Financing Activities (Details) - USD ($)		1 Months Ended	3 Months Ended								9 Months Ended
		Oct. 28, 2021	Sep. 30, 2021		Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020		Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021		Sep. 30, 2020	Dec. 31, 2020
Long-term Debt
Senior Unsecured Notes			$ 28,778,100,000								$ 28,778,100,000			$ 25,116,100,000
Pollution Control Bonds			1,881,000,000								1,881,000,000			1,936,700,000
Notes Payable			235,100,000								235,100,000			239,100,000
Securitization Bonds			639,700,000								639,700,000			716,400,000
Spent Nuclear Fuel Obligation	[1]		281,300,000								281,300,000			281,200,000
Junior Subordinated Notes	[2]		1,629,900,000								1,629,900,000			1,624,100,000
Other Long-term Debt			1,133,200,000								1,133,200,000			1,158,900,000
Total Long-term Debt Outstanding			34,578,300,000								34,578,300,000			31,072,500,000
Long-term Debt Due Within One Year			2,521,800,000								2,521,800,000			2,086,100,000
Long-term Debt			32,056,500,000								32,056,500,000			28,986,400,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										5,115,800,000
Repayments of Long-term Debt											1,549,800,000		$ 700,500,000
Short-term Debt:
Securitized Debt for Receivables	[4]		750,000,000.0								750,000,000.0			592,000,000.0
Commercial Paper			1,254,000,000								1,254,000,000			1,852,300,000
364-Day Term Loan			500,000,000.0								500,000,000.0			0
Notes Payable			0								0			35,000,000.0
Total Short-term Debt			$ 2,504,000,000								$ 2,504,000,000			$ 2,479,300,000
Securitized Debt for Receivables	[4],[5]		0.19%								0.19%			0.85%
Comparative Accounts Receivable Information
Effective Interest Rates on Securitization of Accounts Receivable			0.18%				0.36%				0.19%		1.05%
Net Uncollectible Accounts Receivable Written Off			$ 7,500,000				$ 2,900,000				$ 22,600,000		$ 10,500,000
Customer Accounts Receivable Managed Portfolio
Accounts Receivable Retained Interest and Pledged as Collateral Less Uncollectible Accounts			1,031,300,000								1,031,300,000			$ 958,400,000
Total Principal Outstanding			750,000,000.0								750,000,000.0			592,000,000.0
Delinquent Securitized Accounts Receivable			60,000,000.0								60,000,000.0			62,300,000
Bad Debt Reserves Related to Securitization, Sale of Accounts Receivable			39,800,000								39,800,000			60,000,000.0
Unbilled Receivables Related to Securitization, Sale of Accounts Receivable			224,500,000								224,500,000			296,800,000
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			4,623,000,000				4,066,400,000				12,730,600,000		11,307,900,000
Financing Activities (Textuals)
Maximum Value of Shares to be Issued Under ATM Program											$ 1,000,000,000
Maximum Percentage Paid to Selling Agents											2.00%
Issuance of Common Stock											$ 548,000,000.0		136,500,000
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition			327,000,000								$ 327,000,000			$ 324,000,000
Maximum Percentage Debt to Capitalization											67.50%
Total Commitment from Bank Conduits to Finance Receivables			750,000,000								$ 750,000,000
Forward Equity Purchase Contract Included in Current and Noncurrent Liabilities as of September 30,			(7,800,000)		$ (10,500,000)	$ 19,100,000	103,700,000		$ 1,600,000	$ 30,200,000
Commitment from Bank Conduits to Finance Receivables			125,000,000								125,000,000
Commitment from Bank Conduits to Finance Receivables Two			625,000,000								$ 625,000,000
Equity Distribution Agreement
Financing Activities (Textuals)
Stock Issued During Period, Shares, New Issues											5,421,825
Issuance of Common Stock											$ 461,000,000
2020 Equity Units [Member]
Financing Activities (Textuals)
Equity Units Issued											17,000,000
Per Unit Conversion for Equity Units			$ 50								$ 50
Net Equity Units Issuance Proceeds											$ 833,000,000
Corporate unit ownership share of an equity unit			5.00%								5.00%
Principal Amounts of Junior Subordinated Debt											$ 1,000
Forward Equity Purchase Contract Date											2023
Equity Units Annual Distribution Rate			6.125%								6.125%
Forward Equity Contract Payment Rate			4.825%								4.825%
Maximum Shares Issued Under Equity Units Conversion											10,205,100
2019 Equity Units [Member]
Financing Activities (Textuals)
Equity Units Issued											16,100,000
Per Unit Conversion for Equity Units			$ 50								$ 50
Net Equity Units Issuance Proceeds											$ 785,000,000
Corporate unit ownership share of an equity unit			5.00%								5.00%
