Fair Value Financial Assets Liabilities (Details) - USD ($)		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Assets, Fair Value Disclosure
Other Temporary Investments		$ 246,400,000		$ 388,500,000
Risk Management Assets
Derivative Assets		336,900,000		439,400,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		3,306,700,000		2,975,700,000
Total Assets		3,921,800,000		3,803,600,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		311,600,000		376,100,000
Changes in the Fair Value of Net Trading Derivatives and Other Investments
Beginning Balance		109,900,000		131,200,000		$ 40,300,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets)	[1],[2]	39,500,000		15,800,000		148,900,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	35,300,000		(100,000)		9,800,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)	[3]	13,800,000		(15,100,000)		15,700,000
Settlements		(113,100,000)		(117,600,000)		(214,000,000.0)
Transfers into Level 3	[4],[5]	(3,800,000)		(600,000)		15,800,000
Transfers out of Level 3	[5]	5,600,000		35,600,000		(1,600,000)
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	26,100,000		60,700,000		116,300,000
Ending Balance		113,300,000		109,900,000		131,200,000
Other [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		10,500,000		17,100,000
Risk Management Assets
Derivative Assets		(218,500,000)		(411,200,000)
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		9,000,000.0		8,600,000
Total Assets		(199,000,000.0)		(385,500,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities		(221,900,000)		(445,500,000)
Level 1 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		235,900,000		371,400,000
Risk Management Assets
Derivative Assets		900,000		4,000,000.0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		2,071,500,000		1,774,600,000
Total Assets		2,308,300,000		2,150,000,000.0
Liabilities, Fair Value Disclosure
Derivative Liabilities		900,000		3,800,000
Level 2 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		0		0
Risk Management Assets
Derivative Assets		298,200,000		474,200,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,226,200,000		1,192,500,000
Total Assets		1,524,400,000		1,666,700,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		357,800,000		555,300,000
Level 3 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		0		0
Risk Management Assets
Derivative Assets		256,300,000		372,400,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
Total Assets		288,100,000		372,400,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		174,800,000		262,500,000
2020 [Member] | Level 2 [Member]
Fair Value Measurements 1 (Textuals)
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities				(7,000,000)
2020 [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
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		47,000,000
2021 - 2023 [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 - 2023 [Member] | Level 3 [Member]
Fair Value Measurements 1 (Textuals)
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities				36,000,000
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		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		37,000,000
2024 - 2025 [Member] | Level 3 [Member]
Fair Value Measurements 1 (Textuals)
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities				25,000,000
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		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		14,000,000
2026 - 2032 [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)
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		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		(13,000,000)
Risk Management Commodity Contracts [Member]
Risk Management Assets
Derivative Assets	[7]	322,100,000	[8]	408,800,000	[9]
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	218,900,000	[8]	239,000,000.0	[9]
Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7]	(190,000,000.0)	[8]	(404,500,000)	[9]
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	(193,400,000)	[8]	(438,800,000)	[9]
Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7]	900,000	[8]	4,000,000.0	[9]
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	900,000	[8]	3,800,000	[9]
Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7]	258,800,000	[8]	440,100,000	[9]
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	244,200,000	[8]	450,000,000.0	[9]
Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7]	252,400,000	[8]	369,200,000	[9]
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	167,200,000	[8]	224,000,000.0	[9]
Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		213,500,000		296,700,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		169,700,000		249,300,000
Energy Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	5.33		(0.05)
Energy Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	100.47		177.30
Energy Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	32.73		31.31
Natural Gas Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		1,700,000		4,900,000
Natural Gas Contracts [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[12]	2.18		1.89
Natural Gas Contracts [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[12]	2.77		2.51
Natural Gas Contracts [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[11],[12]	2.40		2.19
FTRs [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		42,800,000		75,700,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		3,400,000		8,300,000
FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	(15.08)		(8.52)
FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	9.66		9.34
FTRs [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10],[11]	0.19		0.42
Commodity Hedges [Member]
Risk Management Assets
Derivative Assets	[7]	9,800,000		11,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	85,200,000		137,100,000
Commodity Hedges [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7]	(28,500,000)		(6,700,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	(28,500,000)		(6,700,000)
Commodity Hedges [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7]	0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	0		0
Commodity Hedges [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7]	34,400,000		15,000,000.0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	106,100,000		105,300,000
Commodity Hedges [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7]	3,900,000		3,200,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7]	7,600,000		38,500,000
Interest Rate Foreign Currency Hedges [Member]
Risk Management Assets
Derivative Assets		2,400,000		4,600,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		3,400,000
Interest Rate Foreign Currency Hedges [Member] | Other [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Interest Rate Foreign Currency Hedges [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Interest Rate Foreign Currency Hedges [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets		2,400,000		4,600,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		3,400,000
