Financing Activities (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		9 Months Ended
		Nov. 01, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Long-term Debt
Senior Unsecured Notes							$ 13,629.1
Pollution Control Bonds			$ 1,724.5		$ 1,724.5		1,784.8
Notes Payable			268.5		268.5		264.7
Securitization Bonds			1,737.6		1,737.6		2,024.0
Spent Nuclear Fuel Obligation	[1]		266.1		266.1		265.6
Other Long-term Debt			1,768.9		1,768.9		1,604.5
Total Long-term Debt Outstanding			19,704.7		19,704.7		19,572.7
Long-term Debt Due Within One Year			2,384.8		2,384.8		1,831.8
Long-term Debt			17,319.9		17,319.9		17,740.9
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				1,570.3
Retirements and Principal Payments					1,307.6	$ 2,131.4
Short-term Debt:
Securitized Debt for Receivables	[3]		750.0		750.0		675.0
Commercial Paper			728.3		728.3		125.0
Total Short-term Debt			$ 1,478.3		$ 1,478.3		$ 800.0
Securitized Debt for Receivables	[3],[4]		0.65%		0.65%		0.30%
Comparative Accounts Receivable Information
Effective Interest Rates on Securitization of Accounts Receivable			0.73%	0.30%	0.65%	0.28%
Net Uncollectible Accounts Receivable Written Off			$ 7.7	$ 13.5	$ 17.5	$ 27.5
Customer Accounts Receivable Managed Portfolio
Accounts Receivable Retained Interest and Pledged as Collateral Less Uncollectible Accounts			1,037.7		1,037.7		$ 924.8
Total Principal Outstanding			750.0		750.0		675.0
Delinquent Securitized Accounts Receivable			47.7		47.7		48.3
Bad Debt Reserves Related to Securitization, Sale of Accounts Receivable			27.8		27.8		17.5
Unbilled Receivables Related to Securitization, Sale of Accounts Receivable			297.1		297.1		357.8
Financing Activities (Textuals) [Abstract]
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition			309.0		309.0		$ 309.0
Repayments of Long-term Debt					1,307.6	2,131.4
Issuance of Long-term Debt	[2]				1,570.3
Reacquired Pollution Controls Bonds Held by Trustees			614.0		$ 614.0
Maximum Percentage Debt to Capitalization					67.50%
Total Commitment from Bank Conduits to Finance Receivables			750.0		$ 750.0
Includes Debt Included In Liabilities Held For Sale [Member]
Long-term Debt
Senior Unsecured Notes	[5]		14,073.9		14,073.9
Total Long-term Debt Outstanding	[5],[6]		19,839.5		19,839.5
Long-term Debt Due Within One Year	[5]		$ 2,519.6		$ 2,519.6
Commercial Paper [Member]
Short-term Debt:
Weighted Average Interest Rate	[4]		0.90%		0.90%		0.81%
AEP Subsidiaries [Member]
Long-term Debt
Long-term Debt Due Within One Year			$ 393.4		$ 393.4		$ 410.4
Long-term Debt			$ 1,727.6		1,727.6		1,971.4
AEP Subsidiaries [Member] | Notes Payable [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 5.1
Interest Rate (Variable)					Variable
Due Date					2017
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 5.1
Due Date					2017
AEP Subsidiaries [Member] | Notes Payable Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 0.1
Interest Rate (Percentage)			5.75%		5.75%
Due Date					2021
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 0.1
Interest Rate (Percentage)			5.75%		5.75%
Due Date					2021
AEP Generating Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 7.3
Interest Rate (Percentage)			6.33%		6.33%
Due Date					2037
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 7.3
Interest Rate (Percentage)			6.33%		6.33%
Due Date					2037
AEP Generation Resources [Member] | Pollution Control Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 60.0
Interest Rate (Variable)					Variable
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 60.0
Due Date					2016
AEP Texas Central Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 100.0
Interest Rate (Variable)					Variable
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 100.0
Due Date					2016
AEP Texas Central Co [Member] | OtherLongTermDebtTwo [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 125.0
Interest Rate (Variable)					Variable
Due Date					2019
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 125.0
Due Date					2019
AEP Texas Central Co [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 44.2
Interest Rate (Percentage)			6.25%		6.25%
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 44.2
Interest Rate (Percentage)			6.25%		6.25%
Due Date					2016
AEP Texas Central Co [Member] | Securitization Bonds Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 149.1
Interest Rate (Percentage)			5.17%		5.17%
Due Date					2018
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 149.1
Interest Rate (Percentage)			5.17%		5.17%
Due Date					2018
AEP Texas Central Co [Member] | Securitization Bonds Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 26.9
Interest Rate (Percentage)			0.88%		0.88%
Due Date					2017
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 26.9
Interest Rate (Percentage)			0.88%		0.88%
Due Date					2017
AEP Texas North Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 75.0
Interest Rate (Variable)					Variable
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 75.0
Due Date					2016
