Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019		Mar. 31, 2018		Dec. 31, 2018
Disaggregation of Revenue
Revenue from Contracts with Customers		$ 4,056.8		$ 4,048.3
Total Revenues		4,056.8		4,048.3
Revenue, Performance Obligation
Fixed Performance Obligations		1,379.8
Revenue Textuals
Revenue from Related Parties		0.0		0.0
2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		732.3
2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		199.1
2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		162.7
After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		285.7
Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3,102.8		3,070.6	[1]
Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,568.5		1,569.1
Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		822.1		802.1
Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		657.8		645.1
Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		54.4		54.3
Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		825.3		877.6
Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		255.0	[2]	359.1	[3]
Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		208.8		208.8	[4]
Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		361.5	[5]	309.7
Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		78.1	[6]	90.7	[7]
Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		4,006.2		4,038.9
Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		50.6		9.4
Alternative [Member]
Disaggregation of Revenue
Total Revenues		(0.2)	[6]	(19.1)	[7]
Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		65.0		48.1
Total Revenues		50.8	[6]	28.5	[7]
AEP Texas Inc. [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		351.8		354.1
Total Revenues		390.7		371.6
Revenue, Performance Obligation
Fixed Performance Obligations		278.2
Current Assets
Affiliated Companies - Contracts with Customers		15.9				$ 15.0
Revenue Textuals
Revenue from Related Parties		40.2		18.2
AEP Texas Inc. [Member] | 2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		278.2
AEP Texas Inc. [Member] | 2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Texas Inc. [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Texas Inc. [Member] | After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Texas Inc. [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		259.1		269.0	[8]
AEP Texas Inc. [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		120.9		131.6
AEP Texas Inc. [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		97.9		99.4
AEP Texas Inc. [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		33.0		30.9
AEP Texas Inc. [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		7.3		7.1
AEP Texas Inc. [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		85.8		78.0
AEP Texas Inc. [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[9]	0.0	[10]
AEP Texas Inc. [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		85.8	[11]	78.0	[12]
AEP Texas Inc. [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		6.9	[13]	7.1	[14]
AEP Texas Inc. [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		38.9		17.5
AEP Texas Inc. [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		(0.9)	[15]	(0.3)	[16]
AEP Texas Inc. [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.7		1.0
Total Revenues		39.8	[15]	17.8	[16]
AEP Transmission Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		245.2		187.0	[17]
Total Revenues		243.5		191.7	[17],[18]
Revenue, Performance Obligation
Fixed Performance Obligations		672.5
Current Assets
Affiliated Companies - Contracts with Customers		68.8				61.0
Revenue Textuals
Revenue from Related Parties		193.2		160.7	[18]
AEP Transmission Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		65.9				58.6
AEP Transmission Co [Member] | 2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		672.5
AEP Transmission Co [Member] | 2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Transmission Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Transmission Co [Member] | After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Transmission Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[8],[17]
AEP Transmission Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[17]
AEP Transmission Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[17]
AEP Transmission Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[17]
AEP Transmission Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[17]
AEP Transmission Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		242.1		185.0	[17]
AEP Transmission Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[9]	0.0	[10],[17]
AEP Transmission Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		242.1	[11]	185.0	[12],[17]
Revenue Textuals
Revenue from Related Parties		195.0		160.0
AEP Transmission Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3.1	[13]	2.0	[14],[17]
AEP Transmission Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		(1.7)		4.7	[17]
AEP Transmission Co [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		(1.7)	[15]	4.7	[16],[17]
AEP Transmission Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.1	[18]
Total Revenues		0.0	[15]	0.0	[16],[17]
Appalachian Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		788.4		826.3
Total Revenues		792.8		820.4
Revenue, Performance Obligation
Fixed Performance Obligations		174.8
Current Assets
Affiliated Companies - Contracts with Customers		60.3				73.4
Revenue Textuals
Revenue from Related Parties		51.7		49.4
Appalachian Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		46.3				52.5
Appalachian Power Co [Member] | 2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		108.9
Appalachian Power Co [Member] | 2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		31.1
Appalachian Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		23.2
Appalachian Power Co [Member] | After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		11.6
Appalachian Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		681.8		727.5	[8]
Appalachian Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		372.5		414.0
Appalachian Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		142.2		146.6
Appalachian Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		147.5		147.3
Appalachian Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		19.6		19.6
Appalachian Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		93.2		87.6
Appalachian Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		67.5	[9]	62.8	[10]
Revenue Textuals
Revenue from Related Parties		35.0		40.0
Appalachian Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		25.7	[11]	24.8	[12]
Appalachian Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		13.4	[13]	11.2	[14]
Appalachian Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		4.4		(5.9)
Appalachian Power Co [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		4.4	[15]	(5.9)	[16]
Appalachian Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.4		3.5
Total Revenues		0.0	[15]	0.0	[16]
Indiana Michigan Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		619.1		576.3
Total Revenues		614.3		576.8
Revenue, Performance Obligation
Fixed Performance Obligations		43.5
Current Assets
Affiliated Companies - Contracts with Customers		55.4				75.0
Revenue Textuals
Revenue from Related Parties		2.3		4.7
Indiana Michigan Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		24.0				35.3
Indiana Michigan Power Co [Member] | 2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		21.5
Indiana Michigan Power Co [Member] | 2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		8.8
Indiana Michigan Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		8.8
