Benefit Plans 1 (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		$ 3,852.3	$ 3,407.3
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(728.0)	(719.8)
AEP Texas Inc. [Member]
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		192.1	147.1
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(57.2)	(81.1)
Appalachian Power Co [Member]
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		121.7	123.4
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(49.6)	(55.2)
Indiana Michigan Power Co [Member]
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		237.6	182.0
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(69.2)	(67.8)
Ohio Power Co [Member]
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		616.2	546.3
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(40.0)	(42.7)
Public Service Co Of Oklahoma [Member]
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		6.0	4.1
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(20.6)	(18.4)
Southwestern Electric Power Co [Member]
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		234.8	160.5
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		$ (94.2)	$ (86.2)
Pension Plans [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.50%	3.25%
Interest Crediting Rate		4.00%	4.00%
Rate of Compensation Increase	[1]	5.00%	4.95%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.25%	4.30%	3.65%
Interest Crediting Rate		4.00%	4.00%	4.00%
Expected Return on Plan Assets		5.75%	6.25%	6.00%
Rate of Compensation Increase	[2]	5.00%	4.95%	4.85%
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 5,236.8	$ 4,810.3
Service Cost		111.9	95.5	$ 97.6
Interest Cost		167.9	204.4	187.8
Actuarial (Gain) Loss		434.7	493.6
Plan Amendments		0.0	0.2
Benefit Payments		(406.8)	(367.2)
Participant Contributions		0.0	0.0
Medicare Subsidy		0.0	0.0
Benefit Obligation as of December 31		5,544.5	5,236.8	4,810.3
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		5,015.4	4,695.9
Actual Gain (Loss) on Plan Assets		832.4	681.1
Company Contributions	[3]	115.6	5.6
Participant Contributions		0.0	0.0
Benefit Payments		(406.8)	(367.2)
Fair Value of Plan Assets as of December 31		5,556.6	5,015.4	$ 4,695.9
Funded (Underfunded) Status as of December 31		12.1	(221.4)
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		93.5	0.0
Other Current Liabilities - Accrued Short-term Benefit Liability		(6.7)	(6.1)
Employee Benefits and Pension Obligations - Accrued Long-term Benefit Liability		(74.7)	(215.3)
Funded (Underfunded) Status		12.1	(221.4)
Components
Net Actuarial Loss		1,179.6	1,406.2
Prior Service Cost (Credit)		0.2	0.2
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(132.9)	108.6
Amortization of Actuarial Gain (Loss)		(93.7)	(57.6)
Prior Service (Credit) Cost		0.0	0.2
Amortization of Prior Service Credit (Cost)		0.0	0.0
Change for the Year		$ (226.6)	$ 51.2
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase	[1]	5.00%	4.95%
Company Contributions	[3]	$ 115.6	$ 5.6
Pension Plans [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		1,182.4	1,351.8
Pension Plans [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(0.5)	11.5
Pension Plans [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (2.1)	$ 43.1
Pension Plans [Member] | AEP Texas Inc. [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.50%	3.25%
Interest Crediting Rate		4.00%	4.00%
Rate of Compensation Increase	[1]	5.05%	5.00%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.25%	4.30%	3.65%
Interest Crediting Rate		4.00%	4.00%	4.00%
Expected Return on Plan Assets		5.75%	6.25%	6.00%
Rate of Compensation Increase	[2]	5.05%	5.00%	4.95%
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 441.2	$ 409.3
Service Cost		10.0	8.6	$ 9.2
Interest Cost		13.9	17.5	16.0
Actuarial (Gain) Loss		28.1	40.1
Plan Amendments		0.0	0.0
Benefit Payments		(40.0)	(34.3)
Participant Contributions		0.0	0.0
Benefit Obligation as of December 31		453.2	441.2	409.3
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		435.1	410.7
Actual Gain (Loss) on Plan Assets		67.2	58.3
Company Contributions		11.7	0.4
Participant Contributions		0.0	0.0
Benefit Payments		(40.0)	(34.3)
