Fair Value Assets and Liabilities (Details) - USD ($)		3 Months Ended
		Mar. 31, 2021		Mar. 31, 2020	Dec. 31, 2020
Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		$ 11,700,000			$ 10,500,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		8,200,000			9,000,000.0
Total Assets		(106,900,000)			(199,000,000.0)
Risk Management Assets
Risk Management Assets		(126,800,000)			(218,500,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities		(131,500,000)			(221,900,000)
Other Short-term Investments		249,900,000			246,400,000
Spent Nuclear Fuel and Decommissioning Trusts		3,414,300,000			3,306,700,000
Total Assets		4,057,800,000			3,921,800,000
Risk Management Assets		336,900,000			336,900,000
Risk Management Liabilities		312,100,000			311,600,000
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		113,300,000		$ 109,900,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	[1],[2]	19,800,000		900,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	(21,300,000)		10,900,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	3,100,000		(4,100,000)
Settlements		(47,900,000)		(59,200,000)
Transfers into Level 3	[4],[5]	500,000		(500,000)
Transfers out of Level 3	[5]	(33,000,000.0)		5,300,000
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	7,300,000		(20,700,000)
Ending Balance		41,800,000		42,500,000
Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		238,200,000			235,900,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		2,247,000,000.0			2,071,500,000
Total Assets		2,486,400,000			2,308,300,000
Risk Management Assets
Risk Management Assets		1,200,000			900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		800,000			900,000
Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,159,100,000			1,226,200,000
Total Assets		1,480,800,000			1,524,400,000
Risk Management Assets
Risk Management Assets		265,000,000.0			298,200,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		287,100,000			357,800,000
Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Total Assets		197,500,000			288,100,000
Risk Management Assets
Risk Management Assets		197,500,000			256,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		155,700,000			174,800,000
2021 [Member] | Level 2 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		(3,000,000)
2021 [Member] | Level 3 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		23,000,000			47,000,000
2022 - 2024 [Member] | Level 2 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		11,000,000			3,000,000
2022 - 2024 [Member] | Level 3 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		32,000,000			37,000,000
2025 - 2026 [Member] | Level 2 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		17,000,000			11,000,000
2025 - 2026 [Member] | Level 3 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		8,000,000			14,000,000
2027 - 2033 [Member] | Level 2 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		10,000,000			1,000,000
2027 - 2033 [Member] | Level 3 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		(21,000,000)			(13,000,000)
Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7]	(94,800,000)	[8]		(190,000,000.0)	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	(99,500,000)	[8]		(193,400,000)	[9]
Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7]	319,100,000	[8]		322,100,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	236,800,000	[8]		218,900,000	[9]
Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7]	1,200,000	[8]		900,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	800,000	[8]		900,000	[9]
Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7]	217,900,000	[8]		258,800,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	182,700,000	[8]		244,200,000	[9]
Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7]	194,800,000	[8]		252,400,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	152,800,000	[8]		167,200,000	[9]
Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		178,500,000			213,500,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		151,700,000			169,700,000
Energy Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	0.10			5.33
Energy Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	98.66			100.47
Energy Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	28.85			32.73
Natural Gas Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		900,000			1,700,000
Natural Gas Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[12]	2.24			2.18
Natural Gas Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[12]	2.92			2.77
Natural Gas Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[11],[12]	2.50			2.40
FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		19,000,000.0			42,800,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		3,100,000			3,400,000
FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	(13.61)			(15.08)
FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	9.08			9.66
FTRs [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	0.02			0.19
Commodity Hedges [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7]	(32,000,000.0)			(28,500,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	(32,000,000.0)			(28,500,000)
Commodity Hedges [Member]
Risk Management Assets
Risk Management Assets	[7]	15,100,000			9,800,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	37,900,000			85,200,000
Commodity Hedges [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	0			0
Commodity Hedges [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7]	44,400,000			34,400,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	67,000,000.0			106,100,000
Commodity Hedges [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7]	2,700,000			3,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	2,900,000			7,600,000
Interest Rate [Member] | Other [Member]
Risk Management Assets
Risk Management Assets					0
Interest Rate [Member]
Risk Management Assets
Risk Management Assets					2,400,000
Interest Rate [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets					0
Interest Rate [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets					2,400,000
Interest Rate [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets					0
Fair Value Hedges [Member] | Other [Member]
Risk Management Assets
Risk Management Assets		0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0
Fair Value Hedges [Member]
Risk Management Assets
Risk Management Assets		2,700,000			2,600,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		37,400,000			4,100,000
Fair Value Hedges [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets		0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0
Fair Value Hedges [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets		2,700,000			2,600,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		37,400,000			4,100,000
Fair Value Hedges [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0
Other Investments | Other [Member]
Risk Management Assets
Risk Management Assets	[13]	0			0
Other Investments
Risk Management Assets
Risk Management Assets	[13]	56,700,000			31,800,000
Other Investments | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[13]	0			0
Other Investments | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[13]	56,700,000			0
Other Investments | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[13]	0			31,800,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
Other Investments | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[14]				0.10
Other Investments | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[14]				0.20
Other Investments | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[14]				0.15
Interest Rate Foreign Currency Hedges | Other [Member]
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
Interest Rate Foreign Currency Hedges
Liabilities, Fair Value Disclosure
Risk Management Liabilities					3,400,000
Interest Rate Foreign Currency Hedges | Level 1 [Member]
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
Interest Rate Foreign Currency Hedges | Level 2 [Member]
Liabilities, Fair Value Disclosure
Risk Management Liabilities					3,400,000
Interest Rate Foreign Currency Hedges | Level 3 [Member]
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
AEP Texas Inc. [Member] | Other [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		(800,000)			(400,000)