Interest Rate Foreign Currency Hedges [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Fair Value Hedges [Member]
Risk Management Assets
Derivative Assets		2,600,000		14,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		4,100,000
Fair Value Hedges [Member] | Other [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Fair Value Hedges [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Fair Value Hedges [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets		2,600,000		14,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		4,100,000
Fair Value Hedges [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Other Investments [Member]
Risk Management Assets
Derivative Assets	[13]	31,800,000
Other Investments [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[13]	0
Other Investments [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[13]	0
Other Investments [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[13]	0
Other Investments [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[13]	31,800,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Other Investments [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[14]	0.10
Other Investments [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[14]	0.20
Other Investments [Member] | Level 3 [Member] | Weighted Average [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[14]	0.15
AEP Texas Inc. [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		28,700,000		154,700,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		28,700,000
AEP Texas Inc. [Member] | Other [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0		0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		(400,000)
AEP Texas Inc. [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		28,700,000		154,700,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		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		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
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Derivative Assets	[7]	0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7]	(400,000)
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7]	0
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7]	400,000
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7]	0
Appalachian Power Co [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		16,900,000		23,500,000
Risk Management Assets
Derivative Assets		22,500,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		39,400,000		63,000,000.0
Liabilities, Fair Value Disclosure
Derivative Liabilities		4,700,000
Changes in the Fair Value of Net Trading Derivatives and Other Investments
Beginning Balance		37,700,000		57,800,000		24,700,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets)	[1],[2]	13,200,000		(13,900,000)		104,100,000
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
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
Settlements		(51,600,000)		(42,500,000)		(127,900,000)
Transfers into Level 3	[4],[5]	0		(500,000)		0
Transfers out of Level 3	[5]	700,000		(700,000)		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	19,300,000		37,500,000		56,900,000
Ending Balance		19,300,000		37,700,000		57,800,000
Appalachian Power Co [Member] | Other [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0		0
Risk Management Assets
Derivative Assets		(19,200,000)
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		(19,200,000)		(85,600,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities		(18,800,000)
Appalachian Power Co [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		16,900,000		23,500,000
Risk Management Assets
Derivative Assets		0
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		16,900,000		23,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Appalachian Power Co [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0		0
Risk Management Assets
Derivative Assets		21,800,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		21,800,000		84,600,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		22,900,000
Appalachian Power Co [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Cash and Cash Equivalents		0		0
Risk Management Assets
Derivative Assets		19,900,000		40,500,000
Spent Nuclear Fuel and Decommissioning Trusts
Total Assets		19,900,000		40,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		600,000		2,800,000
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Derivative Assets	[7],[15]	20,100,000		39,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	1,300,000		1,900,000
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7],[15]	(19,200,000)		(85,600,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	(18,800,000)		(84,900,000)
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		0
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	19,400,000		84,600,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	19,500,000		84,000,000.0
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	19,900,000		40,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	600,000		2,800,000
Appalachian Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		1,000,000.0		5,700,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		600,000		2,600,000
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]	10.84		12.70
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]	41.09		41.20
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]	25.08		25.92
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		18,900,000		34,800,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		0		200,000
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	0.04		(0.14)
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | High [Member]
Level 3 Quantitative Information
Fair Value Significant Unobservable Input Price Per Unit	[10]	5.61		7.08
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]	1.13		1.70
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges [Member]
Risk Management Assets
Derivative Assets		2,400,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		3,400,000
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges [Member] | Other [Member]
Risk Management Assets
Derivative Assets		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets		2,400,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		3,400,000
Appalachian Power Co [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		0
Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		3,306,700,000		2,975,700,000
Total Assets		3,310,400,000		2,985,600,000
Changes in the Fair Value of Net Trading Derivatives and Other Investments
Beginning Balance		5,800,000		8,900,000		7,600,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets)	[1],[2]	2,500,000		4,700,000		14,200,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	[1]	0		0		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
