Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($)		3 Months Ended			12 Months Ended
		Mar. 31, 2022		Mar. 31, 2021	Dec. 31, 2021
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding	[1]	$ 33,864,100,000			$ 33,454,500,000
Long Term Debt, Fair Value	[2],[3]	34,144,500,000			37,564,700,000
Other Temporary Investments
Cost		230,600,000			232,000,000.0
Gross Unrealized Gains		32,300,000			36,400,000
Gross Unrealized Losses		(4,500,000)			0
Other Short-term Investments		258,400,000			268,400,000
Debt and Equity Securities Within Other Temporary Investments
Proceeds from Investment Sales		3,900,000		$ 5,500,000
Purchases of Investments		800,000		700,000
Gross Realized Gains on Investment Sales		300,000		100,000
Gross Realized Losses on Investment Sales		100,000		0
Nuclear Trust Fund Investments
Fair Value		3,678,400,000			3,867,000,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,678,400,000			3,867,000,000
Fair Value Measurements (Textuals)
Liabilities Held for Sale		1,873,700,000			1,880,900,000
Spent Nuclear Fuel and Decommissioning Trusts [Member]
Unrealized Gain on Securities		1,800,000,000			1,900,000,000
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,777,300,000			1,974,700,000
Securities Activity Within Decommissioning and SNF Trusts
Proceeds from Investment Sales		493,500,000		320,000,000.0
Purchases of Investments		507,700,000		336,900,000
Gross Realized Gains on Investment Sales		5,800,000		5,400,000
Gross Realized Losses on Investment Sales		7,200,000		4,200,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		342,300,000
After 1 year through 5 years		427,300,000
After 5 years through 10 years		232,400,000
After 10 years		244,200,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,200,000,000			1,200,000,000
Adjusted Cost of Domestic Equity Securities		647,000,000			641,000,000
Unrealized Loss on Securities		5,000,000			4,000,000
Other than Temporary Impairment Losses, Investments		(26,400,000)			(10,100,000)
Cash [Member]
Other Temporary Investments
Cost	[4]	49,900,000			48,000,000.0
Gross Unrealized Gains	[4]	0			0
Gross Unrealized Losses	[4]	0			0
Other Short-term Investments	[4]	49,900,000			48,000,000.0
Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,246,200,000			1,240,400,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,246,200,000			1,240,400,000
Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		13,800,000			73,400,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(26,400,000)			(10,100,000)
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost	[5]	151,500,000			154,300,000
Gross Unrealized Gains	[5]	0			500,000
Gross Unrealized Losses	[5]	(4,500,000)			0
Other Short-term Investments	[5]	147,000,000.0			154,800,000
Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[6]	2,410,400,000			2,541,900,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[6]	2,410,400,000			2,541,900,000
Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains	[7]	1,763,500,000			1,901,300,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		0			0
Mutual Funds Equity [Member]
Other Temporary Investments
Cost		19,700,000			19,700,000
Gross Unrealized Gains		32,300,000			35,900,000
Gross Unrealized Losses		0			0
Other Short-term Investments	[6]	52,000,000.0			55,600,000
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments
Fair Value	[8]	21,800,000			84,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[8]	21,800,000			84,700,000
Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		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		1,169,600,000			1,156,400,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,169,600,000			1,156,400,000
US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		13,500,000			66,300,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(22,300,000)			(7,900,000)
Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		69,400,000			76,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		69,400,000			76,700,000
Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		100,000			6,700,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(4,000,000.0)			(2,100,000)
State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		7,200,000			7,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		7,200,000			7,300,000
State and Local Jurisdiction [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		200,000			400,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(100,000)			(100,000)
Other Cash Deposits [Member]
Other Temporary Investments
Cost		9,500,000			10,000,000.0
Gross Unrealized Gains		0			0
Gross Unrealized Losses		0			0
Other Short-term Investments		9,500,000			10,000,000.0
AEP Texas Inc. [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		5,170,600,000			5,180,800,000
Long Term Debt, Fair Value		5,123,400,000			5,663,800,000
AEP Transmission Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		4,344,500,000			4,343,900,000
Long Term Debt, Fair Value		4,301,500,000			4,968,200,000
Fair Value Measurements (Textuals)
Liabilities Held for Sale		27,600,000			27,600,000
Appalachian Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		4,927,200,000			4,938,900,000
Long Term Debt, Fair Value		5,339,900,000			6,037,100,000
Indiana Michigan Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,171,700,000			3,195,000,000
Long Term Debt, Fair Value		3,282,600,000			3,748,000,000
Nuclear Trust Fund Investments