AEP Texas Inc. [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		39,300,000			28,700,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		39,300,000			28,700,000
AEP Texas Inc. [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		39,300,000			28,700,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		39,300,000			28,700,000
AEP Texas Inc. [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		800,000			400,000
AEP Texas Inc. [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		0			0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7]	(800,000)			(400,000)
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7]	800,000			400,000
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0
Appalachian Power Co [Member] | Other [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		(10,000,000.0)			(19,200,000)
Risk Management Assets
Risk Management Assets					(19,200,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities					(18,800,000)
Appalachian Power Co [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		11,600,000			16,900,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		18,500,000			39,400,000
Risk Management Assets
Risk Management Assets					22,500,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities					4,700,000
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		19,300,000		37,700,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	[1],[2]	2,100,000		(9,200,000)
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	0		0
Settlements		(15,600,000)		(21,900,000)
Transfers into Level 3	[4],[5]	0		0
Transfers out of Level 3	[5]	0		700,000
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	800,000		(700,000)
Ending Balance		6,600,000		6,600,000
Appalachian Power Co [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		11,600,000			16,900,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		11,600,000			16,900,000
Risk Management Assets
Risk Management Assets					0
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
Appalachian Power Co [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		9,800,000			21,800,000
Risk Management Assets
Risk Management Assets					21,800,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities					22,900,000
Appalachian Power Co [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		7,100,000			19,900,000
Risk Management Assets
Risk Management Assets		7,100,000			19,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		500,000			600,000
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(10,000,000.0)			(19,200,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	(9,500,000)			(18,800,000)
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	6,900,000			20,100,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	200,000			1,300,000
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	9,800,000			19,400,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	9,200,000			19,500,000
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	7,100,000			19,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	500,000			600,000
Appalachian Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		400,000			1,000,000.0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		500,000			600,000
Appalachian Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	10.92			10.84
Appalachian Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	44.29			41.09
Appalachian Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	25.13			25.08
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		6,700,000			18,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	0.08			0.04
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	4.99			5.61
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	0.99			1.13
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges | Other [Member]
Risk Management Assets
Risk Management Assets					0
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges
Risk Management Assets
Risk Management Assets					2,400,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities					3,400,000
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges | Level 1 [Member]
Risk Management Assets
Risk Management Assets					0
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges | Level 2 [Member]
Risk Management Assets
Risk Management Assets					2,400,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities					3,400,000
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges | Level 3 [Member]
Risk Management Assets
Risk Management Assets					0
Liabilities, Fair Value Disclosure
Risk Management Liabilities					0
Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		8,200,000			9,000,000.0
Total Assets		2,000,000.0			(4,900,000)
Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		3,414,300,000			3,306,700,000
Total Assets		3,415,200,000			3,310,400,000
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		2,100,000		5,800,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	[1],[2]	300,000		200,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	0		0
Settlements		(1,400,000)		(4,000,000.0)
Transfers into Level 3	[4],[5]	0		0
Transfers out of Level 3	[5]	0		400,000
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	(300,000)		(300,000)
Ending Balance		700,000		2,100,000
Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		2,247,000,000.0			2,071,500,000
Total Assets		2,247,000,000.0			2,071,500,000
Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,159,100,000			1,226,200,000
Total Assets		1,165,100,000			1,241,300,000
Indiana Michigan Power Co [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Total Assets		1,100,000			2,500,000
Risk Management Assets
Risk Management Assets		1,100,000			2,500,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		400,000			400,000
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(6,200,000)			(13,900,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	(6,300,000)			(12,200,000)
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	900,000			3,700,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	200,000			200,000
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	6,000,000.0			15,100,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	6,100,000			12,000,000.0
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	1,100,000			2,500,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	400,000			400,000
Indiana Michigan Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		300,000			600,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		300,000			300,000
Indiana Michigan Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	10.92			10.84
Indiana Michigan Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	44.29			41.09
Indiana Michigan Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	25.13			25.08
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		800,000			1,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		100,000			100,000
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	(2.29)			(1.96)
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	3.66			3.69
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	0.33			0.33
Ohio Power Co [Member]
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		(110,300,000)		(103,600,000)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	[1],[2]	0		(300,000)
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	0		0
Settlements		2,700,000		2,500,000
Transfers into Level 3	[4],[5]	0		0
Transfers out of Level 3	[5]	0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	3,600,000		(19,500,000)
Ending Balance		(104,000,000.0)		(120,900,000)
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(600,000)			(300,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	104,000,000.0			110,300,000
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	600,000			300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	104,000,000.0			110,300,000
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		104,000,000.0			110,300,000
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	15.08			16.19
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	49.09			46.98
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	27.79			28.30
Public Service Co Of Oklahoma [Member]
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		10,300,000		15,800,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	[1],[2]	9,300,000		8,000,000.0
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	0		0
Settlements		(16,300,000)		(17,700,000)
