Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		$ 4,038.9
Total Revenues		4,048.3	$ 3,933.3
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		1,517.6
Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		748.7
2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		256.1
4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		164.1
After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations		348.7
Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3,070.6
Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1,569.1
Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		816.1
Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		632.1
Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		53.3
Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		877.6
Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		359.1
Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		208.8
Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		309.7
Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		90.7
Total Revenues		28.5
Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Total Revenues		0.0
Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		9.4
Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(19.1)
AEP Texas Inc. [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		354.1
Total Revenues		371.6	343.6
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	233.4
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		9.0		$ 12.3
AEP Texas Inc. [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		0.0		0.0
AEP Texas Inc. [Member] | Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	233.4
AEP Texas Inc. [Member] | 2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
AEP Texas Inc. [Member] | 4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
AEP Texas Inc. [Member] | After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
AEP Texas Inc. [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		269.0
AEP Texas Inc. [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		131.6
AEP Texas Inc. [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		105.4
AEP Texas Inc. [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		25.8
AEP Texas Inc. [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		6.2
AEP Texas Inc. [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		78.0
AEP Texas Inc. [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Texas Inc. [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Texas Inc. [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		78.0
AEP Texas Inc. [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Texas Inc. [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		6.7
Total Revenues		0.0
AEP Texas Inc. [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.4
Total Revenues		17.8
AEP Texas Inc. [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		17.5
AEP Texas Inc. [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(0.3)
AEP Transmission Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		210.5
Total Revenues		193.5	152.7
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	536.2
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		102.0		93.2
AEP Transmission Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		60.6		47.1
AEP Transmission Co [Member] | Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	536.2
AEP Transmission Co [Member] | 2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
AEP Transmission Co [Member] | 4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
AEP Transmission Co [Member] | After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
AEP Transmission Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		208.4
AEP Transmission Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		48.3
AEP Transmission Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		160.1
AEP Transmission Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.1
Total Revenues		0.0
AEP Transmission Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2.0
Total Revenues		0.0
AEP Transmission Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(17.0)
AEP Transmission Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(17.0)
Appalachian Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		826.3
Total Revenues		820.4	792.8
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	157.9
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		67.6		69.3
Appalachian Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		36.3		35.6
Appalachian Power Co [Member] | Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	92.0
Appalachian Power Co [Member] | 2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	31.8
Appalachian Power Co [Member] | 4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	22.7
Appalachian Power Co [Member] | After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	11.4
Appalachian Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		727.5
Appalachian Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		414.0
Appalachian Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		147.1
Appalachian Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		146.8
Appalachian Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		19.6
Appalachian Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		87.6
Appalachian Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		22.3
Appalachian Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		40.5
Appalachian Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		16.9
Appalachian Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		7.9
Appalachian Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		10.2
Total Revenues		0.0
Appalachian Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.0
Total Revenues		0.0
Appalachian Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(5.9)
Appalachian Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(5.9)
Indiana Michigan Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		576.3
Total Revenues		576.8	560.5
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	42.3
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		49.9		50.0
Indiana Michigan Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		14.8		15.1
Indiana Michigan Power Co [Member] | Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	20.6
Indiana Michigan Power Co [Member] | 2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	8.7
Indiana Michigan Power Co [Member] | 4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	8.7
Indiana Michigan Power Co [Member] | After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	4.3
Indiana Michigan Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		432.8
Indiana Michigan Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		189.0
Indiana Michigan Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		110.8
Indiana Michigan Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		130.8
Indiana Michigan Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2.2
Indiana Michigan Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		120.8
Indiana Michigan Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		111.1
Indiana Michigan Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2.9
Indiana Michigan Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		6.8
Indiana Michigan Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Indiana Michigan Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		7.7
Total Revenues		5.5
Indiana Michigan Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		15.0
Total Revenues		0.0
Indiana Michigan Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.5
Indiana Michigan Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(5.0)
Ohio Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		780.7
Total Revenues		790.9	746.1
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	42.1
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		60.4		70.2
Ohio Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		27.1		26.1
Ohio Power Co [Member] | Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	42.1
Ohio Power Co [Member] | 2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Ohio Power Co [Member] | 4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Ohio Power Co [Member] | After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Ohio Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		722.4
Ohio Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		436.8
Ohio Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		194.7
Ohio Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		87.7
Ohio Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3.2
Ohio Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		16.0
Ohio Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Ohio Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Ohio Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		16.0
Ohio Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Ohio Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		42.3
Total Revenues		0.8
Ohio Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Total Revenues		3.1
Ohio Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		10.2
Ohio Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		6.3
Public Service Co Of Oklahoma [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		333.5
Total Revenues		336.8	304.1
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	11.9
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		27.7		32.9
Public Service Co Of Oklahoma [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		6.2		6.1
Public Service Co Of Oklahoma [Member] | Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	11.9
Public Service Co Of Oklahoma [Member] | 2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Public Service Co Of Oklahoma [Member] | 4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Public Service Co Of Oklahoma [Member] | After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Public Service Co Of Oklahoma [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		312.8
Public Service Co Of Oklahoma [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		141.1
Public Service Co Of Oklahoma [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		88.0
Public Service Co Of Oklahoma [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		65.4
Public Service Co Of Oklahoma [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		18.3
Public Service Co Of Oklahoma [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		16.5