Fair Value of Plan Assets as of December 31		474.0	435.1	$ 410.7
Funded (Underfunded) Status as of December 31		20.8	(6.1)
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		24.7	0.0
Other Current Liabilities - Accrued Short-term Benefit Liability		(0.4)	(0.4)
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(3.5)	(5.7)
Funded (Underfunded) Status		20.8	(6.1)
Components
Net Actuarial Loss		160.5	184.7
Prior Service Cost (Credit)		0.0	0.0
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(16.4)	7.6
Amortization of Actuarial Gain (Loss)		(7.8)	(4.9)
Prior Service (Credit) Cost		0.0	0.0
Amortization of Prior Service Credit (Cost)		0.0	0.0
Change for the Year		$ (24.2)	$ 2.7
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase	[1]	5.05%	5.00%
Company Contributions		$ 11.7	$ 0.4
Pension Plans [Member] | AEP Texas Inc. [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		151.3	172.2
Pension Plans [Member] | AEP Texas Inc. [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		2.0	2.7
Pension Plans [Member] | AEP Texas Inc. [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ 7.2	$ 9.8
Pension Plans [Member] | Appalachian Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.50%	3.25%
Interest Crediting Rate		4.00%	4.00%
Rate of Compensation Increase	[1]	4.85%	4.80%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.25%	4.30%	3.65%
Interest Crediting Rate		4.00%	4.00%	4.00%
Expected Return on Plan Assets		5.75%	6.25%	6.00%
Rate of Compensation Increase	[2]	4.85%	4.75%	4.75%
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 647.2	$ 603.1
Service Cost		10.5	9.4	$ 9.3
Interest Cost		20.3	25.2	23.5
Actuarial (Gain) Loss		40.0	52.9
Plan Amendments		0.0	0.0
Benefit Payments		(47.2)	(43.4)
Participant Contributions		0.0	0.0
Medicare Subsidy		0.0	0.0
Benefit Obligation as of December 31		670.8	647.2	603.1
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		637.0	593.3
Actual Gain (Loss) on Plan Assets		104.5	87.1
Company Contributions		7.0	0.0
Participant Contributions		0.0	0.0
Benefit Payments		(47.2)	(43.4)
Fair Value of Plan Assets as of December 31		701.3	637.0	$ 593.3
Funded (Underfunded) Status as of December 31		30.5	(10.2)
Benefit Amounts Recognized on the Balance Sheets
Employee Benefits and Pension Assets - Prepaid Benefit Costs		31.0	0.0
Other Current Liabilities - Accrued Short-term Benefit Liability		0.0	0.0
Employee Benefits and Pension Obligations - Accrued Long-term Benefit Liability		(0.5)	(10.2)
Funded (Underfunded) Status		30.5	(10.2)
Components
Net Actuarial Loss		126.3	168.3
Prior Service Cost (Credit)		0.0	0.0
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(30.8)	3.1
Amortization of Actuarial Gain (Loss)		(11.2)	(7.0)
Prior Service (Credit) Cost		0.0	0.0
Amortization of Prior Service Credit (Cost)		0.0	0.0
Change for the Year		$ (42.0)	$ (3.9)
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase	[1]	4.85%	4.80%
Company Contributions		$ 7.0	$ 0.0
Pension Plans [Member] | Appalachian Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		124.7	166.3
Pension Plans [Member] | Appalachian Power Co [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		0.3	0.3
Pension Plans [Member] | Appalachian Power Co [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ 1.3	$ 1.7
Pension Plans [Member] | Indiana Michigan Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.50%	3.25%
Interest Crediting Rate		4.00%	4.00%
Rate of Compensation Increase	[1]	5.00%	4.95%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.25%	4.30%	3.65%
Interest Crediting Rate		4.00%	4.00%	4.00%
Expected Return on Plan Assets		5.75%	6.25%	6.00%
Rate of Compensation Increase	[2]	5.00%	4.95%	4.90%
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 616.1	$ 567.0
Service Cost		15.4	13.4	$ 13.6
Interest Cost		19.7	23.8	22.1
Actuarial (Gain) Loss		44.3	49.8
Plan Amendments		0.0	0.0
Benefit Payments		(42.2)	(37.9)
Participant Contributions		0.0	0.0
Benefit Obligation as of December 31		653.3	616.1	567.0
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		630.5	583.8
Actual Gain (Loss) on Plan Assets		103.3	84.6
Company Contributions		6.5	0.0
Participant Contributions		0.0	0.0
Benefit Payments		(42.2)	(37.9)