Settlements		(8,600,000)		(13,000,000.0)		(21,300,000)
Transfers into Level 3	[4],[5]	0		(300,000)		0
Transfers out of Level 3	[5]	400,000		(400,000)		(300,000)
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	2,000,000.0		5,900,000		8,700,000
Ending Balance		2,100,000		5,800,000		8,900,000
Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		9,000,000.0		8,600,000
Total Assets		(4,900,000)		(49,000,000.0)
Indiana Michigan Power Co [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		2,071,500,000		1,774,600,000
Total Assets		2,071,500,000		1,774,600,000
Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,226,200,000		1,192,500,000
Total Assets		1,241,300,000		1,252,000,000.0
Indiana Michigan Power Co [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		2,500,000		8,000,000.0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
Total Assets		2,500,000		8,000,000.0
Liabilities, Fair Value Disclosure
Derivative Liabilities		400,000		2,200,000
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Derivative Assets	[7],[15]	3,700,000		9,900,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	200,000		500,000
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7],[15]	(13,900,000)		(57,600,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	(12,200,000)		(55,100,000)
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		0
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	15,100,000		59,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	12,000,000.0		53,400,000
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	2,500,000		8,000,000.0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	400,000		2,200,000
Indiana Michigan Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		600,000		3,400,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		300,000		1,500,000
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]	10.84		12.70
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]	41.09		41.20
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]	25.08		25.92
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		1,900,000		4,600,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		100,000		700,000
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]	(1.96)		(0.75)
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]	3.69		4.07
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		0.74
Ohio Power Co [Member]
Changes in the Fair Value of Net Trading Derivatives and Other Investments
Beginning Balance		(103,600,000)		(99,400,000)		(132,400,000)
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets)	[1],[2]	(1,600,000)		(900,000)		1,800,000
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
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
Settlements		8,900,000		6,600,000		4,600,000
Transfers into Level 3	[4],[5]	0		0		0
Transfers out of Level 3	[5]	0		0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	(14,000,000.0)		(9,900,000)		26,600,000
Ending Balance		(110,300,000)		(103,600,000)		(99,400,000)
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Derivative Assets	[7],[15]	0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	110,300,000		103,600,000
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7],[15]	(300,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	300,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		0
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	110,300,000		103,600,000
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		110,300,000		103,600,000
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]	16.19		29.23
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]	46.98		61.43
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]	28.30		42.46
Public Service Co Of Oklahoma [Member]
Changes in the Fair Value of Net Trading Derivatives and Other Investments
Beginning Balance		15,800,000		9,500,000		6,200,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets)	[1],[2]	11,900,000		13,500,000		18,100,000
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
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
Settlements		(27,600,000)		(23,000,000.0)		(24,300,000)
Transfers into Level 3	[4],[5]	0		0		0
Transfers out of Level 3	[5]	0		0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	10,200,000		15,800,000		9,500,000
Ending Balance		10,300,000		15,800,000		9,500,000
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Derivative Assets	[7],[15]	10,300,000		15,800,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]			0
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7],[15]	(200,000)		(500,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]			(500,000)
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]			0
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	200,000		0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]			0
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	10,300,000		16,300,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]			500,000
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		10,300,000		16,300,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		0		500,000
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]	(6.93)		(8.52)
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]	0.48		0.85
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]	(1.93)		(2.31)
Southwestern Electric Power Co [Member]
Changes in the Fair Value of Net Trading Derivatives and Other Investments
Beginning Balance		1,400,000		2,300,000		5,900,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets)	[1],[2]	2,800,000		6,000,000.0		(4,800,000)
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
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
Settlements		(6,600,000)		(9,600,000)		(2,100,000)
Transfers into Level 3	[4],[5]	0		0		0
Transfers out of Level 3	[5]	0		0		0
Changes in Fair Value Allocated to Regulated Jurisdiction	[6]	4,000,000.0		2,700,000		3,300,000
Ending Balance		1,600,000		1,400,000		$ 2,300,000
Southwestern Electric Power Co [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		3,300,000		6,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		1,700,000		5,100,000
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member]
Risk Management Assets
Derivative Assets	[7],[15]	3,200,000		6,400,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	1,700,000		5,000,000.0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]
Risk Management Assets
Derivative Assets	[7],[15]	(200,000)		(100,000)
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		(100,000)
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	100,000		0
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	0		0
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets	[7],[15]	3,300,000		6,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities	[7],[15]	1,700,000		5,100,000
