Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		$ 4,057.4		$ 8,096.3
Total Revenues		4,013.2	$ 3,576.5	8,061.5	$ 7,509.8
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		1,290.0		1,290.0
2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		503.6		503.6
2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		271.0		271.0
2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		166.7		166.7
2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		348.7		348.7
Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3,022.1		6,092.7
Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1,387.9		2,957.0
Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		885.2		1,701.3
Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		692.8		1,324.9
Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		56.2		109.5
Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		941.0		1,818.6
Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		344.8		703.9
Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		264.8		473.6
Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		331.4		641.1
Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		94.3		185.0
Total Revenues		(8.6)		19.9
Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Total Revenues		0.0		0.0
Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(44.2)		(34.8)
Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(35.6)		(54.7)
AEP Texas Inc. [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		370.9		725.0
Total Revenues		388.3	389.5	759.9	733.1
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		155.6		155.6
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		42.7		42.7		$ 12.3
AEP Texas Inc. [Member] | 2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		155.6		155.6
AEP Texas Inc. [Member] | 2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
AEP Texas Inc. [Member] | 2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
AEP Texas Inc. [Member] | 2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
AEP Texas Inc. [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		285.7		554.7
AEP Texas Inc. [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		143.2		274.8
AEP Texas Inc. [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		109.4		214.8
AEP Texas Inc. [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		26.7		52.5
AEP Texas Inc. [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		6.4		12.6
AEP Texas Inc. [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		78.0		156.0
AEP Texas Inc. [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Texas Inc. [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Texas Inc. [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		78.0		156.0
AEP Texas Inc. [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Texas Inc. [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		6.8		13.5
Total Revenues		0.0		0.0
AEP Texas Inc. [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.4		0.8
Total Revenues		17.2		35.0
AEP Texas Inc. [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		17.4		34.9
AEP Texas Inc. [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.2		(0.1)
AEP Transmission Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		189.8		400.3
Total Revenues		183.8	229.4	377.3	382.1
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		332.1		332.1
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		88.8		88.8		93.2
AEP Transmission Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		87.8		87.8		47.1
AEP Transmission Co [Member] | 2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		332.1		332.1
AEP Transmission Co [Member] | 2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
AEP Transmission Co [Member] | 2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
AEP Transmission Co [Member] | 2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
AEP Transmission Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		183.4		391.8
AEP Transmission Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		52.6		100.9
AEP Transmission Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		130.8		290.9
AEP Transmission Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		4.6		4.7
Total Revenues		0.0		0.0
AEP Transmission Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.8		3.8
Total Revenues		0.0		0.0
AEP Transmission Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(6.0)		(23.0)
AEP Transmission Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(6.0)		(23.0)
Appalachian Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		680.6		1,506.9
Total Revenues		667.0	675.3	1,487.4	1,468.1
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		130.2		130.2
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		80.1		80.1		69.3
Appalachian Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		47.1		47.1		35.6
Appalachian Power Co [Member] | 2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		61.3		61.3
Appalachian Power Co [Member] | 2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		32.5		32.5
Appalachian Power Co [Member] | 2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		25.0		25.0
Appalachian Power Co [Member] | 2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		11.4		11.4
Appalachian Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		594.2		1,321.7
Appalachian Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		282.3		696.3
Appalachian Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		141.1		288.2
Appalachian Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		152.0		298.8
Appalachian Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		18.8		38.4
Appalachian Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		71.3		158.9
Appalachian Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		28.1		50.4
Appalachian Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		28.7		69.2
Appalachian Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		11.4		28.3
Appalachian Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3.1		11.0
Appalachian Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.5		10.7
Total Revenues		0.0		0.0
Appalachian Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		14.6		15.6
Total Revenues		0.0		0.0
Appalachian Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(13.6)		(19.5)
Appalachian Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(13.6)		(19.5)
Indiana Michigan Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		604.4		1,180.7
Total Revenues		589.7	467.3	1,166.5	1,027.8
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		35.8		35.8
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		63.1		63.1		50.0
Indiana Michigan Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		25.7		25.7		15.1
Indiana Michigan Power Co [Member] | 2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		14.0		14.0
Indiana Michigan Power Co [Member] | 2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		8.8		8.8
Indiana Michigan Power Co [Member] | 2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		8.7		8.7
Indiana Michigan Power Co [Member] | 2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		4.3		4.3