Fair Value		3,678,400,000			3,867,000,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		3,678,400,000			3,867,000,000
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Unrealized Gain on Securities		1,800,000,000			1,900,000,000
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,777,300,000			1,974,700,000
Securities Activity Within Decommissioning and SNF Trusts
Proceeds from Investment Sales		493,500,000		320,000,000.0
Purchases of Investments		507,700,000		336,900,000
Gross Realized Gains on Investment Sales		5,800,000		5,400,000
Gross Realized Losses on Investment Sales		7,200,000		$ 4,200,000
Contractual Maturities, Fair Value of Debt Securities
Within 1 year		342,300,000
After 1 year through 5 years		427,300,000
After 5 years through 10 years		232,400,000
After 10 years		244,200,000
Fair Value Measurements (Textuals)
Adjusted Cost of Debt Securities		1,200,000,000			1,200,000,000
Adjusted Cost of Domestic Equity Securities		647,000,000			641,000,000
Unrealized Loss on Securities		5,000,000			4,000,000
Other than Temporary Impairment Losses, Investments		(26,400,000)			(10,100,000)
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member]
Nuclear Trust Fund Investments
Fair Value		1,246,200,000			1,240,400,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,246,200,000			1,240,400,000
Indiana Michigan Power Co [Member] | Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		13,800,000			73,400,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(26,400,000)			(10,100,000)
Indiana Michigan Power Co [Member] | Domestic [Member]
Nuclear Trust Fund Investments
Fair Value	[6]	2,410,400,000			2,541,900,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[6]	2,410,400,000			2,541,900,000
Indiana Michigan Power Co [Member] | Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		1,763,500,000	[7]		1,901,300,000
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	[8]	21,800,000			84,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value	[8]	21,800,000			84,700,000
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
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		1,169,600,000			1,156,400,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		1,169,600,000			1,156,400,000
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		13,500,000			66,300,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(22,300,000)			(7,900,000)
Indiana Michigan Power Co [Member] | Corporate Debt [Member]
Nuclear Trust Fund Investments
Fair Value		69,400,000			76,700,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		69,400,000			76,700,000
Indiana Michigan Power Co [Member] | Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		100,000			6,700,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(4,000,000.0)			(2,100,000)
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments
Fair Value		7,200,000			7,300,000
Contractual Maturities, Fair Value of Debt Securities
Fair Value		7,200,000			7,300,000
Indiana Michigan Power Co [Member] | State and Local Jurisdiction [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member]
Nuclear Trust Fund Investments
Gross Unrealized Gains		200,000			400,000
Fair Value Measurements (Textuals)
Other than Temporary Impairment Losses, Investments		(100,000)			(100,000)
Ohio Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,969,000,000			2,968,500,000
Long Term Debt, Fair Value		2,965,600,000			3,437,500,000
Public Service Co Of Oklahoma [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,413,600,000			1,913,500,000
Long Term Debt, Fair Value		2,412,600,000			2,163,700,000
Southwestern Electric Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,394,100,000			3,395,200,000
Long Term Debt, Fair Value		3,342,400,000			3,792,900,000
Risk Management Commodity Contracts [Member]
Fair Value Measurements (Textuals)
Liabilities Held for Sale					100,000
Equity Units [Member]
Book Values and Fair Values of Long - term Debt
Long Term Debt, Fair Value		950,000,000			1,700,000,000
Held For Sale
Fair Value Measurements (Textuals)
Liabilities Held for Sale		1,100,000,000			1,100,000,000
Fair Value Held for Sale [Member]
Fair Value Measurements (Textuals)
Liabilities Held for Sale		$ 1,100,000,000			$ 1,200,000,000

[1] The book value amounts exclude Long-term Debt of $1.1 billion and $1.1 billion as of March 31, 2022 and December 31, 2021, respectively, classified as Liabilities Held for Sale on the balance sheets. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

[2] The fair value amounts exclude Long-term Debt of $1.1 billion and $1.2 billion as of March 31, 2022 and December 31, 2021, respectively, related to KPCo. See “Disposition of KPCo and KTCo” section of Note 6 for additional information.

[3] The fair value amounts include debt related to AEP’s Equity Units and had a fair value of $950 million and $1.7 billion as of March 31, 2022 and December 31, 2021, respectively. See “Equity Units” section of Note 12 for additional information.

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

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

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

[7] Amount reported as Gross Unrealized Gains includes unrealized gains of $1.8 billion and $1.9 billion and unrealized losses of $5 million and $4 million as of March 31, 2022 and December 31, 2021, respectively.

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