Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		$ 41,974,400,000		$ 41,974,400,000		$ 40,143,200,000
Long Term Debt, Fair Value		40,104,200,000		40,104,200,000		37,325,700,000
Other Temporary Investments
Cost		253,200,000		253,200,000		243,500,000
Other Short-term Investments		282,000,000.0		282,000,000.0		263,200,000
Debt and Equity Securities Within Other Temporary Investments
Proceeds from Investment Sales		4,500,000	$ 800,000	7,500,000	$ 800,000
Purchases of Investments		6,000,000.0	14,600,000	9,000,000.0	16,900,000
Gross Realized Gains on Investment Sales		400,000	300,000	700,000	300,000
Gross Realized Losses on Investment Sales		300,000	0	500,000	0
Nuclear Trust Fund Investments
Fair Value		4,425,800,000		4,425,800,000		3,860,200,000
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments				2,398,000,000	2,199,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		4,425,800,000		4,425,800,000		3,860,200,000
Gain [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments				32,200,000		25,900,000
Loss [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments				(3,400,000)		(6,200,000)
Other [Member]
Other Temporary Investments
Other Short-term Investments		17,000,000.0		17,000,000.0		13,900,000
Nuclear Trust Fund Investments
Fair Value		10,600,000		10,600,000		9,000,000.0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		10,600,000		10,600,000		9,000,000.0
Spent Nuclear Fuel and Decommissioning Trusts [Member]
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments		1,201,900,000	949,500,000	2,389,000,000	2,182,800,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		401,200,000		401,200,000
After 1 year through 5 years		600,800,000		600,800,000
After 5 years through 10 years		249,700,000		249,700,000
After 10 years		336,100,000		336,100,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,500,000,000		1,500,000,000		1,400,000,000
Adjusted Cost of Domestic Equity Securities		541,000,000		541,000,000		568,000,000
Other than Temporary Impairment Losses, Investments				(19,500,000)		(41,800,000)
Proceeds from Sale of Other Investments		1,181,900,000	933,000,000.0	2,336,000,000	2,139,300,000
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(2,200,000)		(2,200,000)		(10,000,000.0)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		2,320,300,000		2,320,300,000		1,902,900,000
Spent Nuclear Fuel and Decommissioning Trusts [Member] | Gain [Member]
Securities Activity Within Decommissioning and SNF Trusts
Realized Investment Gains (Losses)		108,400,000	36,800,000	118,700,000	91,600,000
Spent Nuclear Fuel and Decommissioning Trusts [Member] | Loss [Member]
Securities Activity Within Decommissioning and SNF Trusts
Gain (Loss) on Investments		700,000	7,700,000	6,100,000	20,000,000.0
Cash [Member]
Other Temporary Investments
Cost	[1]	53,400,000		53,400,000		48,900,000
Other Short-term Investments	[1]	53,400,000		53,400,000		48,900,000
Cash [Member] | Gain [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments	[1]			0		0
Cash [Member] | Loss [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments	[1]			0		0
Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,587,800,000		1,587,800,000		1,406,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,587,800,000		1,587,800,000		1,406,800,000
Fixed Income Funds [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(19,500,000)		(41,800,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(1,900,000)		(1,900,000)		(9,100,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		49,300,000		49,300,000		33,400,000
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost	[2]	168,000,000.0		168,000,000.0		165,900,000
Other Short-term Investments	[2]	164,600,000		164,600,000		159,700,000
Mutual Funds Fixed Income [Member] | Gain [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments	[2]			0		0
Mutual Funds Fixed Income [Member] | Loss [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments	[2]			(3,400,000)		(6,200,000)
Mutual Funds Fixed Income [Member] | Other [Member]
Other Temporary Investments
Other Short-term Investments		0		0		0
Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[3]	2,811,800,000		2,811,800,000		2,436,600,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[3]	2,811,800,000		2,811,800,000		2,436,600,000
Domestic [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value	[3]	0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[3]	0		0		0
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		(300,000)		(300,000)		(900,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		2,271,000,000		2,271,000,000		1,869,500,000
Mutual Funds Equity [Member]
Other Temporary Investments
Cost		14,800,000		14,800,000		14,800,000
Other Short-term Investments	[3]	47,000,000.0		47,000,000.0		40,700,000
Mutual Funds Equity [Member] | Gain [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments				32,200,000		25,900,000
Mutual Funds Equity [Member] | Loss [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments				0		0
Mutual Funds Equity [Member] | Other [Member]
Other Temporary Investments
Other Short-term Investments	[3]	0		0		0
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	26,200,000		26,200,000		16,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	26,200,000		26,200,000		16,800,000
Cash and Cash Equivalents [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	10,600,000		10,600,000		9,000,000.0
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	10,600,000		10,600,000		9,000,000.0
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		1,370,500,000		1,370,500,000		1,273,000,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,370,500,000		1,370,500,000		1,273,000,000
US Government Agencies Debt Securities [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				(22,500,000)		(33,200,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(100,000)		(100,000)		(3,900,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		42,000,000.0		42,000,000.0		28,600,000
Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		215,600,000		215,600,000		132,100,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		215,600,000		215,600,000		132,100,000
Corporate Debt [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments				3,000,000.0		(8,600,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(1,800,000)		(1,800,000)		(5,200,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		7,300,000		7,300,000		4,800,000
State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		1,700,000		1,700,000		1,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,700,000		1,700,000		1,700,000
State and Local Jurisdiction [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
State and Local Jurisdiction [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
Other Cash Deposits [Member]
Other Temporary Investments
Cost		17,000,000.0		17,000,000.0		13,900,000
Other Short-term Investments		17,000,000.0		17,000,000.0		13,900,000