Fair Value of Plan Assets as of December 31		698.1	630.5	$ 583.8
Funded (Underfunded) Status as of December 31		44.8	14.4
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		46.5	15.8
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(1.7)	(1.4)
Funded (Underfunded) Status		44.8	14.4
Components
Net Actuarial Loss		39.5	76.0
Prior Service Cost (Credit)		0.0	0.0
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(25.7)	2.0
Amortization of Actuarial Gain (Loss)		(10.8)	(6.6)
Prior Service (Credit) Cost		0.0	0.0
Amortization of Prior Service Credit (Cost)		0.0	0.0
Change for the Year		$ (36.5)	$ (4.6)
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase	[1]	5.00%	4.95%
Company Contributions		$ 6.5	$ 0.0
Pension Plans [Member] | Indiana Michigan Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		40.3	73.7
Pension Plans [Member] | Indiana Michigan Power Co [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(0.1)	0.5
Pension Plans [Member] | Indiana Michigan Power Co [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (0.7)	$ 1.8
Pension Plans [Member] | Ohio Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.50%	3.25%
Interest Crediting Rate		4.00%	4.00%
Rate of Compensation Increase	[1]	5.25%	5.15%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.25%	4.30%	3.65%
Interest Crediting Rate		4.00%	4.00%	4.00%
Expected Return on Plan Assets		5.75%	6.25%	6.00%
Rate of Compensation Increase	[2]	5.25%	5.20%	5.00%
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 487.8	$ 453.9
Service Cost		9.7	7.9	$ 7.7
Interest Cost		15.4	19.1	17.7
Actuarial (Gain) Loss		33.4	40.5
Plan Amendments		0.0	0.0
Benefit Payments		(36.0)	(33.6)
Participant Contributions		0.0	0.0
Medicare Subsidy		0.0	0.0
Benefit Obligation as of December 31		510.3	487.8	453.9
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		499.1	466.1
Actual Gain (Loss) on Plan Assets		79.9	66.6
Company Contributions		0.1	0.0
Participant Contributions		0.0	0.0
Benefit Payments		(36.0)	(33.6)
Fair Value of Plan Assets as of December 31		543.1	499.1	$ 466.1
Funded (Underfunded) Status as of December 31		32.8	11.3
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		33.3	11.7
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(0.5)	(0.4)
Funded (Underfunded) Status		32.8	11.3
Components
Net Actuarial Loss		150.0	178.7
Prior Service Cost (Credit)		0.0	0.0
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(20.2)	3.3
Amortization of Actuarial Gain (Loss)		(8.5)	(5.3)
Prior Service (Credit) Cost		0.0	0.0
Amortization of Prior Service Credit (Cost)		0.0	0.0
Change for the Year		$ (28.7)	$ (2.0)
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase	[1]	5.25%	5.15%
Company Contributions		$ 0.1	$ 0.0
Pension Plans [Member] | Ohio Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ 150.0	$ 178.7
Pension Plans [Member] | Public Service Co Of Oklahoma [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.50%	3.25%
Interest Crediting Rate		4.00%	4.00%
Rate of Compensation Increase	[1]	5.05%	5.05%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.25%	4.30%	3.65%
Interest Crediting Rate		4.00%	4.00%	4.00%
Expected Return on Plan Assets		5.75%	6.25%	6.00%
Rate of Compensation Increase	[2]	5.05%	5.05%	4.90%
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 267.5	$ 253.8
Service Cost		7.3	6.5	$ 7.0
Interest Cost		8.5	10.6	9.9
Actuarial (Gain) Loss		17.7	16.8
Plan Amendments		0.0	0.0
Benefit Payments		(21.1)	(20.2)
Participant Contributions		0.0	0.0
Benefit Obligation as of December 31		279.9	267.5	253.8
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		276.2	261.2
Actual Gain (Loss) on Plan Assets		44.6	34.7
Company Contributions		0.1	0.5
Participant Contributions		0.0	0.0
Benefit Payments		(21.1)	(20.2)
Fair Value of Plan Assets as of December 31		299.8	276.2	$ 261.2
Funded (Underfunded) Status as of December 31		19.9	8.7
Benefit Amounts Recognized on the Balance Sheets
Employee Benefits and Pension Assets - Prepaid Benefit Costs		21.9	10.6
Other Current Liabilities - Accrued Short-term Benefit Liability		(0.1)	(0.1)
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		(1.9)	(1.8)
