Financing Activities (Details) - USD ($)		1 Months Ended	3 Months Ended						9 Months Ended
		Oct. 24, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Long-term Debt
Senior Unsecured Notes			$ 20,829,200,000						$ 20,829,200,000		$ 18,903,300,000
Pollution Control Bonds			1,516,500,000						1,516,500,000		1,643,800,000
Notes Payable			189,100,000						189,100,000		204,700,000
Securitization Bonds			1,059,400,000						1,059,400,000		1,111,400,000
Spent Nuclear Fuel Obligation	[1]		278,500,000						278,500,000		273,600,000
Junior Subordinated Notes	[2]		786,800,000						786,800,000		0
Other Long-term Debt			1,221,700,000						1,221,700,000		1,209,900,000
Total Long-term Debt Outstanding			25,881,200,000						25,881,200,000		23,346,700,000
Long-term Debt Due Within One Year			1,327,700,000						1,327,700,000		1,698,500,000
Long-term Debt			24,553,500,000						24,553,500,000		21,648,200,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								3,549,000,000.0
Repayments of Long-term Debt									1,023,500,000	$ 1,959,500,000
Short-term Debt:
Securitized Debt for Receivables	[4]		750,000,000.0						750,000,000.0		750,000,000.0
Commercial Paper			1,760,000,000.0						1,760,000,000.0		1,160,000,000.0
Total Short-term Debt			$ 2,510,000,000.0						$ 2,510,000,000.0		$ 1,910,000,000.0
Securitized Debt for Receivables	[4],[5]		2.56%						2.56%		2.16%
Comparative Accounts Receivable Information
Effective Interest Rates on Securitization of Accounts Receivable			2.37%			2.27%			2.56%	2.06%
Net Uncollectible Accounts Receivable Written Off			$ 8,800,000			$ 9,600,000			$ 19,800,000	$ 19,000,000.0
Customer Accounts Receivable Managed Portfolio
Accounts Receivable Retained Interest and Pledged as Collateral Less Uncollectible Accounts			923,300,000						923,300,000		$ 972,500,000
Total Principal Outstanding			750,000,000.0						750,000,000.0		750,000,000.0
Delinquent Securitized Accounts Receivable			43,900,000						43,900,000		50,300,000
Bad Debt Reserves Related to Securitization, Sale of Accounts Receivable			32,300,000						32,300,000		27,500,000
Unbilled Receivables Related to Securitization, Sale of Accounts Receivable			216,200,000						216,200,000		281,400,000
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			4,315,000,000.0			4,333,100,000			11,945,400,000	12,394,600,000
Financing Activities (Textuals)
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition			322,000,000						322,000,000		$ 317,000,000
Reacquired Pollution Controls Bonds Held by Trustees			574,000,000						$ 574,000,000
Maximum Percentage Debt to Capitalization									67.50%
Total Commitment from Bank Conduits to Finance Receivables			750,000,000						$ 750,000,000
Equity Units Issued									16,100,000
Per Unit Conversion for Equity Units			50						$ 50
Net Equity Units Issuance Proceeds									785,000,000
Principal Amounts of Junior Subordinated Debt			$ 1,000						$ 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%
Stockholders' Equity, Other			$ (500,000)	$ (2,500,000)	$ 55,600,000	(3,600,000)	$ 1,500,000	$ (16,900,000)
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],[6]								$ 805,000,000.0
Due Date	[6]								2024
Interest Rate (Percentage)	[6]		3.40%						3.40%
Pollution Control Bonds [Member] | Subsequent Event [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt		$ 240,000,000
Commercial Paper [Member]
Short-term Debt:
Weighted Average Interest Rate	[5]		2.36%						2.36%		2.96%
AEP Texas Inc. [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 4,146,500,000						$ 4,146,500,000		$ 3,881,300,000
Long-term Debt Due Within One Year			391,400,000						391,400,000		501,100,000
Long-term Debt			3,755,100,000						3,755,100,000		3,380,200,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 366,800,000	$ 231,700,000
Financing Activities (Textuals)
Maximum Percentage Debt to Capitalization									67.50%
AEP Texas Inc. [Member] | Utility [Member]
Maximum Interest Rate									3.43%	2.52%
Minimum Interest Rate									1.83%	1.81%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 390,700,000
Maximum Loans to Money Pool									0
Average Borrowings from Money Pool									261,800,000
Average Loans to Money Pool									0
Net Loans (Borrowings) to/from Money Pool			(74,800,000)						(74,800,000)
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									2.71%	2.25%
Average Interest Rate For Funds Loaned									0.00%	2.29%
AEP Texas Inc. [Member] | Nonutility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Loans to Money Pool									$ 8,000,000.0
Average Loans to Money Pool									7,700,000
Net Loans (Borrowings) to/from Money Pool			$ 7,700,000						$ 7,700,000
Maximum and Minimum Interest Rates
Maximum Interest Rate For Funds Loaned									3.02%	2.52%
Minimum Interest Rate for Funds Loaned									2.36%	1.83%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Loaned									2.70%	2.26%