Other Cash Deposits [Member] | Gain [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments				0		0
Other Cash Deposits [Member] | Loss [Member]
Other Temporary Investments
Unrealized Gain (Loss) on Investments				0		0
Other Cash Deposits [Member] | Other [Member]
Other Temporary Investments
Other Short-term Investments	[5]	17,000,000.0		17,000,000.0		13,900,000
AEP Texas Inc. [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		6,479,400,000		6,479,400,000		5,889,800,000
Long Term Debt, Fair Value		6,112,100,000		6,112,100,000		5,400,700,000
AEP Transmission Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,862,300,000		5,862,300,000		5,414,400,000
Long Term Debt, Fair Value		5,288,500,000		5,288,500,000		4,796,900,000
Appalachian Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,659,200,000		5,659,200,000		5,588,300,000
Long Term Debt, Fair Value		5,582,500,000		5,582,500,000		5,390,100,000
Indiana Michigan Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,517,500,000		3,517,500,000		3,499,400,000
Long Term Debt, Fair Value		3,363,400,000		3,363,400,000		3,291,600,000
Nuclear Trust Fund Investments
Fair Value		4,425,800,000		4,425,800,000		3,860,200,000
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments				2,389,000,000	2,182,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		4,425,800,000		4,425,800,000		3,860,200,000
Indiana Michigan Power Co [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		10,600,000		10,600,000		9,000,000.0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		10,600,000		10,600,000		9,000,000.0
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Securities Activity Within Decommissioning and SNF Trusts
Payments to Acquire Investments		1,201,900,000	949,500,000	2,389,000,000	2,182,800,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		401,200,000		401,200,000
After 1 year through 5 years		600,800,000		600,800,000
After 5 years through 10 years		249,700,000		249,700,000
After 10 years		336,100,000		336,100,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,500,000,000		1,500,000,000		1,400,000,000
Adjusted Cost of Domestic Equity Securities		541,000,000		541,000,000		568,000,000
Other than Temporary Impairment Losses, Investments				(19,500,000)		(41,800,000)
Proceeds from Sale of Other Investments		1,181,900,000	933,000,000.0	2,336,000,000	2,139,300,000
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(2,200,000)		(2,200,000)		(10,000,000.0)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		2,320,300,000		2,320,300,000		1,902,900,000
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] | Gain [Member]
Securities Activity Within Decommissioning and SNF Trusts
Realized Investment Gains (Losses)		108,400,000	36,800,000	118,700,000	91,600,000
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] | Loss [Member]
Securities Activity Within Decommissioning and SNF Trusts
Gain (Loss) on Investments		700,000	$ 7,700,000	6,100,000	$ 20,000,000.0
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,587,800,000		1,587,800,000		1,406,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,587,800,000		1,587,800,000		1,406,800,000
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
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				(19,500,000)		(41,800,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(1,900,000)		(1,900,000)		(9,100,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		49,300,000		49,300,000		33,400,000
Indiana Michigan Power Co [Member] | Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[3]	2,811,800,000		2,811,800,000		2,436,600,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[3]	2,811,800,000		2,811,800,000		2,436,600,000
Indiana Michigan Power Co [Member] | Domestic [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value	[3]	0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[3]	0		0		0
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		(300,000)		(300,000)		(900,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		2,271,000,000		2,271,000,000		1,869,500,000
Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	26,200,000		26,200,000		16,800,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	26,200,000		26,200,000		16,800,000
Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	10,600,000		10,600,000		9,000,000.0
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	10,600,000		10,600,000		9,000,000.0
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		1,370,500,000		1,370,500,000		1,273,000,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,370,500,000		1,370,500,000		1,273,000,000
Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
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				(22,500,000)		(33,200,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(100,000)		(100,000)		(3,900,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		42,000,000.0		42,000,000.0		28,600,000
Indiana Michigan Power Co [Member] | Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		215,600,000		215,600,000		132,100,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		215,600,000		215,600,000		132,100,000
Indiana Michigan Power Co [Member] | Corporate Debt [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
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				3,000,000.0		(8,600,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(1,800,000)		(1,800,000)		(5,200,000)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		7,300,000		7,300,000		4,800,000
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		1,700,000		1,700,000		1,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,700,000		1,700,000		1,700,000
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member] | Other [Member]
Nuclear Trust Fund Investments
Fair Value		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Fair Value		0		0		0
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		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
Ohio Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,715,000,000		3,715,000,000		3,366,800,000
Long Term Debt, Fair Value		3,389,600,000		3,389,600,000		2,992,100,000
Public Service Co Of Oklahoma [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,385,400,000		2,385,400,000		2,384,600,000
Long Term Debt, Fair Value		2,210,900,000		2,210,900,000		2,154,300,000
Southwestern Electric Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,648,700,000		3,648,700,000		3,646,900,000
Long Term Debt, Fair Value		$ 3,329,100,000		$ 3,329,100,000		$ 3,209,700,000

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

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

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

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

[5] Amounts in “Other’’ column primarily represent cash deposits in bank accounts with financial institutions or third-parties.  Level 1 and Level 2 amounts primarily represent investments in money market funds.