AEP Texas North Co [Member] | OtherLongTermDebtTwo [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 75.0
Interest Rate (Variable)					Variable
Due Date					2019
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 75.0
Due Date					2019
Appalachian Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 4,033.1		$ 4,033.1		3,930.7
Long-term Debt Due Within One Year			503.1		503.1		318.0
Long-term Debt			3,530.0		3,530.0		3,612.7
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					213.6	672.5
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			131.9		131.9		135.4
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			1.6	2.0	5.4	6.0
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			361.7	355.3	1,071.6	1,115.5
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 213.6	$ 672.5
Maximum Percentage Debt to Capitalization					67.50%
Appalachian Power Co [Member] | Utility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]
Maximum Borrowings from Money Pool					$ 286.9
Maximum Loans to Money Pool					25.7
Average Borrowings from Money Pool					165.5
Average Loans to Money Pool					24.9
Net Loans (Borrowings) to/from Money Pool			$ (59.7)		(59.7)
Authorized Short Term Borrowing Limit					$ 600.0
Maximum and Minimum Interest Rates
Maximum Interest Rate					0.91%	0.59%
Minimum Interest Rate					0.69%	0.39%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]
Average Interest Rate For Funds Borrowed					0.78%	0.46%
Average Interest Rate For Funds Loaned					0.79%	0.46%
Appalachian Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 125.0
Interest Rate (Variable)					Variable
Due Date					2019
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 125.0
Due Date					2019
Appalachian Power Co [Member] | Pollution Control Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 125.3
Retirements and Principal Payments					$ 125.3
Interest Rate (Variable)					Variable
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 125.3
Issuance of Long-term Debt	[2]				$ 125.3
Due Date					2016
Appalachian Power Co [Member] | Pollution Control Bonds Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 65.4
Interest Rate (Percentage)			1.70%		1.70%
Due Date					2020
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 65.4
Interest Rate (Percentage)			1.70%		1.70%
Due Date					2020
Appalachian Power Co [Member] | Pollution Control Bonds Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 65.3
Interest Rate (Percentage)			2.25%		2.25%
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 65.3
Interest Rate (Percentage)			2.25%		2.25%
Due Date					2016
Appalachian Power Co [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 23.0
Interest Rate (Percentage)			2.008%		2.008%
Due Date					2024
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 23.0
Interest Rate (Percentage)			2.008%		2.008%
Due Date					2024
Indiana Michigan Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 2,407.4		$ 2,407.4		2,000.0
Long-term Debt Due Within One Year			176.1		176.1		162.9
Long-term Debt			2,231.3		2,231.3		1,837.1
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					76.8	$ 178.5
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			152.5		152.5		134.8
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			2.0	2.2	5.6	6.6
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			448.0	401.5	1,220.2	1,192.1
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					76.8	$ 178.5
Reacquired Pollution Controls Bonds Held by Trustees			40.0		$ 40.0
Maximum Percentage Debt to Capitalization					67.50%
Indiana Michigan Power Co [Member] | Utility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]
Maximum Borrowings from Money Pool					$ 369.1
Maximum Loans to Money Pool					97.6
Average Borrowings from Money Pool					118.9
Average Loans to Money Pool					21.8
Net Loans (Borrowings) to/from Money Pool			$ (13.9)		(13.9)
Authorized Short Term Borrowing Limit					$ 500.0
Maximum and Minimum Interest Rates
Maximum Interest Rate					0.91%	0.59%
Minimum Interest Rate					0.69%	0.39%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]
Average Interest Rate For Funds Borrowed					0.73%	0.47%
Average Interest Rate For Funds Loaned					0.78%	0.46%
Indiana Michigan Power Co [Member] | Notes Payable [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 0.8
Interest Rate (Variable)					Variable
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 0.8
Due Date					2016
Indiana Michigan Power Co [Member] | Notes Payable [Member] | Subsequent Event [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments		$ 16.0
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt		$ 16.0
Indiana Michigan Power Co [Member] | Notes Payable Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 0.5
Interest Rate (Percentage)			2.12%		2.12%
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 0.5
Interest Rate (Percentage)			2.12%		2.12%
Due Date					2016
Indiana Michigan Power Co [Member] | Notes Payable Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 12.6
Interest Rate (Variable)					Variable
Due Date					2017
