Financing Activities (Details) - USD ($)		1 Months Ended	3 Months Ended								9 Months Ended
		Oct. 22, 2020	Sep. 30, 2020		Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019		Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Long-term Debt
Senior Unsecured Notes			$ 24,125,400,000								$ 24,125,400,000		$ 21,180,700,000
Pollution Control Bonds			1,936,100,000								1,936,100,000		1,998,800,000
Notes Payable			161,300,000								161,300,000		234,300,000
Securitization Bonds			751,600,000								751,600,000		1,025,100,000
Spent Nuclear Fuel Obligation	[1]		281,100,000								281,100,000		279,800,000
Junior Subordinated Notes	[2]		1,622,100,000								1,622,100,000		787,800,000
Other Long-term Debt			1,189,500,000								1,189,500,000		1,219,000,000.0
Total Long-term Debt Outstanding			30,067,100,000								30,067,100,000		26,725,500,000
Long-term Debt Due Within One Year			1,911,600,000								1,911,600,000		1,598,700,000
Long-term Debt			28,155,500,000								28,155,500,000		25,126,800,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										4,036,900,000
Repayments of Long-term Debt											$ 700,500,000	$ 1,023,500,000
Document Period End Date											Sep. 30, 2020
Short-term Debt:
Securitized Debt for Receivables	[4]		703,000,000.0								$ 703,000,000.0		710,000,000.0
Commercial Paper			650,000,000.0								650,000,000.0		2,110,000,000.0
364-Day Term Loan			1,000,000,000.0								1,000,000,000.0		0
COVID-19 Electricity Relief Program Loan	[5]		2,000,000.0								2,000,000.0		0
Notes Payable			42,000,000.0								42,000,000.0		18,300,000
Total Short-term Debt			$ 2,397,000,000.0								$ 2,397,000,000.0		$ 2,838,300,000
Securitized Debt for Receivables	[4],[6]		1.05%								1.05%		2.42%
Comparative Accounts Receivable Information
Effective Interest Rates on Securitization of Accounts Receivable			0.36%				2.37%				1.05%	2.56%
Net Uncollectible Accounts Receivable Written Off			$ 2,900,000				$ 8,800,000				$ 10,500,000	$ 19,800,000
Customer Accounts Receivable Managed Portfolio
Accounts Receivable Retained Interest and Pledged as Collateral Less Uncollectible Accounts			1,002,400,000								1,002,400,000		$ 841,800,000
Total Principal Outstanding			703,000,000.0								703,000,000.0		710,000,000.0
Delinquent Securitized Accounts Receivable			103,800,000								103,800,000		39,600,000
Bad Debt Reserves Related to Securitization, Sale of Accounts Receivable			52,700,000								52,700,000		32,100,000
Unbilled Receivables Related to Securitization, Sale of Accounts Receivable			227,400,000								227,400,000		266,800,000
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			4,066,400,000				4,315,000,000.0				11,307,900,000	$ 11,945,400,000
Financing Activities (Textuals)
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition			326,000,000								$ 326,000,000		$ 323,000,000
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			103,700,000		$ 1,600,000	$ 30,200,000	(500,000)	$ 2,500,000	$ 55,600,000
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]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 850,000,000.0
Due Date											2025
Interest Rate (Percentage)			1.30%								1.30%
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]										$ 400,000,000.0
Due Date											2030
Interest Rate (Percentage)			2.30%								2.30%
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											2050
Interest Rate (Percentage)			3.25%								3.25%
Commercial Paper [Member]
Short-term Debt:
Weighted Average Interest Rate	[6]		0.21%								0.21%		2.10%
364 Day Term Loan
Short-term Debt:
Weighted Average Interest Rate	[6]		0.75%								0.75%		0.00%
COVID 19 Electricity Relief Program Loan
Short-term Debt:
Weighted Average Interest Rate	[5],[6]		0.00%								0.00%		0.00%
Loans Payable [Member]
Short-term Debt:
Weighted Average Interest Rate	[6]		2.46%								2.46%		3.29%
AEP Texas Inc. [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 4,854,700,000								$ 4,854,700,000		$ 4,558,400,000
Long-term Debt Due Within One Year			87,800,000								87,800,000		392,100,000
Long-term Debt			4,766,900,000								4,766,900,000		4,166,300,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											356,500,000	$ 366,800,000
Short-term Debt:
COVID-19 Electricity Relief Program Loan	[5]		2,000,000.0								$ 2,000,000.0		$ 0
Financing Activities (Textuals)
Maximum Percentage Debt to Capitalization											67.50%
AEP Texas Inc. [Member] | Utility [Member]
Maximum Interest Rate											2.70%	3.43%
Minimum Interest Rate											0.33%	1.83%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 320,400,000
Maximum Loans to Money Pool											313,400,000
Average Borrowings from Money Pool											154,700,000
Average Loans to Money Pool											167,400,000
Net Loans (Borrowings) to/from Money Pool			141,300,000								141,300,000
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											1.55%	2.71%
Average Interest Rate For Funds Loaned											0.87%	0.00%
AEP Texas Inc. [Member] | Nonutility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Loans to Money Pool											$ 7,500,000
