Fair Value Assets and Liabilities (Details) - USD ($)		3 Months Ended			6 Months Ended
		Jun. 30, 2021		Jun. 30, 2020	Jun. 30, 2021		Jun. 30, 2020	Dec. 31, 2020
Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		$ 21,100,000			$ 21,100,000			$ 10,500,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		7,600,000			7,600,000			9,000,000.0
Total Assets		(401,300,000)			(401,300,000)			(199,000,000.0)
Risk Management Assets
Risk Management Assets		(430,000,000.0)			(430,000,000.0)			(218,500,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities		(337,000,000.0)			(337,000,000.0)			(221,900,000)
Other Short-term Investments		268,700,000			268,700,000			246,400,000
Spent Nuclear Fuel and Decommissioning Trusts		3,612,400,000			3,612,400,000			3,306,700,000
Total Assets		4,409,600,000			4,409,600,000			3,921,800,000
Risk Management Assets		456,000,000.0			456,000,000.0			336,900,000
Risk Management Liabilities		264,100,000			264,100,000			311,600,000
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		41,800,000		$ 42,500,000	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]	18,600,000		39,100,000	78,300,000		38,200,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	(10,600,000)		(17,200,000)	(66,800,000)		(6,400,000)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	15,400,000		22,000,000.0	18,500,000		18,300,000
Settlements		(34,500,000)		(54,700,000)	(110,600,000)		(113,700,000)
Transfers into Level 3	[4],[5]	(800,000)			(200,000)		(600,000)
Transfers out of Level 3	[5]	(19,100,000)		(200,000)	(25,600,000)		4,300,000
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	90,400,000		80,100,000	94,300,000		61,600,000
Ending Balance		101,200,000		111,600,000	101,200,000		111,600,000
Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		247,600,000			247,600,000			235,900,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		2,302,800,000			2,302,800,000			2,071,500,000
Total Assets		2,555,200,000			2,555,200,000			2,308,300,000
Risk Management Assets
Risk Management Assets		4,800,000			4,800,000			900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		2,500,000			2,500,000			900,000
Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0			0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,302,000,000.0			1,302,000,000.0			1,226,200,000
Total Assets		2,014,500,000			2,014,500,000			1,524,400,000
Risk Management Assets
Risk Management Assets		640,000,000.0			640,000,000.0			298,200,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		458,600,000			458,600,000			357,800,000
Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0			0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0			0
Total Assets		241,200,000			241,200,000			288,100,000
Risk Management Assets
Risk Management Assets		241,200,000			241,200,000			256,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		140,000,000.0			140,000,000.0			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		11,000,000			11,000,000
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		96,000,000			96,000,000			47,000,000
2022 - 2024 [Member] | Level 1 [Member]
Fair Value Measurements 1 (Textuals)
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities		2,000,000			2,000,000
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		37,000,000			37,000,000			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		12,000,000			12,000,000			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		22,000,000			22,000,000			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		4,000,000			4,000,000			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		13,000,000			13,000,000			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		(27,000,000)			(27,000,000)			(13,000,000)
Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7]	(400,100,000)	[8]		(400,100,000)	[8]		(190,000,000.0)	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	(307,100,000)	[8]		(307,100,000)	[8]		(193,400,000)	[9]
Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7]	307,100,000	[8]		307,100,000	[8]		322,100,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	229,700,000	[8]		229,700,000	[8]		218,900,000	[9]
Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7]	4,800,000	[8]		4,800,000	[8]		900,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	2,500,000	[8]		2,500,000	[8]		900,000	[9]
Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7]	478,100,000	[8]		478,100,000	[8]		258,800,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	395,200,000	[8]		395,200,000	[8]		244,200,000	[9]
Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7]	224,300,000	[8]		224,300,000	[8]		252,400,000	[9]
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	139,100,000	[8]		139,100,000	[8]		167,200,000	[9]
Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		141,700,000			141,700,000			213,500,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		134,800,000			134,800,000			169,700,000
Energy Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	0.05			0.05			5.33
Energy Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	96.20			96.20			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]	31.99			31.99			32.73
Natural Gas Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		3,100,000			3,100,000			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0			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]	2.28			2.28			2.18
Natural Gas Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[12]	3.82			3.82			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]	3.14			3.14			2.40
FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		96,400,000			96,400,000			42,800,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		5,200,000			5,200,000			3,400,000
FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	(18.06)			(18.06)			(15.08)
FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	12.15			12.15			9.66
FTRs [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	0.22			0.22			0.19
Commodity Hedges [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7]	(29,900,000)			(29,900,000)			(28,500,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	(29,900,000)			(29,900,000)			(28,500,000)
Commodity Hedges [Member]
Risk Management Assets
Risk Management Assets	[7]	145,700,000			145,700,000			9,800,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	6,000,000.0			6,000,000.0			85,200,000
Commodity Hedges [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	0			0			0
Commodity Hedges [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7]	158,700,000			158,700,000			34,400,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	35,000,000.0			35,000,000.0			106,100,000
Commodity Hedges [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7]	16,900,000			16,900,000			3,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7]	900,000			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			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0			0