Transfers into Level 3	[4],[5]	0		0
Transfers out of Level 3	[5]	0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	2,200,000		200,000
Ending Balance		5,500,000		6,300,000
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(300,000)			(200,000)
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	5,500,000			10,300,000
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	300,000			200,000
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	5,500,000			10,300,000
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		5,500,000			10,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	(13.61)			(6.93)
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	2.04			0.48
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	(3.01)			(1.93)
Southwestern Electric Power Co [Member]
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		1,600,000		1,400,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	[1],[2]	6,100,000		1,900,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	0		0
Settlements		(8,200,000)		(5,300,000)
Transfers into Level 3	[4],[5]	0		0
Transfers out of Level 3	[5]	0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	1,000,000.0		(500,000)
Ending Balance		500,000		$ (2,500,000)
Southwestern Electric Power Co [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		1,400,000			3,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		900,000			1,700,000
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(400,000)			(200,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	1,300,000			3,200,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	900,000			1,700,000
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	300,000			100,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	1,400,000			3,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	900,000			1,700,000
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		900,000			1,700,000
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[12]	2.24			2.18
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[12]	2.92			2.77
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[11],[12]	2.50			2.41
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		1,400,000			3,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	(13.61)			(6.93)
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	2.04			0.48
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	(3.01)			(1.93)
Cash [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	11,700,000			10,500,000
Cash [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16],[17]	74,600,000			68,300,000
Cash [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	62,900,000			57,800,000
Cash [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	0			0
Cash [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	0			0
Fixed Income Funds [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Fixed Income Funds [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,159,100,000			1,226,200,000
Fixed Income Funds [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Fixed Income Funds [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,159,100,000			1,226,200,000
Fixed Income Funds [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,159,100,000			1,226,200,000
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,159,100,000			1,226,200,000
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Mutual Funds Fixed Income [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0
Mutual Funds Fixed Income [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[18]	118,700,000			123,500,000
Mutual Funds Fixed Income [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		118,700,000			123,500,000
Mutual Funds Fixed Income [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0
Mutual Funds Fixed Income [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0
Mutual Funds Equity [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	0			0
Mutual Funds Equity [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	56,600,000			54,600,000
Mutual Funds Equity [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	56,600,000			54,600,000
Mutual Funds Equity [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	0			0
Mutual Funds Equity [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	0			0
Cash and Cash Equivalents [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	8,200,000			9,000,000.0
Cash and Cash Equivalents [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	47,700,000			25,800,000
Cash and Cash Equivalents [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	39,500,000			16,800,000
Cash and Cash Equivalents [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	0			0
Cash and Cash Equivalents [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	0			0
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	8,200,000			9,000,000.0
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	47,700,000			25,800,000
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	39,500,000			16,800,000
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	0			0
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	0			0
US Government Agencies Debt Securities [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
US Government Agencies Debt Securities [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		998,900,000			1,025,600,000
US Government Agencies Debt Securities [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
US Government Agencies Debt Securities [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		998,900,000			1,025,600,000
US Government Agencies Debt Securities [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		998,900,000			1,025,600,000
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		998,900,000			1,025,600,000
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Corporate Debt [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Corporate Debt [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		76,400,000			86,300,000
Corporate Debt [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Corporate Debt [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		76,400,000			86,300,000
Corporate Debt [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Corporate Debt [Member] | Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Corporate Debt [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		76,400,000			86,300,000
Corporate Debt [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Corporate Debt [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		76,400,000			86,300,000
Corporate Debt [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
State and Local Jurisdiction [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
State and Local Jurisdiction [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		83,800,000			114,300,000
State and Local Jurisdiction [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
State and Local Jurisdiction [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		83,800,000			114,300,000
State and Local Jurisdiction [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
State and Local Jurisdiction [Member] | Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
State and Local Jurisdiction [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		83,800,000			114,300,000
State and Local Jurisdiction [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
State and Local Jurisdiction [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		83,800,000			114,300,000
State and Local Jurisdiction [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0
Domestic [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			0
Domestic [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,207,500,000			2,054,700,000
Domestic [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,207,500,000			2,054,700,000
Domestic [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			0
Domestic [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			0
Domestic [Member] | Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			0
Domestic [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,207,500,000			2,054,700,000
Domestic [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,207,500,000			2,054,700,000
Domestic [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			0
Domestic [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	$ 0			$ 0