Indiana Michigan Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		432.5		865.3
Indiana Michigan Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		163.0		352.0
Indiana Michigan Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		123.4		234.2
Indiana Michigan Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		144.6		275.4
Indiana Michigan Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.5		3.7
Indiana Michigan Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		146.0		266.8
Indiana Michigan Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		141.0		252.1
Indiana Michigan Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.1		4.0
Indiana Michigan Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3.9		10.7
Indiana Michigan Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Indiana Michigan Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(0.2)		7.5
Total Revenues		(14.2)		(8.7)
Indiana Michigan Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		26.1		41.1
Total Revenues		0.0		0.0
Indiana Michigan Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(14.7)		(14.2)
Indiana Michigan Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(0.5)		(5.5)
Ohio Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		761.3		1,542.0
Total Revenues		748.8	663.9	1,539.7	1,410.0
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		55.4		55.4
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		75.8		75.8		70.2
Ohio Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		42.3		42.3		26.1
Ohio Power Co [Member] | 2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		43.0		43.0
Ohio Power Co [Member] | 2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		12.4		12.4
Ohio Power Co [Member] | 2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Ohio Power Co [Member] | 2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Ohio Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		710.4		1,432.8
Ohio Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		388.1		824.9
Ohio Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		215.2		409.9
Ohio Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		103.8		191.5
Ohio Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3.3		6.5
Ohio Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		12.0		28.0
Ohio Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Ohio Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Ohio Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		12.0		28.0
Ohio Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Ohio Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		32.3		74.6
Total Revenues		(0.8)		0.0
Ohio Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		6.6		6.6
Total Revenues		4.9		8.0
Ohio Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(12.5)		(2.3)
Ohio Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(16.6)		(10.3)
Public Service Co Of Oklahoma [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		392.7		726.2
Total Revenues		398.3	344.7	735.1	648.8
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		8.2		8.2
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		42.9		42.9		32.9
Public Service Co Of Oklahoma [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		12.1		12.1		6.1
Public Service Co Of Oklahoma [Member] | 2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		8.2		8.2
Public Service Co Of Oklahoma [Member] | 2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Public Service Co Of Oklahoma [Member] | 2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Public Service Co Of Oklahoma [Member] | 2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Public Service Co Of Oklahoma [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		374.2		687.0
Public Service Co Of Oklahoma [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		169.5		310.6
Public Service Co Of Oklahoma [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		107.7		195.7
Public Service Co Of Oklahoma [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		74.8		140.2
Public Service Co Of Oklahoma [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		22.2		40.5
Public Service Co Of Oklahoma [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		13.6		30.1
Public Service Co Of Oklahoma [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		8.3		14.2
Public Service Co Of Oklahoma [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Public Service Co Of Oklahoma [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		4.9		15.5
Public Service Co Of Oklahoma [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.4		0.4
Public Service Co Of Oklahoma [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3.8		6.9
Total Revenues		0.0		0.0
Public Service Co Of Oklahoma [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.1		2.2
Total Revenues		0.0		0.0
Public Service Co Of Oklahoma [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		5.6		8.9
Public Service Co Of Oklahoma [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		5.6		8.9
Southwestern Electric Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		454.2		873.9
Total Revenues		457.1	424.7	876.5	826.0
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		16.7		16.7
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		38.3		38.3		30.2
Southwestern Electric Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		16.4		16.4		$ 11.0
Southwestern Electric Power Co [Member] | 2018 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		16.7		16.7
Southwestern Electric Power Co [Member] | 2019-2020 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Southwestern Electric Power Co [Member] | 2021-2022 [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Southwestern Electric Power Co [Member] | 2022 and Forward [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		0.0		0.0
Southwestern Electric Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		371.4		699.1
Southwestern Electric Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		158.2		298.3
Southwestern Electric Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		125.9		236.0
Southwestern Electric Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		85.2		160.6
Southwestern Electric Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2.1		4.2
Southwestern Electric Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		77.5		163.4
Southwestern Electric Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		55.7		115.6
Southwestern Electric Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Southwestern Electric Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		16.8		37.0
Southwestern Electric Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		5.0		10.8
Southwestern Electric Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		4.9		10.7
Total Revenues		0.0		0.0
Southwestern Electric Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.4		0.7
Total Revenues		0.0		0.0
Southwestern Electric Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		2.9		2.6
Southwestern Electric Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		2.9		2.6