Principal Amounts of Junior Subordinated Debt											$ 1,000
Forward Equity Purchase Contract Date											2022
Equity Units Annual Distribution Rate			6.125%								6.125%
Forward Equity Contract Payment Rate			2.725%								2.725%
Maximum Shares Issued Under Equity Units Conversion											9,701,860
Junior Subordinated Debt [Member] | 2020 Equity Units [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt											$ 850,000,000
Interest Rate (Percentage)			1.30%								1.30%
Junior Subordinated Debt [Member] | 2019 Equity Units [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt											$ 805,000,000
Interest Rate (Percentage)			3.40%								3.40%
Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 175,000,000.0
Due Date											2028
Interest Rate (Percentage)			1.80%								1.80%
Commercial Paper [Member]
Short-term Debt:
Weighted Average Interest Rate	[5]		0.25%								0.25%			0.29%
364 Day Term Loan
Short-term Debt:
Weighted Average Interest Rate	[5]		0.72%								0.72%			0.00%
Loans Payable [Member]
Short-term Debt:
Weighted Average Interest Rate	[5]		0.00%								0.00%			2.55%
AEP Texas Inc. [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 5,216,100,000								$ 5,216,100,000			$ 4,820,400,000
Long-term Debt Due Within One Year			315,100,000								315,100,000			88,700,000
Long-term Debt			4,901,000,000								4,901,000,000			4,731,700,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 52,200,000		$ 356,500,000
Financing Activities (Textuals)
Maximum Percentage Debt to Capitalization											67.50%
AEP Texas Inc. [Member] | Utility [Member]
Maximum Interest Rate											0.40%		2.70%
Minimum Interest Rate											0.02%		0.33%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 355,500,000
Maximum Loans to Money Pool											104,700,000
Average Borrowings from Money Pool											234,700,000
Average Loans to Money Pool											45,200,000
Net Loans (Borrowings) to/from Money Pool			47,600,000								47,600,000
Authorized Short Term Borrowing Limit											$ 500,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.33%		1.55%
Average Interest Rate For Funds Loaned											0.27%		0.87%
AEP Texas Inc. [Member] | Nonutility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Loans to Money Pool											$ 7,100,000
Average Loans to Money Pool											6,900,000
Net Loans (Borrowings) to/from Money Pool			$ 7,000,000.0								$ 7,000,000.0
Maximum and Minimum Interest Rates
Maximum Interest Rate For Funds Loaned											0.41%		2.70%
Minimum Interest Rate for Funds Loaned											0.21%		0.33%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Loaned											0.34%		1.44%
AEP Texas Inc. [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 29,700,000
Due Date											2024
Interest Rate (Percentage)			2.85%								2.85%
AEP Texas Inc. [Member] | Securitization Bonds Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 22,500,000
Due Date											2025
Interest Rate (Percentage)			2.06%								2.06%
AEP Texas Inc. [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 450,000,000.0
Due Date											2051
Interest Rate (Percentage)			3.45%								3.45%
AEP Transmission Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 4,393,400,000								$ 4,393,400,000			3,948,500,000
Long-term Debt Due Within One Year			50,000,000.0								50,000,000.0			50,000,000.0
Long-term Debt			4,343,400,000								4,343,400,000			3,898,500,000
Financing Activities (Textuals)
Sub-Limit of Secured Debt			$ 50,000,000								$ 50,000,000
Maximum Percentage of Consolidated Tangible Net Assets			10.00%								10.00%
Tangible Capital to Tangible Assets			0.10%								0.10%
Maximum Percentage Debt to Capitalization											67.50%
AEP Transmission Co [Member] | Utility [Member]
Maximum Interest Rate											0.40%		2.70%
Minimum Interest Rate											0.02%		0.33%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 444,900,000
Maximum Loans to Money Pool											117,300,000
Average Borrowings from Money Pool											225,100,000
Average Loans to Money Pool											24,400,000
Net Loans (Borrowings) to/from Money Pool			$ 73,900,000								73,900,000
Authorized Short Term Borrowing Limit	[6]										$ 820,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.32%		1.63%
Average Interest Rate For Funds Loaned											0.07%		2.00%
AEP Transmission Co [Member] | Direct Borrowing [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 14,600,000
Maximum Loans to Money Pool											224,200,000
Average Borrowings from Money Pool											1,600,000