AEP Texas Inc. [Member] | Pollution Control Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								$ 100,600,000
Due Date									2029
Interest Rate (Percentage)			2.60%						2.60%
AEP Texas Inc. [Member] | Pollution Control Bonds Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 100,600,000
Due Date									2029
Interest Rate (Percentage)			6.30%						6.30%
AEP Texas Inc. [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								$ 117,600,000
Due Date									2025
Interest Rate (Percentage)			2.06%						2.06%
AEP Texas Inc. [Member] | Securitization Bonds Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								$ 117,600,000
Due Date									2029
Interest Rate (Percentage)			2.29%						2.29%
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									$ 28,200,000
Due Date									2020
Interest Rate (Percentage)			1.98%						1.98%
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									$ 188,000,000.0
Due Date									2020
Interest Rate (Percentage)			5.31%						5.31%
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]								$ 300,000,000.0
Due Date									2049
Interest Rate (Percentage)			4.15%						4.15%
AEP Texas Inc. [Member] | Senior Unsecured Notes Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 50,000,000.0
Due Date									2019
Interest Rate (Percentage)			2.61%						2.61%
AEP Transmission Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 3,511,900,000						$ 3,511,900,000		2,823,000,000.0
Long-term Debt Due Within One Year			85,000,000.0						85,000,000.0		85,000,000.0
Long-term Debt			3,426,900,000						3,426,900,000		2,738,000,000.0
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									3.43%	2.52%
Minimum Interest Rate									1.83%	1.81%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 374,900,000
Maximum Loans to Money Pool									244,400,000
Average Borrowings from Money Pool									179,800,000
Average Loans to Money Pool									40,200,000
Net Loans (Borrowings) to/from Money Pool			$ 236,600,000						236,600,000
Authorized Short Term Borrowing Limit	[7]								$ 795,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed									2.72%	2.26%
Average Interest Rate For Funds Loaned									2.57%	2.04%
AEP Transmission Co [Member] | Direct Borrowing [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 1,300,000
Maximum Loans to Money Pool									117,600,000
Average Borrowings from Money Pool									1,300,000
Average Loans to Money Pool									63,400,000
Borrowings from Parent			1,300,000						1,300,000
Loans to Parent			$ 30,800,000						30,800,000
Authorized Short Term Borrowing Limit	[8]								$ 75,000,000.0
Maximum and Minimum Interest Rates
Maximum Interest Rate for Funds Borrowed									3.02%	2.52%
Minimum Interest Rate For Funds Borrowed									2.36%	1.76%
Maximum Interest Rate For Funds Loaned									3.02%	2.52%
Minimum Interest Rate for Funds Loaned									2.36%	1.76%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed									2.70%	2.26%
Average Interest Rate For Funds Loaned									2.70%	2.27%
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]								$ 350,000,000.0
Due Date									2049
Interest Rate (Percentage)			3.80%						3.80%
AEP Transmission 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]								$ 350,000,000.0
Due Date									2049
Interest Rate (Percentage)			3.15%						3.15%
Appalachian Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 4,362,900,000						$ 4,362,900,000		4,062,600,000
Long-term Debt Due Within One Year			215,600,000						215,600,000		430,700,000
Long-term Debt			4,147,300,000						4,147,300,000		3,631,900,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									180,400,000	$ 24,000,000.0
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			95,400,000						95,400,000		133,300,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			303,300,000			334,100,000			$ 978,500,000	1,079,200,000
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			1,200,000			1,800,000			$ 5,800,000	$ 5,100,000
Appalachian Power Co [Member] | Utility [Member]
Maximum Interest Rate									3.43%	2.52%
Minimum Interest Rate									1.83%	1.81%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 225,400,000
Maximum Loans to Money Pool									232,200,000
Average Borrowings from Money Pool									90,400,000
Average Loans to Money Pool									61,800,000
Net Loans (Borrowings) to/from Money Pool			$ (17,700,000)						(17,700,000)
Authorized Short Term Borrowing Limit									$ 600,000,000.0
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Borrowed									2.82%	2.22%
Average Interest Rate For Funds Loaned									2.73%	2.19%
Appalachian Power Co [Member] | Pollution Control Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								$ 86,000,000.0
Due Date									2024
Interest Rate (Percentage)			2.55%						2.55%
Appalachian Power Co [Member] | Pollution Control Bonds Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 86,000,000.0