Funded (Underfunded) Status		19.9	8.7
Components
Net Actuarial Loss		55.9	73.0
Prior Service Cost (Credit)		0.0	0.0
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(12.4)	(1.7)
Amortization of Actuarial Gain (Loss)		(4.7)	(2.9)
Prior Service (Credit) Cost		0.0	0.0
Amortization of Prior Service Credit (Cost)		0.0	0.0
Change for the Year		$ (17.1)	$ (4.6)
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase	[1]	5.05%	5.05%
Company Contributions		$ 0.1	$ 0.5
Pension Plans [Member] | Public Service Co Of Oklahoma [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ 55.9	$ 73.0
Pension Plans [Member] | Southwestern Electric Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.50%	3.25%
Interest Crediting Rate		4.00%	4.00%
Rate of Compensation Increase	[1]	4.90%	4.90%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.25%	4.30%	3.65%
Interest Crediting Rate		4.00%	4.00%	4.00%
Expected Return on Plan Assets		5.75%	6.25%	6.00%
Rate of Compensation Increase	[2]	4.90%	4.90%	4.85%
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 314.2	$ 291.4
Service Cost		9.9	8.6	$ 9.3
Interest Cost		10.2	12.4	11.3
Actuarial (Gain) Loss		27.4	25.5
Plan Amendments		0.0	0.0
Benefit Payments		(27.2)	(23.7)
Participant Contributions		0.0	0.0
Benefit Obligation as of December 31		334.5	314.2	291.4
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		296.9	281.0
Actual Gain (Loss) on Plan Assets		48.2	39.5
Company Contributions		9.0	0.1
Participant Contributions		0.0	0.0
Benefit Payments		(27.2)	(23.7)
Fair Value of Plan Assets as of December 31		326.9	296.9	$ 281.0
Funded (Underfunded) Status as of December 31		(7.6)	(17.3)
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		0.0	0.0
Other Current Liabilities - Accrued Short-term Benefit Liability		(0.1)	(0.1)
Employee Benefits and Pension Obligations - Accrued Long-term Benefit Liability		(7.5)	(17.2)
Funded (Underfunded) Status		(7.6)	(17.3)
Components
Net Actuarial Loss		86.9	97.8
Prior Service Cost (Credit)		0.0	0.0
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(5.2)	3.8
Amortization of Actuarial Gain (Loss)		(5.7)	(3.4)
Prior Service (Credit) Cost		0.0	0.0
Amortization of Prior Service Credit (Cost)		0.0	0.0
Change for the Year		$ (10.9)	$ 0.4
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase	[1]	4.90%	4.90%
Company Contributions		$ 9.0	$ 0.1
Pension Plans [Member] | Southwestern Electric Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		86.9	97.8
Pension Plans [Member] | Southwestern Electric Power Co [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		0.0	0.0
Pension Plans [Member] | Southwestern Electric Power Co [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ 0.0	0.0
Pension Plans [Member] | Minimum [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		3.00%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		3.00%
Pension Plans [Member] | Minimum [Member] | AEP Texas Inc. [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		3.00%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		3.00%
Pension Plans [Member] | Minimum [Member] | Appalachian Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		3.00%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		3.00%
Pension Plans [Member] | Minimum [Member] | Indiana Michigan Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		3.00%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		3.00%
Pension Plans [Member] | Minimum [Member] | Ohio Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		3.00%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		3.00%
Pension Plans [Member] | Minimum [Member] | Public Service Co Of Oklahoma [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		3.00%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		3.00%
Pension Plans [Member] | Minimum [Member] | Southwestern Electric Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		3.00%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		3.00%
Pension Plans [Member] | Maximum [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		11.50%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		11.50%