Average Loans to Money Pool											139,300,000
Borrowings from Parent			8,600,000								8,600,000
Loans to Parent			$ 0								0
Authorized Short Term Borrowing Limit	[7]										$ 50,000,000.0
Maximum and Minimum Interest Rates
Maximum Interest Rate for Funds Borrowed											0.86%		2.70%
Minimum Interest Rate For Funds Borrowed											0.25%		0.50%
Maximum Interest Rate For Funds Loaned											0.86%		2.70%
Minimum Interest Rate for Funds Loaned											0.25%		0.50%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.35%		1.45%
Average Interest Rate For Funds Loaned											0.34%		1.40%
AEP Transmission Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 450,000,000.0
Due Date											2051
Interest Rate (Percentage)			2.75%								2.75%
Appalachian Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 4,937,800,000								$ 4,937,800,000			4,834,100,000
Long-term Debt Due Within One Year			380,600,000								380,600,000			518,300,000
Long-term Debt			4,557,200,000								4,557,200,000			4,315,800,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											393,000,000.0		$ 90,300,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			131,000,000.0								131,000,000.0			136,000,000.0
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			342,200,000				323,500,000				$ 980,600,000		961,800,000
Financing Activities (Textuals)
Maximum Percentage Debt to Capitalization											67.50%
Appalachian Power Co [Member] | Servicing Contracts [Member]
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			1,300,000	[8]			2,000,000.0				$ 3,700,000	[8]	$ 5,000,000.0
Appalachian Power Co [Member] | Utility [Member]
Maximum Interest Rate											0.40%		2.70%
Minimum Interest Rate											0.02%		0.33%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 27,800,000
Maximum Loans to Money Pool											616,900,000
Average Borrowings from Money Pool											13,200,000
Average Loans to Money Pool											134,400,000
Net Loans (Borrowings) to/from Money Pool			$ 185,200,000								185,200,000
Authorized Short Term Borrowing Limit											$ 500,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.28%		2.14%
Average Interest Rate For Funds Loaned											0.28%		0.99%
Appalachian Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 100,000
Due Date											2026
Interest Rate (Percentage)			13.72%								13.72%
Appalachian Power Co [Member] | Pollution Control Bond [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 17,500,000
Due Date											2021
Interest Rate (Percentage)			4.63%								4.63%
Appalachian Power Co [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 25,400,000
Due Date											2023
Interest Rate (Percentage)			2.01%								2.01%
Appalachian Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt											$ 500,000,000.0
Due Date											2031
Interest Rate (Percentage)			2.70%								2.70%
Appalachian Power Co [Member] | Senior Unsecured Notes Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 350,000,000.0
Due Date											2021
Interest Rate (Percentage)			4.60%								4.60%
Indiana Michigan Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 3,231,100,000								$ 3,231,100,000			3,029,900,000
Long-term Debt Due Within One Year			132,700,000								132,700,000			369,600,000
Long-term Debt			3,098,400,000								3,098,400,000			2,660,300,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											307,200,000		$ 71,100,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			173,900,000								173,900,000			170,500,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			536,800,000				532,300,000				1,478,900,000		1,443,600,000
Financing Activities (Textuals)
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition			327,000,000								327,000,000			324,000,000
Reacquired Pollution Control Bonds Held by Trustees			40,000,000								$ 40,000,000
Maximum Percentage Debt to Capitalization											67.50%
Indiana Michigan Power Co [Member] | Servicing Contracts [Member]
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			2,100,000	[8]			3,900,000				$ 5,300,000	[8]	$ 9,300,000
Indiana Michigan Power Co [Member] | Utility [Member]
Maximum Interest Rate											0.40%		2.70%
Minimum Interest Rate											0.02%		0.33%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 166,500,000
Maximum Loans to Money Pool											368,200,000
Average Borrowings from Money Pool											117,500,000
Average Loans to Money Pool											76,300,000