Fair Value Hedges [Member]
Risk Management Assets
Risk Management Assets		3,200,000			3,200,000			2,600,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		28,400,000			28,400,000			4,100,000
Fair Value Hedges [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets		0			0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0			0
Fair Value Hedges [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets		3,200,000			3,200,000			2,600,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		28,400,000			28,400,000			4,100,000
Fair Value Hedges [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		0			0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0			0
Other Investments | Other [Member]
Risk Management Assets
Risk Management Assets	[13]	0			0			0
Other Investments
Risk Management Assets
Risk Management Assets	[13]	72,500,000			72,500,000			31,800,000
Other Investments | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[13]	0			0			0
Other Investments | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[13]	72,500,000			72,500,000			0
Other Investments | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[13]	0			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			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		(1,100,000)			(1,100,000)			(400,000)
AEP Texas Inc. [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		27,900,000			27,900,000			28,700,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		27,900,000			27,900,000			28,700,000
AEP Texas Inc. [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		27,900,000			27,900,000			28,700,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		27,900,000			27,900,000			28,700,000
AEP Texas Inc. [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		1,100,000			1,100,000			400,000
AEP Texas Inc. [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		0			0			0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7]	(1,100,000)			(1,100,000)			(400,000)
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0			0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0			0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7]	1,100,000			1,100,000			400,000
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7]	0			0			0
Appalachian Power Co [Member] | Other [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0			0			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		(27,200,000)			(27,200,000)			(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		19,100,000			19,100,000			16,900,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		56,200,000			56,200,000			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		6,600,000		6,600,000	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]	6,200,000		23,500,000	38,900,000		12,900,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0	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	0		0
Settlements		(13,000,000.0)		(28,900,000)	(58,400,000)		(50,800,000)
Transfers into Level 3	[4],[5]	0			0		0
Transfers out of Level 3	[5]	0		0	0		700,000
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	36,800,000		35,300,000	36,800,000		36,000,000.0
Ending Balance		36,600,000		36,500,000	36,600,000		36,500,000
Appalachian Power Co [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		19,100,000			19,100,000			16,900,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		19,100,000			19,100,000			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
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		27,000,000.0			27,000,000.0			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			0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		37,300,000			37,300,000			19,900,000
Risk Management Assets
Risk Management Assets		37,300,000			37,300,000			19,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		700,000			700,000			600,000
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(27,200,000)			(27,200,000)			(19,200,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	(31,800,000)			(31,800,000)			(18,800,000)
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	37,100,000			37,100,000			20,100,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	1,400,000			1,400,000			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			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0			0
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	27,000,000.0			27,000,000.0			19,400,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	32,500,000			32,500,000			19,500,000
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	37,300,000			37,300,000			19,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	700,000			700,000			600,000
Appalachian Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		300,000			300,000			1,000,000.0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		700,000			700,000			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]	16.26			16.26			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]	55.49			55.49			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]	32.70			32.70			25.08
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		37,000,000.0			37,000,000.0			18,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			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]	(0.22)			(0.22)			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]	9.04			9.04			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]	1.05			1.05			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		7,600,000			7,600,000			9,000,000.0
Total Assets		(10,600,000)			(10,600,000)			(4,900,000)
Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		3,612,400,000			3,612,400,000			3,306,700,000
Total Assets		3,620,100,000			3,620,100,000			3,310,400,000
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		700,000		2,100,000	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]	400,000		2,800,000	400,000		2,300,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0	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	0		0
Settlements		(1,200,000)		(4,100,000)	(2,600,000)		(8,100,000)
Transfers into Level 3	[4],[5]	0			0		0
Transfers out of Level 3	[5]	0		0	0		400,000
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	7,400,000		3,700,000	7,400,000		4,100,000
Ending Balance		7,300,000		4,500,000	7,300,000		4,500,000
Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		2,302,800,000			2,302,800,000			2,071,500,000
Total Assets		2,302,800,000			2,302,800,000			2,071,500,000
Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,302,000,000.0			1,302,000,000.0			1,226,200,000
Total Assets		1,319,000,000.0			1,319,000,000.0			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			0
Total Assets		8,900,000			8,900,000			2,500,000
Risk Management Assets
Risk Management Assets		8,900,000			8,900,000			2,500,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		1,600,000			1,600,000			400,000