Pension Plans [Member] | Maximum [Member] | AEP Texas Inc. [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		11.50%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		11.50%
Pension Plans [Member] | Maximum [Member] | Appalachian Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		11.50%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		11.50%
Pension Plans [Member] | Maximum [Member] | Indiana Michigan Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		11.50%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		11.50%
Pension Plans [Member] | Maximum [Member] | Ohio Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		11.50%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		11.50%
Pension Plans [Member] | Maximum [Member] | Public Service Co Of Oklahoma [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		11.50%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		11.50%
Pension Plans [Member] | Maximum [Member] | Southwestern Electric Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Rate of Compensation Increase		11.50%
Benefit Plans (Textuals) [Abstract]
Rate of Compensation Increase		11.50%
Qualified Pension Plans [Member]
Change in Fair Value of Plan Assets
Company Contributions		$ 110.0	0.0
Benefit Plans (Textuals) [Abstract]
Company Contributions		110.0	0.0
Nonqualified Pension Plans [Member]
Change in Benefit Obligation
Benefit Obligation as of December 31		81.4
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		0.0
Company Contributions		6.0	6.0
Fair Value of Plan Assets as of December 31		0.0	0.0
Benefit Plans (Textuals) [Abstract]
Company Contributions		6.0	6.0
Nonqualified Pension Plans [Member] | AEP Texas Inc. [Member]
Change in Benefit Obligation
Benefit Obligation as of December 31		3.9
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		0.0
Fair Value of Plan Assets as of December 31		0.0	0.0
Nonqualified Pension Plans [Member] | Appalachian Power Co [Member]
Change in Benefit Obligation
Benefit Obligation as of December 31		0.5
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		0.0
Fair Value of Plan Assets as of December 31		0.0	0.0
Nonqualified Pension Plans [Member] | Indiana Michigan Power Co [Member]
Change in Benefit Obligation
Benefit Obligation as of January 1		1.5
Benefit Obligation as of December 31		1.7	1.5
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		0.0
Fair Value of Plan Assets as of December 31		0.0	0.0
Nonqualified Pension Plans [Member] | Ohio Power Co [Member]
Change in Benefit Obligation
Benefit Obligation as of January 1		0.4
Benefit Obligation as of December 31		0.6	0.4
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		0.0
Fair Value of Plan Assets as of December 31		0.0	0.0
Nonqualified Pension Plans [Member] | Public Service Co Of Oklahoma [Member]
Change in Benefit Obligation
Benefit Obligation as of January 1		1.9
Benefit Obligation as of December 31		2.0	1.9
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		0.0
Fair Value of Plan Assets as of December 31		0.0	0.0
Nonqualified Pension Plans [Member] | Southwestern Electric Power Co [Member]
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		0.0
Fair Value of Plan Assets as of December 31		$ 0.0	$ 0.0
Other Postretirement Benefit Plans [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.55%	3.30%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.30%	4.30%	3.60%
Expected Return on Plan Assets		5.50%	6.25%	6.00%
Health Care Trend Rates
Initial		6.50%	6.00%
Ultimate		4.50%	4.50%
Year Ultimate Reached		2029	2026
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 1,225.4	$ 1,194.5
Service Cost		10.0	9.5	$ 11.6
Interest Cost		39.8	50.5	47.4
Actuarial (Gain) Loss		39.3	58.8
Plan Amendments		(11.4)	(11.0)
Benefit Payments		(131.0)	(113.0)
Participant Contributions		38.2	35.5
Medicare Subsidy		0.6	0.6
Benefit Obligation as of December 31		1,210.9	1,225.4	1,194.5
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		1,781.8	1,534.2
Actual Gain (Loss) on Plan Assets		253.0	321.0
Company Contributions	[3]	4.7	4.1
Participant Contributions		38.2	35.5
Benefit Payments		(131.0)	(113.0)
Fair Value of Plan Assets as of December 31		1,946.7	1,781.8	$ 1,534.2
Funded (Underfunded) Status as of December 31		735.8	556.4
