Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020	Dec. 31, 2019
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		$ 33,454.5	[1],[2],[3]	$ 31,072.5	$ 26,725.5
Long-term Debt, Fair Value	[5]	37,564.7	[4]	37,457.0
Other Temporary Investments
Cost		232.0		214.9
Gross Unrealized Gains		36.4		31.5
Gross Unrealized Losses		0.0		0.0
Fair Value		268.4		246.4
Debt and Equity Securities Within Other Temporary Investments
Proceeds From Investment Sales		15.0		50.9	21.2
Purchases of Investments		26.9		41.6	45.0
Gross Realized Gains on Investment Sales		3.6		3.8	0.0
Gross Realized Losses on Investment Sales		0.0		0.2	0.4
Nuclear Trust Fund Investments
Fair Value		3,867.0		3,306.7
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,867.0		3,306.7
Fair Value Measurements (Textuals)
Liabilities Held for Sale		1,880.9		0.0
Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,974.7		1,509.8
Other-Than-Temporary Impairments		(10.1)		(9.2)
Securities Activity Within the Decommissioning and SNF Trusts
Proceeds from Investment Sales		1,886.4		1,593.4	1,473.0
Purchases of Investments		1,928.2		1,637.2	1,531.0
Gross Realized Gains on Investment Sales		103.2		26.4	76.5
Gross Realized Losses on Investment Sales		16.5		26.1	24.3
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		302.4
After 1 year through 5 years		431.2
After 5 years through 10 years		227.7
After 10 years		279.1
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,200.0		1,100.0
Adjusted Cost of Domestic Equity Securities		641.0		654.0
AEP Texas Inc. [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,180.8		4,820.4
Long-term Debt, Fair Value		5,663.8		5,682.6
AEP Transmission Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		4,343.9		3,948.5	3,427.3
Long-term Debt, Fair Value		4,968.2		4,984.3
Fair Value Measurements (Textuals)
Liabilities Held for Sale		27.6		0.0
Appalachian Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		4,938.9		4,834.1
Long-term Debt, Fair Value		6,037.1		6,391.8
Indiana Michigan Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,195.0		3,029.9
Long-term Debt, Fair Value		3,748.0		3,775.3
Nuclear Trust Fund Investments
Fair Value		3,867.0		3,306.7
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,867.0		3,306.7
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,974.7		1,509.8
Other-Than-Temporary Impairments		(10.1)		(9.2)
Securities Activity Within the Decommissioning and SNF Trusts
Proceeds from Investment Sales		1,886.4		1,593.4	1,473.0
Purchases of Investments		1,928.2		1,637.2	1,531.0
Gross Realized Gains on Investment Sales		103.2		26.4	76.5
Gross Realized Losses on Investment Sales		16.5		26.1	$ 24.3
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		302.4
After 1 year through 5 years		431.2
After 5 years through 10 years		227.7
After 10 years		279.1
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,200.0		1,100.0
Adjusted Cost of Domestic Equity Securities		641.0		654.0
Ohio Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,968.5		2,430.2
Long-term Debt, Fair Value		3,437.5		3,154.9
Public Service Co Of Oklahoma [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		1,913.5		1,373.8
Long-term Debt, Fair Value		2,163.7		1,732.1
Southwestern Electric Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,395.2		2,636.4
Long-term Debt, Fair Value		3,792.9		3,210.1
Cash [Member]
Other Temporary Investments
Cost	[6]	48.0		45.6
Gross Unrealized Gains	[6]	0.0		0.0
Gross Unrealized Losses	[6]	0.0		0.0
Fair Value	[6]	48.0		45.6
Other Cash Deposits [Member]
Other Temporary Investments
Cost		10.0		22.7
Gross Unrealized Gains		0.0		0.0
Gross Unrealized Losses		0.0		0.0
Fair Value	[7]	10.0		22.7
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost	[8]	154.3		120.7
Gross Unrealized Gains	[8]	0.5		2.8
Gross Unrealized Losses	[8]	0.0		0.0
Fair Value	[8]	154.8		123.5
Mutual Funds Equity [Member]
Other Temporary Investments
Cost		19.7		25.9
Gross Unrealized Gains		35.9		28.7
Gross Unrealized Losses		0.0		0.0
Fair Value		55.6		54.6
Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,240.4		1,226.2
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,240.4		1,226.2
Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		73.4		109.0
Other-Than-Temporary Impairments		(10.1)		(9.2)
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments
Fair Value		1,240.4		1,226.2
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,240.4		1,226.2
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		73.4		109.0
Other-Than-Temporary Impairments		(10.1)		(9.2)
Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[9]	2,541.9		2,054.7