Net Loans (Borrowings) to/from Money Pool			$ 80,600,000								80,600,000
Authorized Short Term Borrowing Limit											$ 500,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.32%		1.30%
Average Interest Rate For Funds Loaned											0.25%		1.44%
Indiana Michigan Power Co [Member] | Notes Payable, Other Payables [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 64,900,000
Due Date											2025
Interest Rate (Percentage)			0.93%								0.93%
Indiana Michigan Power Co [Member] | Notes Payable, Other Payables [Member] | Subsequent Event [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt		$ 8,000,000
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 1,900,000
Due Date											2021
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 4,500,000
Due Date											2022
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Four [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 5,400,000
Due Date											2022
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Five [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 14,300,000
Due Date											2023
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Six [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 12,600,000
Due Date											2024
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Seven [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 19,600,000
Due Date											2025
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Eight [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 7,400,000
Due Date											2025
Interest Rate (Percentage)			0.93%								0.93%
Indiana Michigan Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 200,000,000.0
Due Date											2021
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Other Long Term Debt Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 1,500,000
Due Date											2025
Interest Rate (Percentage)			6.00%								6.00%
Indiana Michigan Power Co [Member] | Pollution Control Bond [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 40,000,000.0
Due Date											2021
Interest Rate (Percentage)			2.05%								2.05%
Indiana Michigan Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 450,000,000.0
Due Date											2051
Interest Rate (Percentage)			3.25%								3.25%
Ohio Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 3,468,100,000								$ 3,468,100,000			2,430,200,000
Long-term Debt Due Within One Year			500,100,000								500,100,000			500,100,000
Long-term Debt			2,968,000,000								2,968,000,000			1,930,100,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											100,000		$ 100,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			377,300,000								377,300,000			398,800,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			668,400,000				666,000,000.0				1,867,500,000		1,793,000,000
Ohio Power Co [Member] | Servicing Contracts [Member]
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			4,600,000	[8]			9,800,000				$ 3,500,000	[8]	$ 19,600,000
Ohio Power Co [Member] | Utility [Member]
Maximum Interest Rate											0.40%		2.70%
Minimum Interest Rate											0.02%		0.33%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 259,200,000
Maximum Loans to Money Pool											622,900,000
Average Borrowings from Money Pool											62,800,000
Average Loans to Money Pool											182,500,000
Net Loans (Borrowings) to/from Money Pool			$ 622,900,000								622,900,000
Authorized Short Term Borrowing Limit											$ 500,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.27%		1.32%
Average Interest Rate For Funds Loaned											0.15%		2.06%
Ohio Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 100,000
Due Date											2028
Interest Rate (Percentage)			1.15%								1.15%
Ohio Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 450,000,000.0
Due Date											2031
Interest Rate (Percentage)			1.63%								1.63%
Ohio Power Co [Member] | Senior Unsecured Notes [Member] | Subsequent Event [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt		$ 500,000,000
Ohio Power Co [Member] | Senior Unsecured Notes Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 600,000,000.0
Due Date											2051
Interest Rate (Percentage)			2.90%								2.90%
Public Service Co Of Oklahoma [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 1,913,300,000								$ 1,913,300,000			1,373,800,000
Long-term Debt Due Within One Year			500,000								500,000			500,000
Long-term Debt			1,912,800,000								1,912,800,000			1,373,300,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											750,400,000		$ 13,000,000.0