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		771.9	590.8
Other Current Liabilities - Accrued Short-term Benefit Liability		(2.4)	(2.6)
Employee Benefits and Pension Obligations - Accrued Long-term Benefit Liability		(33.7)	(31.8)
Funded (Underfunded) Status		735.8	556.4
Components
Net Actuarial Loss		101.9	225.8
Prior Service Cost (Credit)		(227.3)	(285.7)
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(118.0)	(171.9)
Amortization of Actuarial Gain (Loss)		(5.9)	(22.1)
Prior Service (Credit) Cost		(11.4)	(7.6)
Amortization of Prior Service Credit (Cost)		69.8	69.1
Change for the Year		(65.5)	(132.5)
Benefit Plans (Textuals) [Abstract]
Company Contributions	[3]	4.7	4.1
Other Postretirement Benefit Plans [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(99.0)	(46.8)
Other Postretirement Benefit Plans [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(5.5)	(2.7)
Other Postretirement Benefit Plans [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (20.9)	$ (10.4)
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.55%	3.30%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.30%	4.30%	3.60%
Expected Return on Plan Assets		5.50%	6.25%	6.00%
Health Care Trend Rates
Initial		6.50%	6.00%
Ultimate		4.50%	4.50%
Year Ultimate Reached		2029	2026
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 97.8	$ 95.9
Service Cost		0.8	0.8	$ 0.9
Interest Cost		3.2	4.0	3.8
Actuarial (Gain) Loss		2.4	3.9
Plan Amendments		(1.0)	(0.9)
Benefit Payments		(10.0)	(8.8)
Participant Contributions		3.1	2.9
Benefit Obligation as of December 31		96.3	97.8	95.9
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		148.1	129.9
Actual Gain (Loss) on Plan Assets		21.1	24.0
Company Contributions		0.0	0.1
Participant Contributions		3.1	2.9
Benefit Payments		(10.0)	(8.8)
Fair Value of Plan Assets as of December 31		162.3	148.1	$ 129.9
Funded (Underfunded) Status as of December 31		66.0	50.3
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		66.0	50.3
Other Current Liabilities - Accrued Short-term Benefit Liability		0.0	0.0
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		0.0	0.0
Funded (Underfunded) Status		66.0	50.3
Components
Net Actuarial Loss		12.3	23.5
Prior Service Cost (Credit)		(19.3)	(24.2)
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(10.7)	(12.7)
Amortization of Actuarial Gain (Loss)		(0.5)	(1.8)
Prior Service (Credit) Cost		(1.0)	(0.6)
Amortization of Prior Service Credit (Cost)		5.9	5.9
Change for the Year		(6.3)	(9.2)
Benefit Plans (Textuals) [Abstract]
Company Contributions		0.0	0.1
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(6.3)	(0.2)
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(0.1)	(0.1)
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (0.6)	$ (0.4)
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.55%	3.30%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.30%	4.30%	3.60%
Expected Return on Plan Assets		5.50%	6.25%	6.00%
Health Care Trend Rates
Initial		6.50%	6.00%
Ultimate		4.50%	4.50%
Year Ultimate Reached		2029	2026
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 203.5	$ 205.5
Service Cost		1.0	1.0	$ 1.1
Interest Cost		6.6	8.7	8.2
Actuarial (Gain) Loss		5.6	4.7
Plan Amendments		(1.8)	(1.7)
Benefit Payments		(23.2)	(20.8)
Participant Contributions		6.3	5.9
Medicare Subsidy		0.2	0.2
Benefit Obligation as of December 31		198.2	203.5	205.5
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		271.0	238.4
Actual Gain (Loss) on Plan Assets		36.8	45.3
Company Contributions		2.1	2.2
Participant Contributions		6.3	5.9
Benefit Payments		(23.2)	(20.8)
Fair Value of Plan Assets as of December 31		293.0	271.0	$ 238.4
Funded (Underfunded) Status as of December 31		94.8	67.5
Benefit Amounts Recognized on the Balance Sheets
Employee Benefits and Pension Assets - Prepaid Benefit Costs		119.1	92.0
Other Current Liabilities - Accrued Short-term Benefit Liability		(1.8)	(2.0)
Employee Benefits and Pension Obligations - Accrued Long-term Benefit Liability		(22.5)	(22.5)
Funded (Underfunded) Status		94.8	67.5
Components
Net Actuarial Loss		11.1	28.8
Prior Service Cost (Credit)		(33.2)	(41.6)
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(16.8)	(26.4)