Average Loans to Money Pool											7,100,000
Net Loans (Borrowings) to/from Money Pool			$ 7,100,000								$ 7,100,000
Maximum and Minimum Interest Rates
Maximum Interest Rate For Funds Loaned											2.70%	3.02%
Minimum Interest Rate for Funds Loaned											0.33%	2.36%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Loaned											1.44%	2.70%
AEP Texas Inc. [Member] | Pollution Control Bond [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 60,000,000.0
Due Date											2023
Interest Rate (Percentage)			0.90%								0.90%
AEP Texas Inc. [Member] | Pollution Control Bond Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 50,600,000
Due Date											2020
Interest Rate (Percentage)			4.45%								4.45%
AEP Texas Inc. [Member] | Pollution Control Bond Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 60,000,000.0
Due Date											2020
Interest Rate (Percentage)			1.75%								1.75%
AEP Texas Inc. [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 28,700,000
Due Date											2020
Interest Rate (Percentage)			1.98%								1.98%
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											$ 202,600,000
Due Date											2020
Interest Rate (Percentage)			5.31%								5.31%
AEP Texas Inc. [Member] | Securitization Bonds Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 200,000
Due Date											2024
Interest Rate (Percentage)			2.85%								2.85%
AEP Texas Inc. [Member] | Securitization Bonds Four [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 14,400,000
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]										$ 600,000,000.0
Due Date											2030
Interest Rate (Percentage)			2.10%								2.10%
AEP Texas Inc. [Member] | COVID 19 Electricity Relief Program Loan
Short-term Debt:
Weighted Average Interest Rate	[5],[6]		0.00%								0.00%		0.00%
AEP Transmission Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 3,947,900,000								$ 3,947,900,000		$ 3,427,300,000
Long-term Debt			3,947,900,000								3,947,900,000		3,427,300,000
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			0.90%								0.90%
Maximum Percentage Debt to Capitalization											67.50%
AEP Transmission Co [Member] | Utility [Member]
Maximum Interest Rate											2.70%	3.43%
Minimum Interest Rate											0.33%	1.83%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 358,400,000
Maximum Loans to Money Pool											259,700,000
Average Borrowings from Money Pool											112,700,000
Average Loans to Money Pool											59,100,000
Net Loans (Borrowings) to/from Money Pool			$ (84,300,000)								(84,300,000)
Authorized Short Term Borrowing Limit	[7]										$ 820,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											1.63%	2.72%
Average Interest Rate For Funds Loaned											2.00%	2.57%
AEP Transmission Co [Member] | Direct Borrowing [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 1,400,000
Maximum Loans to Money Pool											195,800,000
Average Borrowings from Money Pool											1,300,000
Average Loans to Money Pool											128,700,000
Borrowings from Parent			1,200,000								1,200,000
Loans to Parent			$ 105,400,000								105,400,000
Authorized Short Term Borrowing Limit	[8]										$ 50,000,000.0
Maximum and Minimum Interest Rates
Maximum Interest Rate for Funds Borrowed											2.70%	3.02%
Minimum Interest Rate For Funds Borrowed											0.50%	2.36%
Maximum Interest Rate For Funds Loaned											2.70%	3.02%
Minimum Interest Rate for Funds Loaned											0.50%	2.36%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed											1.45%	2.70%
Average Interest Rate For Funds Loaned											1.40%	2.70%
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											$ 525,000,000.0
Due Date											2050
Interest Rate (Percentage)			3.65%								3.65%
Appalachian Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 4,833,300,000								$ 4,833,300,000		4,363,800,000
Long-term Debt Due Within One Year			518,300,000								518,300,000		215,600,000
Long-term Debt			4,315,000,000.0								4,315,000,000.0		4,148,200,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											90,300,000	$ 180,400,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			117,300,000								117,300,000		120,900,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			323,500,000				303,300,000				$ 961,800,000	978,500,000
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			2,000,000.0				1,200,000				$ 5,000,000.0	$ 5,800,000
Appalachian Power Co [Member] | Utility [Member]
Maximum Interest Rate											2.70%	3.43%
Minimum Interest Rate											0.33%	1.83%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 434,300,000
Maximum Loans to Money Pool											189,000,000.0
Average Borrowings from Money Pool											274,800,000
Average Loans to Money Pool											74,600,000
Net Loans (Borrowings) to/from Money Pool			$ 155,200,000								155,200,000
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											2.14%	2.82%
Average Interest Rate For Funds Loaned											0.99%	2.73%