Due Date									2019
Interest Rate (Percentage)			1.90%						1.90%
Appalachian Power Co [Member] | Pollution Control Bonds Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 70,000,000.0
Due Date									2019
Interest Rate (Percentage)			3.25%						3.25%
Appalachian Power Co [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 24,400,000
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	[3]								$ 400,000,000.0
Due Date									2049
Interest Rate (Percentage)			4.50%						4.50%
Indiana Michigan Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 3,031,500,000						$ 3,031,500,000		3,035,400,000
Long-term Debt Due Within One Year			147,400,000						147,400,000		155,400,000
Long-term Debt			2,884,100,000						2,884,100,000		2,880,000,000.0
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									73,600,000	$ 856,100,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			156,200,000						156,200,000		152,900,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			485,300,000			498,400,000			1,378,900,000	1,401,700,000
Financing Activities (Textuals)
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition			322,000,000						$ 322,000,000		317,000,000
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			2,400,000			2,500,000			$ 8,400,000	$ 6,800,000
Indiana Michigan Power Co [Member] | Utility [Member]
Maximum Interest Rate									3.43%	2.52%
Minimum Interest Rate									1.83%	1.81%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 120,400,000
Maximum Loans to Money Pool									66,000,000.0
Average Borrowings from Money Pool									53,100,000
Average Loans to Money Pool									17,200,000
Net Loans (Borrowings) to/from Money Pool			$ (89,200,000)						(89,200,000)
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									2.56%	2.16%
Average Interest Rate For Funds Loaned									2.73%	2.06%
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]								$ 62,800,000
Due Date									2023
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		4,000,000
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									$ 2,700,000
Due Date									2019
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									$ 4,300,000
Due Date									2019
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									$ 13,700,000
Due Date									2020
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									$ 17,900,000
Due Date									2021
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									$ 11,300,000
Due Date									2022
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									$ 16,000,000.0
Due Date									2022
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									$ 6,400,000
Due Date									2023
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%
Indiana Michigan Power Co [Member] | Pollution Control Bonds [Member] | Subsequent Event [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt		$ 25,000,000
Ohio Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 2,113,900,000						$ 2,113,900,000		1,716,600,000
Long-term Debt Due Within One Year			100,000						100,000		47,900,000
Long-term Debt			2,113,800,000						2,113,800,000		1,668,700,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									48,000,000.0	$ 397,000,000.0
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			337,500,000						337,500,000		395,200,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			602,600,000			695,200,000			1,746,100,000	2,046,900,000
Financing Activities (Textuals)
Reacquired Pollution Controls Bonds Held by Trustees			345,000,000						345,000,000
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			6,400,000			7,200,000			$ 22,100,000	$ 18,800,000
Ohio Power Co [Member] | Utility [Member]
Maximum Interest Rate									3.43%	2.52%
Minimum Interest Rate									1.83%	1.81%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 291,200,000
Maximum Loans to Money Pool									178,600,000
Average Borrowings from Money Pool									163,500,000
Average Loans to Money Pool									50,100,000
Net Loans (Borrowings) to/from Money Pool			$ (17,600,000)						(17,600,000)
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									2.80%	2.18%
Average Interest Rate For Funds Loaned									2.68%	2.47%
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] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 47,900,000
Due Date									2019
Interest Rate (Percentage)			2.05%						2.05%
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									2049
Interest Rate (Percentage)			4.00%						4.00%
Public Service Co Of Oklahoma [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 1,386,400,000						$ 1,386,400,000		1,287,000,000.0
Long-term Debt Due Within One Year			138,200,000						138,200,000		375,500,000