Amortization of Actuarial Gain (Loss)		(0.9)	(3.7)
Prior Service (Credit) Cost		(1.8)	(1.3)
Amortization of Prior Service Credit (Cost)		10.2	10.1
Change for the Year		(9.3)	(21.3)
Benefit Plans (Textuals) [Abstract]
Company Contributions		2.1	2.2
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(10.3)	(5.5)
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(2.5)	(1.5)
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (9.3)	$ (5.8)
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.55%	3.30%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.30%	4.30%	3.60%
Expected Return on Plan Assets		5.50%	6.25%	6.00%
Health Care Trend Rates
Initial		6.50%	6.00%
Ultimate		4.50%	4.50%
Year Ultimate Reached		2029	2026
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 142.9	$ 138.3
Service Cost		1.4	1.4	$ 1.6
Interest Cost		4.7	5.8	5.4
Actuarial (Gain) Loss		5.1	8.1
Plan Amendments		(1.6)	(1.5)
Benefit Payments		(15.9)	(13.6)
Participant Contributions		4.8	4.4
Benefit Obligation as of December 31		141.4	142.9	138.3
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		216.3	187.3
Actual Gain (Loss) on Plan Assets		33.0	38.2
Company Contributions		0.0	0.0
Participant Contributions		4.8	4.4
Benefit Payments		(15.9)	(13.6)
Fair Value of Plan Assets as of December 31		238.2	216.3	$ 187.3
Funded (Underfunded) Status as of December 31		96.8	73.4
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		96.8	73.4
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		0.0	0.0
Funded (Underfunded) Status		96.8	73.4
Components
Net Actuarial Loss		15.6	32.7
Prior Service Cost (Credit)		(31.0)	(39.0)
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(16.4)	(19.3)
Amortization of Actuarial Gain (Loss)		(0.7)	(2.7)
Prior Service (Credit) Cost		(1.5)	(1.0)
Amortization of Prior Service Credit (Cost)		9.5	9.4
Change for the Year		(9.1)	(13.6)
Benefit Plans (Textuals) [Abstract]
Company Contributions		0.0	0.0
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(14.6)	(6.2)
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(0.2)	0.0
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (0.6)	$ (0.1)
Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.55%	3.30%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.30%	4.30%	3.60%
Expected Return on Plan Assets		5.50%	6.25%	6.00%
Health Care Trend Rates
Initial		6.50%	6.00%
Ultimate		4.50%	4.50%
Year Ultimate Reached		2029	2026
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 130.2	$ 129.5
Service Cost		0.9	0.8	$ 0.9
Interest Cost		4.2	5.5	5.1
Actuarial (Gain) Loss		3.1	4.9
Plan Amendments		(1.3)	(1.2)
Benefit Payments		(15.0)	(13.5)
Participant Contributions		4.3	4.1
Medicare Subsidy		0.0	0.1
Benefit Obligation as of December 31		126.4	130.2	129.5
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		197.1	175.4
Actual Gain (Loss) on Plan Assets		26.6	31.1
Company Contributions		0.0	0.0
Participant Contributions		4.3	4.1
Benefit Payments		(15.0)	(13.5)
Fair Value of Plan Assets as of December 31		213.0	197.1	$ 175.4
Funded (Underfunded) Status as of December 31		86.6	66.9
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		86.6	66.9
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		0.0	0.0
Funded (Underfunded) Status		86.6	66.9
Components
Net Actuarial Loss		3.6	17.2
Prior Service Cost (Credit)		(22.9)	(28.6)
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(12.9)	(15.8)
Amortization of Actuarial Gain (Loss)		(0.7)	(2.5)
Prior Service (Credit) Cost		(1.3)	(0.8)
Amortization of Prior Service Credit (Cost)		7.0	6.9
Change for the Year		(7.9)	(12.2)
Benefit Plans (Textuals) [Abstract]
Company Contributions		0.0	0.0
Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (19.3)	$ (11.4)
Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.55%	3.30%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.30%	4.30%	3.60%
Expected Return on Plan Assets		5.50%	6.25%	6.00%
Health Care Trend Rates
Initial		6.50%	6.00%
Ultimate		4.50%	4.50%
Year Ultimate Reached		2029	2026
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 64.7	$ 62.3
Service Cost		0.7	0.6	$ 0.7
Interest Cost		2.1	2.6	2.5
Actuarial (Gain) Loss		1.9	3.8