Appalachian Power Co [Member] | Pollution Control Bond [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt											$ 65,400,000
Due Date											2025
Interest Rate (Percentage)			1.00%								1.00%
Appalachian Power Co [Member] | Pollution Control Bond Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 65,400,000
Due Date											2020
Interest Rate (Percentage)			1.70%								1.70%
Appalachian Power Co [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 24,900,000
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											2050
Interest Rate (Percentage)			3.70%								3.70%
Indiana Michigan Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 2,981,900,000								$ 2,981,900,000		3,050,200,000
Long-term Debt Due Within One Year			348,700,000								348,700,000		139,700,000
Long-term Debt			2,633,200,000								2,633,200,000		2,910,500,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											71,100,000	$ 73,600,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			184,300,000								184,300,000		141,800,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			532,300,000				485,300,000				1,443,600,000	1,378,900,000
Financing Activities (Textuals)
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition			326,000,000								$ 326,000,000		323,000,000
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			3,900,000				2,400,000				$ 9,300,000	$ 8,400,000
Indiana Michigan Power Co [Member] | Utility [Member]
Maximum Interest Rate											2.70%	3.43%
Minimum Interest Rate											0.33%	1.83%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 218,600,000
Maximum Loans to Money Pool											13,400,000
Average Borrowings from Money Pool											115,300,000
Average Loans to Money Pool											13,300,000
Net Loans (Borrowings) to/from Money Pool			$ (145,800,000)								(145,800,000)
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											1.30%	2.56%
Average Interest Rate For Funds Loaned											1.44%	2.73%
Indiana Michigan 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											$ 2,000,000.0
Due Date											2020
Interest Rate (Variable)											Variable
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		$ 5,000,000
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											$ 4,600,000
Due Date											2021
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payable Two [Member] | Subsequent Event [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt		$ 70,000,000
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											$ 14,900,000
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											$ 11,400,000
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											$ 18,700,000
Due Date											2023
Interest Rate (Variable)											Variable
Indiana Michigan Power Co [Member] | Notes Payable, Other Payables Six [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 18,200,000
Due Date											2024
Interest Rate (Variable)											Variable
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											$ 1,300,000
Due Date											2025
Interest Rate (Percentage)			6.00%								6.00%
Ohio Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 2,429,900,000								$ 2,429,900,000		2,082,000,000.0
Long-term Debt Due Within One Year			100,000								100,000		100,000
Long-term Debt			2,429,800,000								2,429,800,000		2,081,900,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											100,000	$ 48,000,000.0
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			394,300,000								394,300,000		330,300,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			666,000,000.0				602,600,000				1,793,000,000.0	1,746,100,000
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			9,800,000				6,400,000				$ 19,600,000	$ 22,100,000
Ohio Power Co [Member] | Utility [Member]
Maximum Interest Rate											2.70%	3.43%
Minimum Interest Rate											0.33%	1.83%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 353,900,000
Maximum Loans to Money Pool											32,800,000
Average Borrowings from Money Pool											158,300,000
Average Loans to Money Pool											25,200,000
Net Loans (Borrowings) to/from Money Pool			$ (215,900,000)								(215,900,000)
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											1.32%	2.80%
Average Interest Rate For Funds Loaned											2.06%	2.68%
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											$ 350,000,000.0
Due Date											2030
Interest Rate (Percentage)			2.60%								2.60%
Public Service Co Of Oklahoma [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 1,373,700,000								$ 1,373,700,000		1,386,200,000
Long-term Debt Due Within One Year			250,500,000								250,500,000		13,200,000
Long-term Debt			1,123,200,000								1,123,200,000		1,373,000,000.0
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											13,000,000.0	$ 250,400,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			122,000,000.0								122,000,000.0		101,100,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			369,200,000				451,500,000				$ 961,400,000	1,118,700,000
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			1,500,000				2,000,000.0				$ 3,800,000	$ 6,200,000