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			147,100,000								147,100,000			85,000,000.0
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			460,100,000				369,200,000				$ 1,068,800,000		961,400,000
Financing Activities (Textuals)
Maximum Percentage Debt to Capitalization											67.50%
Public Service Co Of Oklahoma [Member] | Servicing Contracts [Member]
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			1,100,000	[8]			1,500,000				$ 2,400,000	[8]	$ 3,800,000
Public Service Co Of Oklahoma [Member] | Utility [Member]
Maximum Interest Rate											0.40%		2.70%
Minimum Interest Rate											0.02%		0.33%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 267,700,000
Maximum Loans to Money Pool											747,300,000
Average Borrowings from Money Pool											142,800,000
Average Loans to Money Pool											184,900,000
Net Loans (Borrowings) to/from Money Pool			$ 59,500,000								59,500,000
Authorized Short Term Borrowing Limit											$ 300,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.34%		1.24%
Average Interest Rate For Funds Loaned											0.06%		1.95%
Public Service Co Of Oklahoma [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 400,000
Due Date											2027
Interest Rate (Percentage)			3.00%								3.00%
Public Service Co Of Oklahoma [Member] | Other Long Term Debt Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 500,000,000.0
Due Date											2022
Interest Rate (Variable)											Variable
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 400,000,000.0
Due Date											2031
Interest Rate (Percentage)			2.20%								2.20%
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 400,000,000.0
Due Date											2051
Interest Rate (Percentage)			3.15%								3.15%
Public Service Co Of Oklahoma [Member] | OtherLongTermDebtThree
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 500,000,000.0
Due Date											2022
Interest Rate (Variable)											Variable
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes Three
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 250,000,000.0
Due Date											2021
Interest Rate (Percentage)			4.40%								4.40%
Southwestern Electric Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 3,129,900,000								$ 3,129,900,000			2,636,400,000
Long-term Debt Due Within One Year			381,200,000								381,200,000			106,200,000
Long-term Debt			2,748,700,000								2,748,700,000			2,530,200,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											4,700,000		$ 19,700,000
Short-term Debt:
Notes Payable			0								0			35,000,000.0
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			185,600,000								185,600,000			$ 158,600,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			488,500,000				478,300,000				$ 1,265,500,000		1,225,300,000
Financing Activities (Textuals)
Maximum Percentage Debt to Capitalization											67.50%
Southwestern Electric Power Co [Member] | Servicing Contracts [Member]
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			1,300,000	[8]			2,800,000				$ 4,100,000	[8]	$ 6,800,000
Southwestern Electric Power Co [Member] | Utility [Member]
Maximum Interest Rate											0.40%		2.70%
Minimum Interest Rate											0.02%		0.33%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 280,300,000
Maximum Loans to Money Pool											156,400,000
Average Borrowings from Money Pool											148,000,000.0
Average Loans to Money Pool											142,000,000.0
Net Loans (Borrowings) to/from Money Pool			(122,900,000)								(122,900,000)
Authorized Short Term Borrowing Limit											$ 350,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											0.28%		1.55%
Average Interest Rate For Funds Loaned											0.38%		0.00%
Southwestern Electric Power Co [Member] | Nonutility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Loans to Money Pool											$ 2,100,000
Average Loans to Money Pool											2,100,000
Net Loans (Borrowings) to/from Money Pool			$ 2,100,000								$ 2,100,000
Maximum and Minimum Interest Rates
Maximum Interest Rate For Funds Loaned											0.41%		2.70%
Minimum Interest Rate for Funds Loaned											0.21%		0.33%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Loaned											0.34%		1.44%
Southwestern Electric Power Co [Member] | Notes Payable, Other Payables [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 3,200,000
Due Date											2032
Interest Rate (Percentage)			4.58%								4.58%
Southwestern Electric Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 1,500,000