Indiana Michigan Power Co [Member] | After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		4.4
Indiana Michigan Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		479.9		432.8	[8]
Indiana Michigan Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		218.4		189.0
Indiana Michigan Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		121.3		109.6
Indiana Michigan Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		138.4		132.0
Indiana Michigan Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1.8		2.2
Indiana Michigan Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		118.2		120.8
Indiana Michigan Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		111.9	[9]	114.0	[10]
Indiana Michigan Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		6.3	[11]	6.8	[12]
Indiana Michigan Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		21.0	[13]	22.7	[14]
Indiana Michigan Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		(4.8)		0.5
Indiana Michigan Power Co [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		(4.8)	[15]	(5.0)	[16]
Indiana Michigan Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.0		5.0
Total Revenues		0.0	[15]	5.5	[16]
Revenue Textuals
Revenue from Related Parties		15.0		15.0
Ohio Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		828.1		780.7
Total Revenues		836.8		790.9
Revenue, Performance Obligation
Fixed Performance Obligations		47.4
Current Assets
Affiliated Companies - Contracts with Customers		55.9				70.8
Revenue Textuals
Revenue from Related Parties		7.5		3.1
Ohio Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		31.2				46.1
Ohio Power Co [Member] | 2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		47.4
Ohio Power Co [Member] | 2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Ohio Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Ohio Power Co [Member] | After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Ohio Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		775.2		722.4	[8]
Ohio Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		471.6		436.8
Ohio Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		210.5		194.5
Ohio Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		89.7		87.9
Ohio Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3.4		3.2
Ohio Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		13.9		16.0
Ohio Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[9]	0.0	[10]
Ohio Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		13.9	[11]	16.0	[12]
Ohio Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		39.0	[13]	42.3	[14]
Ohio Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		8.7		10.2
Ohio Power Co [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		3.6	[15]	6.3	[16]
Ohio Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.8		1.5
Total Revenues		5.1	[15]	3.9	[16]
Public Service Co Of Oklahoma [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		334.0		333.5
Total Revenues		332.8		336.8
Revenue, Performance Obligation
Fixed Performance Obligations		13.6
Current Assets
Affiliated Companies - Contracts with Customers		24.3				26.2
Revenue Textuals
Revenue from Related Parties		1.6		1.1
Public Service Co Of Oklahoma [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		13.3				12.4
Public Service Co Of Oklahoma [Member] | 2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		13.6
Public Service Co Of Oklahoma [Member] | 2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Public Service Co Of Oklahoma [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Public Service Co Of Oklahoma [Member] | After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Public Service Co Of Oklahoma [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		309.8		312.8	[8]
Public Service Co Of Oklahoma [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		140.0		141.1
Public Service Co Of Oklahoma [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		80.8		84.3
Public Service Co Of Oklahoma [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		71.0		69.1
Public Service Co Of Oklahoma [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		18.0		18.3
Public Service Co Of Oklahoma [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		18.4		16.5
Public Service Co Of Oklahoma [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		8.6	[9]	5.9	[10]
Public Service Co Of Oklahoma [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		9.8	[11]	10.6	[12]
Public Service Co Of Oklahoma [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		5.8	[13]	4.2	[14]
Public Service Co Of Oklahoma [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		(1.2)		3.3
Public Service Co Of Oklahoma [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		(1.2)	[15]	3.3	[16]
Public Service Co Of Oklahoma [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.0		0.6
Total Revenues		0.0	[15]	0.0	[16]
Southwestern Electric Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		426.4		419.7
Total Revenues		421.1		419.4
Revenue, Performance Obligation
Fixed Performance Obligations		28.7
Current Assets
Affiliated Companies - Contracts with Customers		20.0				28.8
Revenue Textuals
Revenue from Related Parties		6.4		6.1
Southwestern Electric Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		10.6				$ 16.3
Southwestern Electric Power Co [Member] | 2019 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		28.7
Southwestern Electric Power Co [Member] | 2020-2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Southwestern Electric Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Southwestern Electric Power Co [Member] | After 2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Southwestern Electric Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		337.2		327.7	[8]
Southwestern Electric Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		140.1		140.1
Southwestern Electric Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		113.7		108.3
Southwestern Electric Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		81.2		77.2
Southwestern Electric Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.2		2.1
Southwestern Electric Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		81.4		85.9
Southwestern Electric Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		57.2	[9]	59.9	[10]
Southwestern Electric Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		24.2	[11]	26.0	[12]
Southwestern Electric Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		7.8	[13]	6.1	[14]
Southwestern Electric Power Co [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		(5.3)		(0.3)
Southwestern Electric Power Co [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		(5.3)	[15]	(0.3)	[16]
Southwestern Electric Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.4		0.3
Total Revenues		0.0	[15]	0.0	[16]
Consolidation Eliminations [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Total Revenues		(332.2)		(256.7)
Revenue Textuals
Revenue from Related Parties		(332.2)		(256.7)
Consolidation Eliminations [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1.8		0.0	[1]
Consolidation Eliminations [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1.8		0.0
Consolidation Eliminations [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(297.9)		(209.9)
Consolidation Eliminations [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(78.5)	[2]	(30.1)	[3]
Consolidation Eliminations [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(219.4)	[5]	(179.8)	[4]
Consolidation Eliminations [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Consolidation Eliminations [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(36.1)	[6]	(25.1)	[7]