Public Service Co Of Oklahoma [Member] | Utility [Member]
Maximum Interest Rate											2.70%	3.43%
Minimum Interest Rate											0.33%	1.83%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 125,400,000
Maximum Loans to Money Pool											57,100,000
Average Borrowings from Money Pool											64,600,000
Average Loans to Money Pool											28,400,000
Net Loans (Borrowings) to/from Money Pool			$ (77,800,000)								(77,800,000)
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											1.24%	2.85%
Average Interest Rate For Funds Loaned											1.95%	2.48%
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											$ 300,000
Due Date											2027
Interest Rate (Percentage)			3.00%								3.00%
Public Service Co Of Oklahoma [Member] | Pollution Control Bond [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 12,700,000
Due Date											2020
Interest Rate (Percentage)			4.45%								4.45%
Southwestern Electric Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 2,637,300,000								$ 2,637,300,000		2,655,600,000
Long-term Debt Due Within One Year			6,200,000								6,200,000		121,200,000
Long-term Debt			2,631,100,000								2,631,100,000		2,534,400,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											19,700,000	$ 58,200,000
Short-term Debt:
Notes Payable			42,000,000.0								42,000,000.0		18,300,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			177,600,000								177,600,000		$ 125,200,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			$ 478,300,000				480,700,000				$ 1,225,300,000	1,247,000,000.0
Financing Activities (Textuals)
Stock Issued During Period, Shares, Reverse Stock Splits			2,048
Stock Issued During Period, Shares, Stock Splits			1
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			$ 2,800,000				1,900,000				$ 6,800,000	$ 7,900,000
Southwestern Electric Power Co [Member] | Utility [Member]
Maximum Interest Rate											2.70%	3.43%
Minimum Interest Rate											0.33%	1.83%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool											$ 178,900,000
Maximum Loans to Money Pool											0
Average Borrowings from Money Pool											113,600,000
Average Loans to Money Pool											0
Net Loans (Borrowings) to/from Money Pool			(71,800,000)								(71,800,000)
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											1.55%	2.74%
Average Interest Rate For Funds Loaned											0.00%	2.47%
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											2.70%	3.02%
Minimum Interest Rate for Funds Loaned											0.33%	2.36%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Loaned											1.44%	2.70%
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											$ 15,000,000.0
Due Date											2020
Interest Rate (Variable)											Variable
Southwestern Electric 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											2028
Interest Rate (Percentage)			4.68%								4.68%
Southwestern Electric Power Co [Member] | Loans Payable [Member]
Short-term Debt:
Weighted Average Interest Rate	[6]		2.46%								2.46%		3.29%
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											$ 125,000,000.0
Due Date											2022
Interest Rate (Variable)											Variable
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]										$ 4,400,000
Due Date											2020
Interest Rate (Variable)											Variable
Transource Energy [Member] | Other Long Term Debt Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]										$ 7,100,000
Due Date											2023
Interest Rate (Variable)											Variable
Transource Energy [Member] | Other Long Term Debt Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt											$ 148,600,000
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
Proceeds from Issuance of Debt	[3]										$ 150,000,000.0
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%
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											$ 120,600,000	$ 52,400,000
Additional Paid-in Capital [Member]
Financing Activities (Textuals)
Forward Equity Purchase Contract Included in Current and Noncurrent Liabilities as of September 30			$ 104,000,000.0	[9]	$ 2,600,000	$ 29,000,000.0	$ (500,000)	$ 3,100,000	$ 56,600,000	[10]
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 $326 million and $323 million as of September 30, 2020 and December 31, 2019, 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.(b)See “Equity Units” section below for additional information.

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

[5] Principal amount of loan shall not bear interest if paid in full by the maturity date. Unpaid principal after the maturity date will accrue interest of 2% per annum beginning the first day after the maturity date until all outstanding principal is paid.

[6] Weighted-average rate.

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

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

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

[10] Includes $(62) million related to a forward equity purchase contract associated with the issuance of Equity Units.