Due Date											2028
Interest Rate (Percentage)			4.68%								4.68%
Southwestern Electric Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 500,000,000.0
Due Date											2026
Interest Rate (Percentage)			1.65%								1.65%
Southwestern Electric Power Co [Member] | Loans Payable [Member]
Short-term Debt:
Weighted Average Interest Rate	[5]		0.00%								0.00%			2.55%
Transource Energy [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 25,900,000
Due Date											2023
Interest Rate (Variable)											Variable
Transource Energy [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 1,200,000
Due Date											2050
Interest Rate (Percentage)			2.75%								2.75%
Transource Energy [Member] | Senior Unsecured Notes Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 1,200,000
Due Date											2050
Interest Rate (Percentage)			2.75%								2.75%
Kentucky Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 150,000,000.0
Due Date											2023
Interest Rate (Variable)											Variable
Kentucky Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 39,800,000
Due Date											2021
Interest Rate (Percentage)			7.25%								7.25%
Maximum [Member] | 2020 Equity Units [Member]
Financing Activities (Textuals)
AEP Share Price for Equity Unit Conversion			$ 99.95								$ 99.95
Shares Per Equity Unit			0.6003								0.6003
Maximum [Member] | 2019 Equity Units [Member]
Financing Activities (Textuals)
AEP Share Price for Equity Unit Conversion			$ 99.58								$ 99.58
Shares Per Equity Unit			0.6026								0.6026
Minimum [Member] | 2020 Equity Units [Member]
Financing Activities (Textuals)
AEP Share Price for Equity Unit Conversion			$ 83.29								$ 83.29
Shares Per Equity Unit			0.5003								0.5003
Minimum [Member] | 2019 Equity Units [Member]
Financing Activities (Textuals)
AEP Share Price for Equity Unit Conversion			$ 82.98								$ 82.98
Shares Per Equity Unit			0.5021								0.5021
Retained Earnings [Member]
Financing Activities (Textuals)
Forward Equity Purchase Contract Included in Current and Noncurrent Liabilities as of September 30,					400,000	600,000					$ 0		$ 120,600,000
Additional Paid-in Capital [Member]
Financing Activities (Textuals)
Forward Equity Purchase Contract Included in Current and Noncurrent Liabilities as of September 30,			$ (6,300,000)		$ 200,000	$ 21,900,000	$ 104,000,000.0	[9]	$ 2,600,000	$ 29,000,000.0
Additional Paid-in Capital [Member] | 2020 Equity Units [Member]
Financing Activities (Textuals)
Forward Equity Purchase Contract Included in Current and Noncurrent Liabilities as of September 30,											121,000,000
Additional Paid-in Capital [Member] | 2019 Equity Units [Member]
Financing Activities (Textuals)
Forward Equity Purchase Contract Included in Current and Noncurrent Liabilities as of September 30,											$ 62,000,000

[1] Pursuant to the Nuclear Waste Policy Act of 1982, I&M, a nuclear licensee, has an obligation to the United States Department of Energy for SNF disposal. The obligation includes a one-time fee for nuclear fuel consumed prior to April 7, 1983. Trust fund assets related to this obligation were $327 million and $324 million as of September 30, 2021 and December 31, 2020, respectively, and are included in Spent Nuclear Fuel and Decommissioning Trusts on the balance sheets.

[2] See “Equity Units” section below for additional information.

[3] Amounts indicated on the statements of cash flows are net of issuance costs and premium or discount and will not tie to the issuance amounts.

[4] Amount of securitized debt for receivables as accounted for under the “Transfers and Servicing” accounting guidance.

[5] Weighted-average rate.

[6] Amount represents the combined authorized short-term borrowing limit the State Transcos have from FERC or state regulatory commissions.

[7] Amount represents the combined authorized short-term borrowing limit the State Transcos have from FERC or state regulatory commissions.

[8] In 2020, an increase in allowance for doubtful accounts was recognized in response to the anticipated impact of COVID-19 on the collectability of accounts receivable, which caused an increase in fees paid by the registrants. In 2021, due to higher than expected collections of accounts receivables, allowance for doubtful accounts was adjusted resulting in the issuance of credits to offset the higher fees previously paid and to lower subsequent fees paid.

[9] Includes $(121) million related to a forward equity purchase contract associated with the issuance of Equity Units.