[1] Included in revenues on the statements of income.

[2] Represents the change in fair value between the beginning of the reporting period and the settlement of the risk management commodity contract.

[3] Included in cash flow hedges on the statements of comprehensive income.

[4] Represents existing assets or liabilities that were previously categorized as Level 2.

[5] Transfers are recognized based on their value at the beginning of the reporting period that the transfer occurred.

[6] Relates to the net gains (losses) of those contracts that are not reflected on the statements of income.  These net gains (losses) are recorded as regulatory assets/liabilities or accounts payable.

[7] Amounts in “Other’’ column primarily represent counterparty netting of risk management and hedging contracts and associated cash collateral under the accounting guidance for “Derivatives and Hedging.’’

[8] The March 31, 2021 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows: Level 2 matures $(3) million in 2021, $11 million in periods 2022-2024, $17 million in periods 2025-2026 and $10 million in periods 2027-2033; Level 3 matures $23 million in 2021, $32 million in periods 2022-2024, $8 million in periods 2025-2026 and $(21) million in periods 2027-2033.  Risk management commodity contracts are substantially comprised of power contracts.

[9] The December 31, 2020 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows: Level 2 matures $3 million in periods 2022-2024, $11 million in periods 2025-2026 and $1 million in periods 2027-2033; Level 3 matures $47 million in 2021, $37 million in periods 2022-2024, $14 million in periods 2025-2026 and $(13) million in periods 2027-2033.  Risk management commodity contracts are substantially comprised of power contracts.

[10] Represents market prices in dollars per MWh.

[11] The weighted average is the product of the forward market price of the underlying commodity and volume weighted by term.

[12] Represents market prices in dollars per MMBtu.

[13] See “Warrants Held in Investee” section of Note 9 for additional information.

[14] Represents percentage discount applied to the publically available share price.

[15] Substantially comprised of power contracts for the Registrant Subsidiaries.

[16] 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.

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

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

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

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