Public Service Co Of Oklahoma [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		5.9
Public Service Co Of Oklahoma [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Public Service Co Of Oklahoma [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		10.6
Public Service Co Of Oklahoma [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Public Service Co Of Oklahoma [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3.1
Total Revenues		0.0
Public Service Co Of Oklahoma [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.1
Total Revenues		0.0
Public Service Co Of Oklahoma [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		3.3
Public Service Co Of Oklahoma [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		3.3
Southwestern Electric Power Co [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		419.7
Total Revenues		419.4	401.3
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	24.9
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		18.0		30.2
Southwestern Electric Power Co [Member] | Short-term Contract with Customer [Member]
Assets, Current [Abstract]
Affiliated Companies - Contracts with Customers		11.4		$ 11.0
Southwestern Electric Power Co [Member] | Less Than 1 Year [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	24.9
Southwestern Electric Power Co [Member] | 2-3 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Southwestern Electric Power Co [Member] | 4-5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Southwestern Electric Power Co [Member] | After 5 Years [Member]
Revenue, Performance Obligation [Abstract]
Fixed Performance Obligations	[1]	0.0
Southwestern Electric Power Co [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		327.7
Southwestern Electric Power Co [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		140.1
Southwestern Electric Power Co [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		110.1
Southwestern Electric Power Co [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		75.4
Southwestern Electric Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2.1
Southwestern Electric Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		85.9
Southwestern Electric Power Co [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		59.9
Southwestern Electric Power Co [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Southwestern Electric Power Co [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		20.2
Southwestern Electric Power Co [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		5.8
Southwestern Electric Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		5.8
Total Revenues		0.0
Southwestern Electric Power Co [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.3
Total Revenues		0.0
Southwestern Electric Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(0.3)
Southwestern Electric Power Co [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(0.3)
Consolidation Eliminations [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(235.0)
Total Revenues		(256.7)	(217.5)
Consolidation Eliminations [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(209.9)
Consolidation Eliminations [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(30.1)
Consolidation Eliminations [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(179.8)
Consolidation Eliminations [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Consolidation Eliminations [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Total Revenues		0.0
Consolidation Eliminations [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		(25.1)
Total Revenues		(21.7)
Consolidation Eliminations [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(21.7)
Consolidation Eliminations [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.0
Consolidation Eliminations [Member] | AEP Transmission Co [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.0	0.0
Vertically Integrated Utilities [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2,411.6
Total Revenues		2,408.0	2,290.4
Vertically Integrated Utilities [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		2,079.7
Vertically Integrated Utilities [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1,001.2
Vertically Integrated Utilities [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		515.8
Vertically Integrated Utilities [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		518.9
Vertically Integrated Utilities [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		43.8
Vertically Integrated Utilities [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		292.0
Vertically Integrated Utilities [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		214.0
Vertically Integrated Utilities [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		3.0
Vertically Integrated Utilities [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		57.9
Vertically Integrated Utilities [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		17.1
Vertically Integrated Utilities [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		34.7
Total Revenues		5.5
Vertically Integrated Utilities [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		5.2
Total Revenues		0.0
Vertically Integrated Utilities [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(3.6)
Vertically Integrated Utilities [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(9.1)
Transmission And Distribution Companies [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1,134.7
Total Revenues		1,162.4	1,086.4
Transmission And Distribution Companies [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		990.9
Transmission And Distribution Companies [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		567.9
Transmission And Distribution Companies [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		300.3
Transmission And Distribution Companies [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		113.2
Transmission And Distribution Companies [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		9.5
Transmission And Distribution Companies [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		94.1
Transmission And Distribution Companies [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Transmission And Distribution Companies [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Transmission And Distribution Companies [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		94.1
Transmission And Distribution Companies [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Transmission And Distribution Companies [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Transmission And Distribution Companies [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		49.0
Total Revenues		0.0
Transmission And Distribution Companies [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.7
Total Revenues		21.7
Transmission And Distribution Companies [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		27.7
Transmission And Distribution Companies [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		6.0
AEP Transmission Holdco [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		221.5
Total Revenues		205.5	156.1
AEP Transmission Holdco [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		219.5
AEP Transmission Holdco [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		56.8
AEP Transmission Holdco [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		162.7
AEP Transmission Holdco [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
AEP Transmission Holdco [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.3
Total Revenues		0.0
AEP Transmission Holdco [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.7
Total Revenues		0.0
AEP Transmission Holdco [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(16.0)
AEP Transmission Holdco [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		(16.0)
Generation And Marketing [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		484.1
Total Revenues		505.1	591.4
Generation And Marketing [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Generation And Marketing [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Generation And Marketing [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Generation And Marketing [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Generation And Marketing [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Generation And Marketing [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		481.9
Generation And Marketing [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		145.1
Generation And Marketing [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		27.1
Generation And Marketing [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Generation And Marketing [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Generation And Marketing [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		309.7
Generation And Marketing [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		1.7
Total Revenues		21.0
Generation And Marketing [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.5
Total Revenues		0.0
Generation And Marketing [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		21.0
Generation And Marketing [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		0.0
Corporate and Other [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		22.0
Total Revenues	[2]	24.0	$ 26.5
Corporate and Other [Member] | Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Residential [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Other Retail [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Generation [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Generation - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Transmission [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Transmission - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		0.0
Corporate and Other [Member] | Other Revenues [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		5.0
Total Revenues		2.0
Corporate and Other [Member] | Other Revenues - Affiliated [Member]
Disaggregation of Revenue [Abstract]
Revenue from Contracts with Customers		17.0
Total Revenues		0.0
Corporate and Other [Member] | Alternative and Other [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		2.0
Corporate and Other [Member] | Alternative [Member]
Disaggregation of Revenue [Abstract]
Total Revenues		$ 0.0

[1] Amounts include affiliated and nonaffiliated revenues except for AEP.

[2] 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.