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[9]	2,541.9		2,054.7
Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Unrealized Gain on Securities		1,900.0		1,400.0
Unrealized Loss on Securities		4.0		9.0
Nuclear Trust Fund Investments
Gross Unrealized Gains	[10]	1,901.3		1,400.8
Other-Than-Temporary Impairments		0.0		0.0
Domestic [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments
Fair Value	[9]	2,541.9		2,054.7
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[9]	2,541.9		2,054.7
Domestic [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Unrealized Gain on Securities		1,900.0		1,400.0
Unrealized Loss on Securities		4.0		9.0
Nuclear Trust Fund Investments
Gross Unrealized Gains	[10]	1,901.3		1,400.8
Other-Than-Temporary Impairments		0.0		0.0
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[11]	84.7		25.8
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[11]	84.7		25.8
Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0.0		0.0
Other-Than-Temporary Impairments		0.0		0.0
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments
Fair Value	[11]	84.7		25.8
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[11]	84.7		25.8
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0.0		0.0
Other-Than-Temporary Impairments		0.0		0.0
US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments
Fair Value		1,156.4		1,025.6
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,156.4		1,025.6
US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		66.3		98.5
Other-Than-Temporary Impairments		(7.9)		(7.1)
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments
Fair Value		1,156.4		1,025.6
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,156.4		1,025.6
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		66.3		98.5
Other-Than-Temporary Impairments		(7.9)		(7.1)
Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		76.7		86.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value		76.7		86.3
Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		6.7		9.6
Other-Than-Temporary Impairments		(2.1)		(1.7)
Corporate Debt [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments
Fair Value		76.7		86.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value		76.7		86.3
Corporate Debt [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		6.7		9.6
Other-Than-Temporary Impairments		(2.1)		(1.7)
State and Local Jurisdiction
Nuclear Trust Fund Investments
Fair Value		7.3		114.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value		7.3		114.3
State and Local Jurisdiction | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0.4		0.9
Other-Than-Temporary Impairments		(0.1)		(0.4)
State and Local Jurisdiction | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments
Fair Value		7.3		114.3
Contractual Maturities, Fair Value of Debt Securities
Fair Value		7.3		114.3
State and Local Jurisdiction | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		0.4		0.9
Other-Than-Temporary Impairments		(0.1)		(0.4)
Equity units [Member]
Book Values and Fair Values of Long - term Debt
Long-term Debt, Fair Value		1,700.0		$ 1,700.0
Held For Sale [Member]
Fair Value Measurements (Textuals)
Liabilities Held for Sale		1,100.0
Fair Value Held for Sale [Member]
Fair Value Measurements (Textuals)
Liabilities Held for Sale		$ 1,200.0

[1] 2021 amount excludes $1.1 billion of Total Long-term Debt Outstanding classified as Liabilities Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[2] Amount excludes $1.1 billion of Total Long-term Debt Outstanding classified as Liabilities Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 7 for additional information

[3] The 2021 book value amount excludes Long-term Debt of $1.1 billion classified as Liabilities Held for Sale on the balance sheets. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[4] The 2021 fair value amount excludes Long-term Debt of $1.2 billion related to KPCo. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[5] The fair value amounts include debt related to AEP’s Equity Units and had a fair value of $1.7 billion and $1.7 billion as of December 31, 2021 and 2020, respectively. See “Equity Units” section of Note 14 for additional information.

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

[7] 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.

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

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

[10] Amount reported as Gross Unrealized Gains includes unrealized gains of $1.9 billion and $1.4 billion and unrealized losses of $4 million and $9 million as of December 31, 2021 and 2020, respectively.

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