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(18,200,000)			(18,200,000)			(13,900,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	(22,400,000)			(22,400,000)			(12,200,000)
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	7,700,000			7,700,000			3,700,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	1,100,000			1,100,000			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			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0			0
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	17,000,000.0			17,000,000.0			15,100,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	21,900,000			21,900,000			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]	8,900,000			8,900,000			2,500,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	1,600,000			1,600,000			400,000
Indiana Michigan Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		100,000			100,000			600,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		400,000			400,000			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]	16.26			16.26			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]	55.49			55.49			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]	32.70			32.70			25.08
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		8,800,000			8,800,000			1,900,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		1,200,000			1,200,000			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]	(1.03)			(1.03)			(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]	5.56			5.56			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]	0.55			0.55			0.33
Ohio Power Co [Member]
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		(104,000,000.0)		(120,900,000)	(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]	1,700,000		0	100,000		(900,000)
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0	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	0		0
Settlements		600,000		2,600,000	4,900,000		5,100,000
Transfers into Level 3	[4],[5]	0			0		0
Transfers out of Level 3	[5]	0		0	0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	(3,700,000)		900,000	(100,000)		(18,000,000.0)
Ending Balance		(105,400,000)		(117,400,000)	(105,400,000)		(117,400,000)
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(700,000)			(700,000)			(300,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	100,000			100,000			0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	105,500,000			105,500,000			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			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0			0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	700,000			700,000			300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0			0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	105,400,000			105,400,000			110,300,000
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		0			0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		105,400,000			105,400,000			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]	10.58			10.58			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]	49.85			49.85			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]	27.10			27.10			28.30
Public Service Co Of Oklahoma [Member]
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		5,500,000		6,300,000	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]	4,800,000		3,900,000	16,100,000		11,900,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0	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	0		0
Settlements		(10,300,000)		(10,200,000)	(26,400,000)		(27,600,000)
Transfers into Level 3	[4],[5]	0			0		0
Transfers out of Level 3	[5]	0		0	0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	22,900,000		23,800,000	22,900,000		23,700,000
Ending Balance		22,900,000		23,800,000	22,900,000		23,800,000
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(500,000)			(500,000)			(200,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	(100,000)			(100,000)
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	23,000,000.0			23,000,000.0			10,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	100,000			100,000
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	0			0			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[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]	400,000			400,000			200,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	23,100,000			23,100,000			10,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	200,000			200,000
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		23,100,000			23,100,000			10,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		200,000			200,000			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]	(10.36)			(10.36)			(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]	0.62			0.62			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]	(2.03)			(2.03)			(1.93)
Southwestern Electric Power Co [Member]
Changes in the Fair Value of Net Trading Derivatives and other investments
Beginning Balance		500,000		(2,500,000)	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]	3,100,000		800,000	9,500,000		2,800,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0	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	0		0
Settlements		(4,500,000)		(2,400,000)	(12,000,000.0)		(7,600,000)
Transfers into Level 3	[4],[5]	0			0		0
Transfers out of Level 3	[5]	0		0	0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	15,500,000		7,400,000	15,500,000		6,700,000
Ending Balance		14,600,000		$ 3,300,000	14,600,000		$ 3,300,000
Southwestern Electric Power Co [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		15,000,000.0			15,000,000.0			3,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		400,000			400,000			1,700,000
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	(1,000,000.0)			(1,000,000.0)			(200,000)
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	(400,000)			(400,000)			0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	14,600,000			14,600,000			3,200,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0			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			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0			0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	600,000			600,000			100,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	0			0			0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	[7],[15]	15,000,000.0			15,000,000.0			3,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities	[7],[15]	400,000			400,000			1,700,000
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		3,100,000			3,100,000			0
Liabilities, Fair Value Disclosure
Risk Management Liabilities		0			0			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]	2.70			2.70			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]	3.82			3.82			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]	3.15			3.15			2.41
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets		11,900,000			11,900,000			3,300,000
Liabilities, Fair Value Disclosure