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 12.6
Due Date					2017
Indiana Michigan Power Co [Member] | Notes Payable Four [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 24.8
Interest Rate (Variable)					Variable
Due Date					2019
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 24.8
Due Date					2019
Indiana Michigan Power Co [Member] | Notes Payable Five [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 31.0
Interest Rate (Variable)					Variable
Due Date					2019
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 31.0
Due Date					2019
Indiana Michigan Power Co [Member] | Notes Payable Six [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 6.1
Interest Rate (Variable)					Variable
Due Date					2020
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 6.1
Due Date					2020
Indiana Michigan Power Co [Member] | Notes Payable Seven [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 87.9
Interest Rate (Variable)					Variable
Due Date					2020
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 87.9
Due Date					2020
Indiana Michigan Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 1.0
Interest Rate (Percentage)			6.00%		6.00%
Due Date					2025
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 1.0
Interest Rate (Percentage)			6.00%		6.00%
Due Date					2025
Indiana Michigan Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 400.0
Interest Rate (Percentage)			4.55%		4.55%
Due Date					2046
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 400.0
Interest Rate (Percentage)			4.55%		4.55%
Due Date					2046
Ohio Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 1,763.4		$ 1,763.4		2,157.7
Long-term Debt Due Within One Year			46.4		46.4		395.9
Long-term Debt			1,717.0		1,717.0		1,761.8
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					395.9	$ 131.5
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			407.1		407.1		351.4
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			8.1	8.5	23.4	23.2
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			750.9	670.7	2,011.2	1,949.0
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					395.9	$ 131.5
Reacquired Pollution Controls Bonds Held by Trustees			345.0		345.0
Ohio Power Co [Member] | Utility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]
Maximum Borrowings from Money Pool					227.9
Maximum Loans to Money Pool					379.2
Average Borrowings from Money Pool					137.8
Average Loans to Money Pool					251.1
Net Loans (Borrowings) to/from Money Pool			$ 0.2		0.2
Authorized Short Term Borrowing Limit					$ 400.0
Maximum and Minimum Interest Rates
Maximum Interest Rate					0.91%	0.59%
Minimum Interest Rate					0.69%	0.39%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]
Average Interest Rate For Funds Borrowed					0.85%	0.00%
Average Interest Rate For Funds Loaned					0.74%	0.47%
Ohio Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 0.1
Interest Rate (Percentage)			1.149%		1.149%
Due Date					2028
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 0.1
Interest Rate (Percentage)			1.149%		1.149%
Due Date					2028
Ohio Power Co [Member] | Securitization Bonds [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 45.8
Interest Rate (Percentage)			0.958%		0.958%
Due Date					2018
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 45.8
Interest Rate (Percentage)			0.958%		0.958%
Due Date					2018
Ohio Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 350.0
Interest Rate (Percentage)			6.00%		6.00%
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 350.0
Interest Rate (Percentage)			6.00%		6.00%
Due Date					2016
Public Service Co Of Oklahoma [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 1,286.2		$ 1,286.2		1,286.1
Long-term Debt Due Within One Year			125.5		125.5		275.4
Long-term Debt			1,160.7		1,160.7		1,010.7
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					150.3	$ 0.3
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			146.1		146.1		116.1
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			1.8	1.7	4.7	4.5
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			390.6	411.5	971.9	1,025.9
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 150.3	$ 0.3
Maximum Percentage Debt to Capitalization					67.50%
Public Service Co Of Oklahoma [Member] | Utility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]
Maximum Borrowings from Money Pool					$ 9.6
Maximum Loans to Money Pool					205.4
Average Borrowings from Money Pool					5.1
Average Loans to Money Pool					47.0
Net Loans (Borrowings) to/from Money Pool			$ 51.1		51.1
Authorized Short Term Borrowing Limit					$ 300.0
Maximum and Minimum Interest Rates
Maximum Interest Rate					0.91%	0.59%
Minimum Interest Rate					0.69%	0.39%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]
Average Interest Rate For Funds Borrowed					0.76%	0.49%
Average Interest Rate For Funds Loaned					0.81%	0.46%
Public Service Co Of Oklahoma [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 0.3
Interest Rate (Percentage)			3.00%		3.00%
Due Date					2027
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 0.3
