000		1,123,800,000
US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(38,500,000)		(18,800,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(30,800,000)		(30,800,000)		(14,900,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		600,000		600,000		11,800,000
Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		136,800,000		136,800,000		61,600,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		136,800,000		136,800,000		61,600,000
Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(5,300,000)		(9,600,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(12,400,000)		(12,400,000)		(7,700,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		400,000		400,000		700,000
State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		3,200,000		3,200,000		3,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,200,000		3,200,000		3,300,000
State and Local Jurisdiction [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				0		(100,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0		0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0		0		100,000
Other Cash Deposits [Member]
Other Temporary Investments
Cost		13,400,000		13,400,000		9,000,000.0
Gross Unrealized Gains		0		0		0
Gross Unrealized Losses		0		0		0
Other Short-term Investments		13,400,000		13,400,000		9,000,000.0
AEP Texas Inc. [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,926,700,000		5,926,700,000		5,657,800,000
Long Term Debt, Fair Value		4,963,800,000		4,963,800,000		5,045,800,000
AEP Transmission Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,473,700,000		5,473,700,000		4,782,800,000
Long Term Debt, Fair Value		4,270,800,000		4,270,800,000		3,940,500,000
Appalachian Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,587,300,000		5,587,300,000		5,410,500,000
Long Term Debt, Fair Value		4,901,400,000		4,901,400,000		5,079,200,000
Indiana Michigan Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,443,600,000		3,443,600,000		3,260,800,000
Long Term Debt, Fair Value		2,920,600,000		2,920,600,000		2,929,000,000
Nuclear Trust Fund Investments
Fair Value		3,539,700,000		3,539,700,000		3,341,200,000
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments				2,182,800,000	1,854,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,539,700,000		3,539,700,000		3,341,200,000
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments		949,500,000	601,600,000	2,182,800,000	1,854,800,000
Realized Investment Gains (Losses)		36,800,000	24,600,000	91,600,000	41,300,000
Gain (Loss) on Investments		7,700,000	8,400,000	20,000,000.0	33,500,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		393,600,000		393,600,000
After 1 year through 5 years		504,400,000		504,400,000
After 5 years through 10 years		188,600,000		188,600,000
After 10 years		258,100,000		258,100,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,400,000,000		1,400,000,000		1,200,000,000
Adjusted Cost of Domestic Equity Securities		556,000,000		556,000,000		654,000,000
Other than Temporary Impairment Losses, Investments				(43,800,000)		(28,500,000)
Proceeds from Sale of Other Investments		933,000,000.0	$ 588,500,000	2,139,300,000	$ 1,818,400,000
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(45,100,000)		(45,100,000)		(29,000,000.0)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,621,500,000		1,621,500,000		1,496,300,000
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,344,700,000		1,344,700,000		1,188,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,344,700,000		1,344,700,000		1,188,700,000
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(43,800,000)		(28,500,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(43,200,000)		(43,200,000)		(22,600,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,000,000.0		1,000,000.0		12,600,000
Indiana Michigan Power Co [Member] | Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	2,174,500,000		2,174,500,000		2,131,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	2,174,500,000		2,174,500,000		2,131,300,000
Indiana Michigan Power Co [Member] | Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(1,900,000)		(1,900,000)		(6,400,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,620,500,000		1,620,500,000		1,483,700,000
Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[5]	20,500,000		20,500,000		21,200,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[5]	20,500,000		20,500,000		21,200,000
Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0		0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0		0		0
Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments
Fair Value		1,204,700,000		1,204,700,000		1,123,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,204,700,000		1,204,700,000		1,123,800,000
Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(38,500,000)		(18,800,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(30,800,000)		(30,800,000)		(14,900,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		600,000		600,000		11,800,000
Indiana Michigan Power Co [Member] | Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		136,800,000		136,800,000		61,600,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		136,800,000		136,800,000		61,600,000
Indiana Michigan Power Co [Member] | Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(5,300,000)		(9,600,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(12,400,000)		(12,400,000)		(7,700,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		400,000		400,000		700,000
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		3,200,000		3,200,000		3,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,200,000		3,200,000		3,300,000
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				0		(100,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0		0		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0		0		100,000
Ohio Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,366,200,000		3,366,200,000		2,970,300,000
Long Term Debt, Fair Value		2,645,200,000		2,645,200,000		2,516,600,000
Public Service Co Of Oklahoma [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,384,200,000		2,384,200,000		1,912,800,000
Long Term Debt, Fair Value		1,942,500,000		1,942,500,000		1,635,800,000
Southwestern Electric Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,646,200,000		3,646,200,000		3,391,600,000
Long Term Debt, Fair Value		2,944,800,000		2,944,800,000		2,870,900,000
Equity Units [Member]
Book Values and Fair Values of Long - term Debt
Long Term Debt, Fair Value		$ 0		$ 0		$ 877,000,000

[1] The fair value amounts include debt related to AEP’s Equity Units and had a fair value of $0 and $877 million as of September 30, 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.