Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		$ 40,143.2	$ 36,801.0
Long-term Debt, Fair Value	[1]	37,325.7	35,915.9
Other Temporary Investments
Cost		243.5	223.6
Gross Unrealized Gains		25.9	19.4
Gross Unrealized Losses		(6.2)	(8.3)
Fair Value		263.2	234.7
Debt and Equity Securities Within Other Temporary Investments
Proceeds From Investment Sales		7.6	30.2	$ 15.0
Purchases of Investments		18.5	18.8	26.9
Gross Realized Gains on Investment Sales		1.1	6.1	3.6
Gross Realized Losses on Investment Sales		0.3	1.3	0.0
Nuclear Trust Fund Investments
Fair Value		3,860.2	3,341.2
Securities Activity Within the Decommissioning and SNF Trusts
Payments to Acquire Investments		2,863.6	2,784.2	1,955.1
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,860.2	3,341.2
Spent Nuclear Fuel and Decommissioning Trusts [Member]
Securities Activity Within the Decommissioning and SNF Trusts
Payments to Acquire Investments		2,845.1	2,765.4	1,928.2
Realized Investment Gains (Losses)		99.0	52.4	103.2
Gain (Loss) on Investments		26.6	42.6	16.5
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		359.6
After 1 year through 5 years		597.6
After 5 years through 10 years		180.7
After 10 years		268.9
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,400.0	1,200.0
Adjusted Cost of Domestic Equity Securities		568.0	654.0
Proceeds from Sale of Other Investments		2,787.5	2,713.6	1,886.4
Realized Investment Gains (Losses)		99.0	52.4	103.2
Gain (Loss) on Investments		26.6	42.6	16.5
Other than Temporary Impairment Losses, Investments		(41.8)	(28.5)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,902.9	1,496.3
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(10.0)	(29.0)
Cash [Member]
Other Temporary Investments
Cost	[2]	48.9	47.1
Gross Unrealized Gains	[2]	0.0	0.0
Gross Unrealized Losses	[2]	0.0	0.0
Fair Value	[2]	48.9	47.1
Other Cash Deposits [Member]
Other Temporary Investments
Cost		13.9	9.0
Gross Unrealized Gains		0.0	0.0
Gross Unrealized Losses		0.0	0.0
Fair Value		13.9	9.0
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost	[3]	165.9	152.4
Gross Unrealized Gains	[3]	0.0	0.0
Gross Unrealized Losses	[3]	(6.2)	(8.3)
Fair Value	[3]	159.7	144.1
Mutual Funds Equity [Member]
Other Temporary Investments
Cost		14.8	15.1
Gross Unrealized Gains		25.9	19.4
Gross Unrealized Losses		0.0	0.0
Fair Value		40.7	34.5
Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	2,436.6	2,131.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	2,436.6	2,131.3
Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0.0	0.0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,869.5	1,483.7
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(0.9)	(6.4)
Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,406.8	1,188.7
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,406.8	1,188.7
Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(41.8)	(28.5)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		33.4	12.6
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(9.1)	(22.6)
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[5]	16.8	21.2
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[5]	16.8	21.2
Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0.0	0.0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0.0	0.0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0.0	0.0
US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments
Fair Value		1,273.0	1,123.8
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,273.0	1,123.8
US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(33.2)	(18.8)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		28.6	11.8
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(3.9)	(14.9)
Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		132.1	61.6
Contractual Maturities, Fair Value of Debt Securities
Fair Value		132.1	61.6
Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(8.6)	(9.6)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		4.8	0.7
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(5.2)	(7.7)
State and Local Jurisdiction
Nuclear Trust Fund Investments
Fair Value		1.7	3.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1.7	3.3
State and Local Jurisdiction | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0.0	(0.1)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0.0	0.1
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0.0	0.0
AEP Texas Inc. [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,889.8	5,657.8
Long-term Debt, Fair Value		5,400.7	5,045.8
AEP Transmission Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,414.4	4,782.8
Long-term Debt, Fair Value		4,796.9	3,940.5
Appalachian Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,588.3	5,410.5
Long-term Debt, Fair Value		5,390.1	5,079.2
Indiana Michigan Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,499.4	3,260.8
Long-term Debt, Fair Value		3,291.6	2,929.0
Nuclear Trust Fund Investments
Fair Value		3,860.2	3,341.2
Securities Activity Within the Decommissioning and SNF Trusts
Payments to Acquire Investments		2,845.1	2,765.4	1,928.2
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,860.2	3,341.2
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Securities Activity Within the Decommissioning and SNF Trusts
Payments to Acquire Investments		2,845.1	2,765.4	1,928.2
Realized Investment Gains (Losses)		99.0	52.4	103.2
Gain (Loss) on Investments		26.6	42.6	16.5
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		359.6
After 1 year through 5 years		597.6
After 5 years through 10 years		180.7
After 10 years		268.9
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,400.0	1,200.0
Adjusted Cost of Domestic Equity Securities		568.0	654.0
Proceeds from Sale of Other Investments		2,787.5	2,713.6	1,886.4
Realized Investment Gains (Losses)		99.0	52.4	103.2
Gain (Loss) on Investments		26.6	42.6	$ 16.5
Other than Temporary Impairment Losses, Investments		(41.8)	(28.5)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,902.9	1,496.3
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(10.0)	(29.0)
Indiana Michigan Power Co [Member] | Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[4]	2,436.6	2,131.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[4]	2,436.6	2,131.3
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	0.0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		1,869.5	1,483.7
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(0.9)	(6.4)
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,406.8	1,188.7
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,406.8	1,188.7
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		(41.8)	(28.5)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		33.4	12.6
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(9.1)	(22.6)
Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[5]	16.8	21.2
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[5]	16.8	21.2
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	0.0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0.0	0.0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0.0	0.0
Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments
Fair Value		1,273.0	1,123.8
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,273.0	1,123.8
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		(33.2)	(18.8)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		28.6	11.8
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(3.9)	(14.9)
Indiana Michigan Power Co [Member] | Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		132.1	61.6
Contractual Maturities, Fair Value of Debt Securities
Fair Value		132.1	61.6
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		(8.6)	(9.6)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		4.8	0.7
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		(5.2)	(7.7)
Indiana Michigan Power Co [Member] | State and Local Jurisdiction
Nuclear Trust Fund Investments
Fair Value		1.7	3.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1.7	3.3
Indiana Michigan Power Co [Member] | State and Local Jurisdiction | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0.0	(0.1)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0.0	0.1
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0.0	0.0
Ohio Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,366.8	2,970.3
Long-term Debt, Fair Value		2,992.1	2,516.6
Public Service Co Of Oklahoma [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,384.6	1,912.8
Long-term Debt, Fair Value		2,154.3	1,635.8
Southwestern Electric Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,646.9	3,391.6
Long-term Debt, Fair Value		3,209.7	2,870.9
Equity units [Member]
Book Values and Fair Values of Long - term Debt
Long-term Debt, Fair Value		$ 0.0	$ 877.0

[1] The fair value amounts include debt related to AEP’s Equity Units and had a fair value of $0 million and $877 million as of December 31, 2023 and 2022, respectively. See “Equity Units” section of Note 14 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.