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		0		0
Liabilities, Fair Value Disclosure
Derivative Liabilities		1,700,000		4,900,000
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]	2.18		1.89
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]	2.77		2.51
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]	2.41		2.18
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member]
Risk Management Assets
Derivative Assets		3,300,000		6,500,000
Liabilities, Fair Value Disclosure
Derivative Liabilities		0		200,000
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]	(6.93)		(8.52)
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]	0.48		0.85
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]	(1.93)		(2.31)
Cash [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[16],[17]	68,300,000		214,700,000
Cash [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[16]	10,500,000		17,100,000
Cash [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[16]	57,800,000		197,600,000
Cash [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[16]	0		0
Cash [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[16]	0		0
Mutual Funds Fixed Income [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[18]	123,500,000		123,300,000
Mutual Funds Fixed Income [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		0		0
Mutual Funds Fixed Income [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		123,500,000		123,300,000
Mutual Funds Fixed Income [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		0		0
Mutual Funds Fixed Income [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments		0		0
Mutual Funds Equity [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[19]	54,600,000		50,500,000
Mutual Funds Equity [Member] | Other [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[19]	0		0
Mutual Funds Equity [Member] | Level 1 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[19]	54,600,000		50,500,000
Mutual Funds Equity [Member] | Level 2 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[19]	0		0
Mutual Funds Equity [Member] | Level 3 [Member]
Assets, Fair Value Disclosure
Other Temporary Investments	[19]	0		0
Cash and Cash Equivalents [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	25,800,000		15,300,000
Cash and Cash Equivalents [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	9,000,000.0		8,600,000
Cash and Cash Equivalents [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	16,800,000		6,700,000
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]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[20]	25,800,000		15,300,000
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]	9,000,000.0		8,600,000
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]	16,800,000		6,700,000
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]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,025,600,000		1,112,500,000
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] | 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		1,025,600,000		1,112,500,000
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]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,025,600,000		1,112,500,000
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] | 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		1,025,600,000		1,112,500,000
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 Securities [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		86,300,000		72,400,000
Corporate Debt Securities [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
Corporate Debt Securities [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
Corporate Debt Securities [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		86,300,000		72,400,000
Corporate Debt Securities [Member] | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		86,300,000		72,400,000
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
Corporate 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
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		86,300,000		72,400,000
Corporate 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
State and Local Jurisdiction
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		114,300,000		7,600,000
State and Local Jurisdiction | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
State and Local Jurisdiction | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
State and Local Jurisdiction | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		114,300,000		7,600,000
State and Local Jurisdiction | Level 3 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
State and Local Jurisdiction | Indiana Michigan Power Co [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		114,300,000		7,600,000
State and Local Jurisdiction | 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 | 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 | Indiana Michigan Power Co [Member] | Level 2 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		114,300,000		7,600,000
State and Local Jurisdiction | Indiana Michigan Power Co [Member] | Level 3 [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		1,226,200,000		1,192,500,000
Fixed Income Funds [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		0		0
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		1,226,200,000		1,192,500,000
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]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts		1,226,200,000		1,192,500,000
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] | 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		1,226,200,000		1,192,500,000
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
Domestic [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,054,700,000		1,767,900,000
Domestic [Member] | Other [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	0		0
Domestic [Member] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,054,700,000		1,767,900,000
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]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,054,700,000		1,767,900,000
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] | Level 1 [Member]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	[19]	2,054,700,000		1,767,900,000
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 December 31, 2020 maturities 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.

[9] The December 31, 2019 maturities of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows: Level 2 matures $(7) million in 2020 and $(3) million in periods 2021-2023; Level 3 matures $96 million in 2020, $36 million in periods 2021-2023, $25 million in periods 2024-2025 and $(12) million in periods 2026-2032.  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 10 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.