Plan Amendments		(0.7)	(0.7)
Benefit Payments		(6.8)	(5.9)
Participant Contributions		2.1	2.0
Benefit Obligation as of December 31		64.0	64.7	62.3
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		98.0	84.3
Actual Gain (Loss) on Plan Assets		14.5	17.6
Company Contributions		0.0	0.0
Participant Contributions		2.1	2.0
Benefit Payments		(6.8)	(5.9)
Fair Value of Plan Assets as of December 31		107.8	98.0	$ 84.3
Funded (Underfunded) Status as of December 31		43.8	33.3
Benefit Amounts Recognized on the Balance Sheets
Employee Benefits and Pension Assets - Prepaid Benefit Costs		43.8	33.3
Other Current Liabilities - Accrued Short-term Benefit Liability		0.0	0.0
Deferred Credits and Other Noncurrent Liabilities - Accrued Long-term Benefit Liability		0.0	0.0
Funded (Underfunded) Status		43.8	33.3
Components
Net Actuarial Loss		10.5	18.2
Prior Service Cost (Credit)		(14.1)	(17.8)
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(7.4)	(8.9)
Amortization of Actuarial Gain (Loss)		(0.3)	(1.2)
Prior Service (Credit) Cost		(0.7)	(0.5)
Amortization of Prior Service Credit (Cost)		4.4	4.3
Change for the Year		(4.0)	(6.3)
Benefit Plans (Textuals) [Abstract]
Company Contributions		0.0	0.0
Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (3.6)	$ 0.4
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member]
Actuarial Assumptions for Benefit Obligations
Discount Rate		2.55%	3.30%
Actuarial Assumptions for Net Periodic Benefit Costs
Discount Rate		3.30%	4.30%	3.60%
Expected Return on Plan Assets		5.50%	6.25%	6.00%
Health Care Trend Rates
Initial		6.50%	6.00%
Ultimate		4.50%	4.50%
Year Ultimate Reached		2029	2026
Change in Benefit Obligation
Benefit Obligation as of January 1		$ 77.4	$ 72.7
Service Cost		0.8	0.8	$ 0.9
Interest Cost		2.5	3.1	2.8
Actuarial (Gain) Loss		2.5	6.0
Plan Amendments		(0.8)	(0.8)
Benefit Payments		(7.7)	(6.6)
Participant Contributions		2.4	2.2
Benefit Obligation as of December 31		77.1	77.4	72.7
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1		117.2	98.5
Actual Gain (Loss) on Plan Assets		18.0	23.1
Company Contributions		0.0	0.0
Participant Contributions		2.4	2.2
Benefit Payments		(7.7)	(6.6)
Fair Value of Plan Assets as of December 31		129.9	117.2	$ 98.5
Funded (Underfunded) Status as of December 31		52.8	39.8
Benefit Amounts Recognized on the Balance Sheets
Deferred Charges and Other Noncurrent Assets - Prepaid Benefit Costs		52.8	39.8
Other Current Liabilities - Accrued Short-term Benefit Liability		0.0	0.0
Employee Benefits and Pension Obligations - Accrued Long-term Benefit Liability		0.0	0.0
Funded (Underfunded) Status		52.8	39.8
Components
Net Actuarial Loss		11.5	21.1
Prior Service Cost (Credit)		(17.2)	(21.6)
Components of Change in Amounts Included in AOCI and Regulatory Assets
Actuarial (Gain) Loss During the Year		(9.2)	(11.4)
Amortization of Actuarial Gain (Loss)		(0.4)	(1.4)
Prior Service (Credit) Cost		(0.8)	(0.6)
Amortization of Prior Service Credit (Cost)		5.2	5.2
Change for the Year		(5.2)	(8.2)
Benefit Plans (Textuals) [Abstract]
Company Contributions		0.0	0.0
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Regulatory Assets [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(3.0)	0.0
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Deferred Income Taxes [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		(0.5)	0.0
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Net of Tax AOCI [Member]
Recorded as
Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets		$ (2.2)	$ (0.5)

[1] Rates are for base pay only.  In addition, an amount is added to reflect target incentive compensation for exempt employees and overtime and incentive pay for nonexempt employees.

[2] Rates are for base pay only.  In addition, an amount is added to reflect target incentive compensation for exempt employees and overtime and incentive pay for nonexempt employees.

[3] Contributions to the qualified pension plan were $110 million and $0 for the years ended December 31, 2020 and 2019, respectively. Contributions to the non-qualified pension plans were $6 million and $6 million for the years ended December 31, 2020 and 2019, respectively.