Consolidation Eliminations [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(148.5)		(383.5)
Total Revenues		(169.8)	(284.3)	(426.5)	(501.8)
Consolidation Eliminations [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(125.9)		(335.8)
Consolidation Eliminations [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(26.6)		(56.7)
Consolidation Eliminations [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(99.3)		(279.1)
Consolidation Eliminations [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Total Revenues		0.0		0.0
Consolidation Eliminations [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(22.6)		(47.7)
Total Revenues		(21.3)		(43.0)
Consolidation Eliminations [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(21.3)		(43.0)
Consolidation Eliminations [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.0		0.0
Consolidation Eliminations [Member] | AEP Transmission Co [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.0	(0.1)	0.0	(0.1)
Vertically Integrated Utilities [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2,373.5		4,785.1
Total Revenues		2,349.0	2,120.5	4,757.0	4,410.9
Vertically Integrated Utilities [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2,026.0		4,105.7
Vertically Integrated Utilities [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		857.0		1,858.2
Vertically Integrated Utilities [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		559.6		1,075.4
Vertically Integrated Utilities [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		563.1		1,082.0
Vertically Integrated Utilities [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		46.3		90.1
Vertically Integrated Utilities [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		305.9		597.9
Vertically Integrated Utilities [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		243.7		457.7
Vertically Integrated Utilities [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.6		4.6
Vertically Integrated Utilities [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		48.7		106.6
Vertically Integrated Utilities [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		11.9		29.0
Vertically Integrated Utilities [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		15.5		50.2
Total Revenues		(14.2)		(8.7)
Vertically Integrated Utilities [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		26.1		31.3
Total Revenues		0.0		0.0
Vertically Integrated Utilities [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(24.5)		(28.1)
Vertically Integrated Utilities [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(10.3)		(19.4)
Transmission And Distribution Utilities [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1,132.1		2,266.8
Total Revenues		1,137.0	1,053.5	2,299.4	2,139.9
Transmission And Distribution Utilities [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		996.1		1,987.0
Transmission And Distribution Utilities [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		530.9		1,098.8
Transmission And Distribution Utilities [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		325.6		625.9
Transmission And Distribution Utilities [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		129.7		242.9
Transmission And Distribution Utilities [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		9.9		19.4
Transmission And Distribution Utilities [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		90.5		184.6
Transmission And Distribution Utilities [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Transmission And Distribution Utilities [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Transmission And Distribution Utilities [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		90.5		184.6
Transmission And Distribution Utilities [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Transmission And Distribution Utilities [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Transmission And Distribution Utilities [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		38.5		87.5
Total Revenues		0.0		0.0
Transmission And Distribution Utilities [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		7.0		7.7
Total Revenues		21.3		43.0
Transmission And Distribution Utilities [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		4.9		32.6
Transmission And Distribution Utilities [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(16.4)		(10.4)
AEP Transmission Holdco [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		221.4		442.9
Total Revenues		212.5		418.0
AEP Transmission Holdco [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		213.0		432.5
AEP Transmission Holdco [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		78.8		135.6
AEP Transmission Holdco [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		134.2		296.9
AEP Transmission Holdco [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		6.3		6.6
Total Revenues		0.0		0.0
AEP Transmission Holdco [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2.1		3.8
Total Revenues		0.0		0.0
AEP Transmission Holdco [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(8.9)		(24.9)
AEP Transmission Holdco [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(8.9)		(24.9)
Generation And Marketing [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		457.6		941.7
Total Revenues		460.7	410.6	965.8	1,002.0
Generation And Marketing [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		457.5		939.4
Generation And Marketing [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		101.1		246.2
Generation And Marketing [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		25.0		52.1
Generation And Marketing [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		331.4		641.1
Generation And Marketing [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.6		2.3
Total Revenues		3.1		24.1
Generation And Marketing [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(0.5)		0.0
Total Revenues		0.0		0.0
Generation And Marketing [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		3.1		24.1
Generation And Marketing [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.0		0.0
Other Segments [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		21.3		43.3
Total Revenues	[1]	23.8	$ 28.9	47.8	$ 55.4
Other Segments [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		46.8		46.8
Other Segments [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(46.8)		(46.8)
Other Segments [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0		0.0
Other Segments [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		33.4		38.4
Total Revenues		2.5		4.5
Other Segments [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(12.1)		4.9
Total Revenues		0.0		0.0
Other Segments [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		2.5		4.5
Other Segments [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		$ 0.0		$ 0.0

[1] Corporate and Other primarily includes the purchasing of receivables from certain AEP utility subsidiaries. This segment also includes Parent’s guarantee revenue received from affiliates, investment income, interest income and interest expense and other nonallocated costs.