Consolidation Eliminations [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(332.2)		(235.0)
Consolidation Eliminations [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		0.0		(21.7)
Consolidation Eliminations [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		0.0	[6]	0.0	[7]
Consolidation Eliminations [Member] | Other Revenues [Member]
Disaggregation of Revenue
Total Revenues		0.0	[6]	(21.7)	[7]
Consolidation Eliminations [Member] | AEP Transmission Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Total Revenues		0.0		0.0
Revenue Textuals
Revenue from Related Parties		0.0		0.0
Vertically Integrated Utilities [Member]
Disaggregation of Revenue
Total Revenues		2,403.3		2,408.0
Revenue Textuals
Revenue from Related Parties		31.0		26.5
Vertically Integrated Utilities [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,069.0		2,079.7	[1]
Vertically Integrated Utilities [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		982.4		1,001.2
Vertically Integrated Utilities [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		511.2		508.0
Vertically Integrated Utilities [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		532.1		526.6
Vertically Integrated Utilities [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		43.3		43.9
Vertically Integrated Utilities [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		298.2		292.0
Vertically Integrated Utilities [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		224.7	[2]	217.0	[3]
Vertically Integrated Utilities [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		73.5	[5]	75.0	[4]
Vertically Integrated Utilities [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		39.5	[6]	39.9	[7]
Vertically Integrated Utilities [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,406.7		2,411.6
Vertically Integrated Utilities [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		(3.4)		(3.6)
Vertically Integrated Utilities [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		(3.4)	[6]	(9.1)	[7]
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Disaggregation of Revenue
Total Revenues		0.0	[6]	5.5	[7]
Transmission And Distribution Companies [Member]
Disaggregation of Revenue
Total Revenues		1,222.0		1,162.4
Revenue Textuals
Revenue from Related Parties		42.2		21.2
Transmission And Distribution Companies [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,032.0		990.9	[1]
Transmission And Distribution Companies [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		586.1		567.9
Transmission And Distribution Companies [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		310.9		294.1
Transmission And Distribution Companies [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		123.9		118.5
Transmission And Distribution Companies [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		11.1		10.4
Transmission And Distribution Companies [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		99.6		94.1
Transmission And Distribution Companies [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[2]	0.0	[3]
Transmission And Distribution Companies [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		99.6	[5]	94.1	[4]
Transmission And Distribution Companies [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Transmission And Distribution Companies [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		46.0	[6]	49.7	[7]
Transmission And Distribution Companies [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,177.6		1,134.7
Transmission And Distribution Companies [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		44.4		27.7
Transmission And Distribution Companies [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		5.0	[6]	6.0	[7]
Transmission And Distribution Companies [Member] | Other Revenues [Member]
Disaggregation of Revenue
Total Revenues		39.4	[6]	21.7	[7]
AEP Transmission Holdco [Member]
Disaggregation of Revenue
Total Revenues		256.4		205.5
AEP Transmission Holdco [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[1]
AEP Transmission Holdco [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		255.1		219.5
AEP Transmission Holdco [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[2]	0.0	[3]
AEP Transmission Holdco [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		255.1	[5]	219.5	[4]
Revenue Textuals
Revenue from Related Parties		198.0		162.0
AEP Transmission Holdco [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
AEP Transmission Holdco [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3.1	[6]	2.0	[7]
AEP Transmission Holdco [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		258.2		221.5
AEP Transmission Holdco [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		(1.8)		(16.0)
AEP Transmission Holdco [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		(1.8)	[6]	(16.0)	[7]
AEP Transmission Holdco [Member] | Other Revenues [Member]
Disaggregation of Revenue
Total Revenues		0.0	[6]	0.0	[7]
Generation And Marketing [Member]
Disaggregation of Revenue
Total Revenues		481.8		505.1
Revenue Textuals
Revenue from Related Parties		42.1		27.6
Generation And Marketing [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[1]
Generation And Marketing [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Generation And Marketing [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		470.3		481.9
Generation And Marketing [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		108.8	[2]	172.2	[3]
Revenue Textuals
Revenue from Related Parties		37.0		27.0
Generation And Marketing [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[5]	0.0	[4]
Generation And Marketing [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		361.5		309.7
Generation And Marketing [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.3	[6]	2.2	[7]
Generation And Marketing [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		472.6		484.1
Generation And Marketing [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		9.2		21.0
Generation And Marketing [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		0.0	[6]	0.0	[7]
Generation And Marketing [Member] | Other Revenues [Member]
Disaggregation of Revenue
Total Revenues		9.2	[6]	21.0	[7]
Corporate and Other [Member]
Disaggregation of Revenue
Total Revenues	[19]	25.5		24.0
Revenue Textuals
Revenue from Related Parties	[19]	21.7		17.0
Corporate and Other [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0	[1]
Corporate and Other [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Corporate and Other [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Corporate and Other [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Corporate and Other [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Corporate and Other [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Corporate and Other [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[2]	0.0	[3]
Corporate and Other [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[5]	0.0	[4]
Corporate and Other [Member] | Marketing, Competitive Retail and Renewable [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0
Corporate and Other [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		23.3	[6]	22.0	[7]
Corporate and Other [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		23.3		22.0
Corporate and Other [Member] | Alternative and Other [Member]
Disaggregation of Revenue
Total Revenues		2.2		2.0
Corporate and Other [Member] | Alternative [Member]
Disaggregation of Revenue
Total Revenues		0.0	[6]	0.0	[7]
Corporate and Other [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers	[19]	3.8		7.0
Total Revenues		$ 2.2	[6]	$ 2.0	[7]