Risk Management Liabilities		400,000			400,000			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]	(10.36)			(10.36)			(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]	0.62			0.62			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]	(2.03)			(2.03)			(1.93)
Cash [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	21,100,000			21,100,000			10,500,000
Cash [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16],[17]	80,200,000			80,200,000			68,300,000
Cash [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	59,100,000			59,100,000			57,800,000
Cash [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	0			0			0
Cash [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[16]	0			0			0
Fixed Income Funds [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0			0
Fixed Income Funds [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,302,000,000.0			1,302,000,000.0			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			0
Fixed Income Funds [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,302,000,000.0			1,302,000,000.0			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			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			0
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,302,000,000.0			1,302,000,000.0			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			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		1,302,000,000.0			1,302,000,000.0			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			0
Mutual Funds Fixed Income [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0			0
Mutual Funds Fixed Income [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[18]	131,100,000			131,100,000			123,500,000
Mutual Funds Fixed Income [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		131,100,000			131,100,000			123,500,000
Mutual Funds Fixed Income [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0			0
Mutual Funds Fixed Income [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments		0			0			0
Mutual Funds Equity [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	0			0			0
Mutual Funds Equity [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	57,400,000			57,400,000			54,600,000
Mutual Funds Equity [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	57,400,000			57,400,000			54,600,000
Mutual Funds Equity [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	0			0			0
Mutual Funds Equity [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Short-term Investments	[19]	0			0			0
Cash and Cash Equivalents [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	7,600,000			7,600,000			9,000,000.0
Cash and Cash Equivalents [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	35,600,000			35,600,000			25,800,000
Cash and Cash Equivalents [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	28,000,000.0			28,000,000.0			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			0
Cash and Cash Equivalents [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	0			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]	7,600,000			7,600,000			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]	35,600,000			35,600,000			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]	28,000,000.0			28,000,000.0			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			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			0
US Government Agencies Debt Securities [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0			0
US Government Agencies Debt Securities [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,155,800,000			1,155,800,000			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			0
US Government Agencies Debt Securities [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,155,800,000			1,155,800,000			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			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			0
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,155,800,000			1,155,800,000			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			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		1,155,800,000			1,155,800,000			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			0
Corporate Debt [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0			0
Corporate Debt [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		87,300,000			87,300,000			86,300,000
Corporate Debt [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0			0
Corporate Debt [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		87,300,000			87,300,000			86,300,000
Corporate Debt [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			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			0
Corporate Debt [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		87,300,000			87,300,000			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			0
Corporate Debt [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		87,300,000			87,300,000			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			0
State and Local Jurisdiction [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0			0			0
State and Local Jurisdiction [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		58,900,000			58,900,000			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			0
State and Local Jurisdiction [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		58,900,000			58,900,000			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			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			0
State and Local Jurisdiction [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		58,900,000			58,900,000			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			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		58,900,000			58,900,000			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			0
Domestic [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			0			0
Domestic [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,274,800,000			2,274,800,000			2,054,700,000
Domestic [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,274,800,000			2,274,800,000			2,054,700,000
Domestic [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			0			0
Domestic [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0			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			0
Domestic [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,274,800,000			2,274,800,000			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]	2,274,800,000			2,274,800,000			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			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			$ 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 June 30, 2021 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows: Level 1 matures $2 million in periods 2022-2024; Level 2 matures $11 million in 2021, $37 million in periods 2022-2024, $22 million in periods 2025-2026 and $13 million in periods 2027-2033; Level 3 matures $96 million in 2021, $12 million in periods 2022-2024, $4 million in periods 2025-2026 and $(27) 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.