Long-term Debt			1,248,200,000						1,248,200,000		911,500,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									250,400,000	$ 300,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			149,400,000						149,400,000		109,700,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			451,500,000			454,900,000			$ 1,118,700,000	1,171,200,000
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			2,000,000.0			2,300,000			$ 6,200,000	$ 6,000,000.0
Public Service Co Of Oklahoma [Member] | Utility [Member]
Maximum Interest Rate									3.43%	2.52%
Minimum Interest Rate									1.83%	1.81%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 140,500,000
Maximum Loans to Money Pool									215,600,000
Average Borrowings from Money Pool									63,900,000
Average Loans to Money Pool									84,100,000
Net Loans (Borrowings) to/from Money Pool			$ 95,100,000						95,100,000
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									2.85%	2.25%
Average Interest Rate For Funds Loaned									2.48%	1.86%
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] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								$ 100,000,000.0
Due Date									2029
Interest Rate (Percentage)			3.91%						3.91%
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]								$ 150,000,000.0
Due Date									2034
Interest Rate (Percentage)			4.11%						4.11%
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								$ 100,000,000.0
Due Date									2049
Interest Rate (Percentage)			4.50%						4.50%
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes Four [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 250,000,000.0
Due Date									2019
Interest Rate (Percentage)			5.15%						5.15%
Southwestern Electric Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 2,656,900,000						$ 2,656,900,000		2,713,400,000
Long-term Debt Due Within One Year			121,200,000						121,200,000		59,700,000
Long-term Debt			2,535,700,000						2,535,700,000		2,653,700,000
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									58,200,000	$ 385,300,000
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			168,600,000						168,600,000		$ 150,300,000
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			480,700,000			512,600,000			$ 1,247,000,000.0	1,364,600,000
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			1,900,000			$ 2,600,000			$ 7,900,000	$ 6,600,000
Southwestern Electric Power Co [Member] | Utility [Member]
Maximum Interest Rate									3.43%	2.52%
Minimum Interest Rate									1.83%	1.81%
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits
Maximum Borrowings from Money Pool									$ 105,100,000
Maximum Loans to Money Pool									81,400,000
Average Borrowings from Money Pool									57,800,000
Average Loans to Money Pool									11,200,000
Net Loans (Borrowings) to/from Money Pool			6,400,000						6,400,000
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									2.74%	2.31%
Average Interest Rate For Funds Loaned									2.47%	1.87%
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									2,000,000.0
Net Loans (Borrowings) to/from Money Pool			$ 2,100,000						$ 2,100,000
Maximum and Minimum Interest Rates
Maximum Interest Rate For Funds Loaned									3.02%	2.52%
Minimum Interest Rate for Funds Loaned									2.36%	1.83%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool
Average Interest Rate For Funds Loaned									2.70%	2.26%
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] | Pollution Control Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 53,500,000
Due Date									2019
Interest Rate (Percentage)			1.60%						1.60%
AEP Generating Co [Member] | Pollution Control Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Proceeds from Issuance of Debt	[3]								$ 45,000,000.0
Due Date									2022
Interest Rate (Percentage)			1.35%						1.35%
AEP Generating Co [Member] | Pollution Control Bonds Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 45,000,000.0
Due Date									2019
Interest Rate (Variable)									Variable
AEP Energy [Member] | Notes Payable, Other Payables [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 100,000
Due Date									2019
Interest Rate (Percentage)			5.75%						5.75%
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]								$ 14,400,000
Due Date									2020
Interest Rate (Variable)									Variable
Transource Energy [Member] | OtherLongTermDebtTwo [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Repayments of Long-term Debt									$ 1,000,000.0
Due Date									2020
Interest Rate (Variable)									Varaible
Maximum [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]
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)
Stockholders' Equity, Other									$ 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 $322 million and $317 million as of September 30, 2019 and December 31, 2018, 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] See “Equity Units” section below for additional information.

[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.