[1] 2018 amounts have been revised to reflect the reclassification of certain customer accounts between Retail classes. This reclassification did not impact previously reported Total Retail Revenues. Management concluded that these prior period disclosure only errors were immaterial individually and in the aggregate.

[2] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for Generation & Marketing was $37 million. The remaining affiliated amounts were immaterial.

[3] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for Generation & Marketing was $27 million. The remaining affiliated amounts were immaterial.

[4] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEP Transmission Holdco was $162 million. The remaining affiliated amounts were immaterial.

[5] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEP Transmission Holdco was $198 million. The remaining affiliated amounts were immaterial.

[6] Amounts include affiliated and nonaffiliated revenues.

[7] Amounts include affiliated and nonaffiliated revenues.

[8] 2018 amounts have been revised to reflect the reclassification of certain customer accounts between Retail classes. This reclassification did not impact previously reported Total Retail Revenues. Management concluded that these prior period disclosure only errors were immaterial individually and in the aggregate.

[9] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for APCo was $35 million primarily relating to the PPA with KGPCo. The remaining affiliated amounts were immaterial.

[10] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for APCo was $40 million primarily relating to the PPA with KGPCo. The remaining affiliated amounts were immaterial.

[11] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEPTCo was $195 million. The remaining affiliated amounts were immaterial.

[12] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEPTCo was $160 million. The remaining affiliated amounts were immaterial.

[13] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for I&M was $15 million primarily relating to the barging, urea transloading and other transportation services. The remaining affiliated amounts were immaterial.

[14] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for I&M was $15 million primarily relating to the barging, urea transloading and other transportation services. The remaining affiliated amounts were immaterial.

[15] Amounts include affiliated and nonaffiliated revenues.

[16] Amounts include affiliated and nonaffiliated revenues.

[17] The amounts presented reflect the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.

[18] The amounts presented reflect the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.

[19] 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.