Interest Rate (Percentage)			3.00%		3.00%
Due Date					2027
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 50.0
Interest Rate (Percentage)			3.05%		3.05%
Due Date					2026
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 50.0
Interest Rate (Percentage)			3.05%		3.05%
Due Date					2026
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes Two [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 100.0
Interest Rate (Percentage)			4.11%		4.11%
Due Date					2046
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 100.0
Interest Rate (Percentage)			4.11%		4.11%
Due Date					2046
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes Three [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 150.0
Interest Rate (Percentage)			6.15%		6.15%
Due Date					2016
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 150.0
Interest Rate (Percentage)			6.15%		6.15%
Due Date					2016
Southwestern Electric Power Co [Member]
Long-term Debt
Total Long-term Debt Outstanding			$ 2,674.0		$ 2,674.0		2,273.5
Long-term Debt Due Within One Year			354.0		354.0		3.3
Long-term Debt			2,320.0		2,320.0		2,270.2
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					3.3	$ 306.8
Accounts Receivable and Accrued Unbilled Revenues
Accounts Receivable and Accrued Unbilled Revenues			170.0		170.0		$ 151.8
Fees Paid to AEP Credit for Customer Accounts Receivable Sold
Fees Paid to AEP Credit for Customer Accounts Receivable Sold			2.1	2.0	5.3	5.3
Proceeds from Sale of Receivables
Proceeds from Sale of Receivables to AEP Credit			460.4	$ 468.0	1,183.9	1,222.3
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 3.3	$ 306.8
Maximum Percentage Debt to Capitalization					67.50%
Southwestern Electric Power Co [Member] | Utility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]
Maximum Borrowings from Money Pool					$ 249.4
Maximum Loans to Money Pool					308.2
Average Borrowings from Money Pool					171.8
Average Loans to Money Pool					302.8
Net Loans (Borrowings) to/from Money Pool			297.4		297.4
Authorized Short Term Borrowing Limit					$ 350.0
Maximum and Minimum Interest Rates
Maximum Interest Rate					0.91%	0.59%
Minimum Interest Rate					0.69%	0.39%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]
Average Interest Rate For Funds Borrowed					0.79%	0.46%
Average Interest Rate For Funds Loaned					0.91%	0.48%
Southwestern Electric Power Co [Member] | Nonutility [Member]
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]
Maximum Loans to Money Pool					$ 2.0
Average Loans to Money Pool					2.0
Net Loans To Borrowings From Nonutility Money Pool			$ 2.0		$ 2.0
Maximum and Minimum Interest Rates
Maximum Interest Rate					0.91%
Minimum Interest Rate					0.69%
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]
Average Interest Rate For Funds Loaned					0.79%
Southwestern Electric Power Co [Member] | Notes Payable [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Retirements and Principal Payments					$ 3.3
Interest Rate (Percentage)			4.58%		4.58%
Due Date					2032
Financing Activities (Textuals) [Abstract]
Repayments of Long-term Debt					$ 3.3
Interest Rate (Percentage)			4.58%		4.58%
Due Date					2032
Southwestern Electric Power Co [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 5.2
Interest Rate (Percentage)			3.50%		3.50%
Due Date					2023
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 5.2
Interest Rate (Percentage)			3.50%		3.50%
Due Date					2023
Southwestern Electric Power Co [Member] | Senior Unsecured Notes [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 400.0
Interest Rate (Percentage)			2.75%		2.75%
Due Date					2026
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 400.0
Interest Rate (Percentage)			2.75%		2.75%
Due Date					2026
Transource Missouri [Member] | Other Long Term Debt [Member]
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made
Issuances	[2]				$ 11.5
Interest Rate (Variable)					Variable
Due Date					2018
Financing Activities (Textuals) [Abstract]
Issuance of Long-term Debt	[2]				$ 11.5
Due Date					2018

[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 spent nuclear fuel 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 $309 million and $309 million as of September 30, 2016 and December 31, 2015, respectively, and are included in Spent Nuclear Fuel and Decommissioning Trusts on the balance sheets.

[2] 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.

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

[4] Weighted average rate.

[5] Amounts include debt related to the Lawrenceburg Plant that has been classified as Liabilities Held for Sale on the balance sheet. See “Gavin, Waterford, Darby and Lawrenceburg Plants (Generation & Marketing Segment)” section of Note 6 for additional information.

[6] Amounts include debt related to the Lawrenceburg Plant that has been classified as Liabilities Held for Sale on the balance sheet. See “Gavin, Waterford, Darby and Lawrenceburg Plants (Generation & Marketing Segment)” section of Note 6 for additional information.