Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Disaggregation of Revenue
Revenue from Contracts with Customers		$ 14,918.5		$ 15,561.4		$ 16,195.7
Revenue, Performance Obligation
Fixed Performance Obligations		1,610.7
Revenues		14,918.5		15,561.4		16,195.7
Revenue Textuals
Revenue from Related Parties		0.0		0.0		0.0
Redemption of Noncontrolling Interest		(100.2)		0.0		0.0
2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		1,122.9
2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		164.1
2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		162.2
After 2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		161.5
Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		11,364.0		11,851.9		12,327.8	[1]
Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		5,693.7		5,713.6		5,941.2
Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3,064.8		3,308.2		3,435.1
Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,407.4		2,607.2		2,725.3
Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		198.1		222.9		226.2
Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3,209.7		3,444.2		3,435.7
Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		720.2		1,062.4		1,316.2
Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,051.8	[2]	979.4	[3]	766.5	[4]
Renewable Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		59.3	[5]	57.3	[6]	50.8	[7]
Retail, Trading and Marketing Revenue [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,378.4	[8]	1,345.1	[9]	1,302.2	[10]
Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		289.6	[5]	316.7	[6]	453.0	[7]
Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		14,863.3		15,612.8		16,216.5
Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		55.2		(51.4)		(20.8)
Alternative [Member]
Revenue, Performance Obligation
Revenues		(6.3)	[5]	(113.1)	[6]	(45.8)	[7]
Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		305.6		274.9		268.6
Revenue, Performance Obligation
Revenues		61.5	[5]	61.7	[6]	25.0	[7]
AEP Texas Inc. [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,528.0		1,551.6		1,493.0
Revenue, Performance Obligation
Fixed Performance Obligations		465.4
Revenues		1,618.9		1,709.3		1,595.3
Current Assets
Affiliated Companies - Contracts with Customers		5.1		10.1
Revenue Textuals
Revenue from Related Parties		90.8		160.5		105.2
AEP Texas Inc. [Member] | 2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		465.4
AEP Texas Inc. [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Texas Inc. [Member] | 2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Texas Inc. [Member] | After 2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Texas Inc. [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,079.9		1,142.3		1,151.0	[11]
AEP Texas Inc. [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		563.6		571.5		578.9
AEP Texas Inc. [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		366.7		411.5		414.7
AEP Texas Inc. [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		120.1		129.4		128.0
AEP Texas Inc. [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		29.5		29.9		29.4
AEP Texas Inc. [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		399.9		379.2		313.4
AEP Texas Inc. [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[12]	0.0	[13]	0.0	[14]
AEP Texas Inc. [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		399.9	[15]	379.2	[16]	313.4	[17]
AEP Texas Inc. [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		48.2	[18]	30.1	[19]	28.6	[20]
AEP Texas Inc. [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		90.9		157.7		102.3
AEP Texas Inc. [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		3.4	[21]	0.6	[22]	(1.3)	[23]
AEP Texas Inc. [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3.2		2.9		3.8
Revenue, Performance Obligation
Revenues		87.5	[21]	157.1	[22]	103.6	[23]
AEP Transmission Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,232.7		1,042.1		832.0
Revenue, Performance Obligation
Fixed Performance Obligations		1,319.5
Revenues		1,145.7		1,021.4		776.1
Current Assets
Affiliated Companies - Contracts with Customers		81.2		66.1
Revenue Textuals
Revenue from Related Parties		896.3		806.7		598.9
AEP Transmission Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		81.0		65.9
AEP Transmission Co [Member] | 2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		1,319.5
AEP Transmission Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Transmission Co [Member] | 2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
AEP Transmission Co [Member] | After 2025 [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		0.0	[11]
AEP Transmission Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,210.3		1,025.5		816.9
AEP Transmission Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[12]	0.0	[13]	0.0	[14]
AEP Transmission Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,210.3	[15]	1,025.5	[16]	816.9	[17]
Revenue Textuals
Revenue from Related Parties		952.0		782.0		646.0
AEP Transmission Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		22.4	[18]	16.6	[19]	15.1	[20]
AEP Transmission Co [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		(87.0)		(20.7)		(55.9)
AEP Transmission Co [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		(87.0)	[21]	(20.7)	[22]	(55.9)	[23]
AEP Transmission Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.6		0.1		0.2
Revenue, Performance Obligation
Revenues		0.0	[21]	0.0	[22]	0.0	[23]
Appalachian Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,809.2		2,911.1		2,993.2
Revenue, Performance Obligation
Fixed Performance Obligations		240.5
Revenues		2,796.2		2,924.7		2,967.5
Current Assets
Affiliated Companies - Contracts with Customers		64.3		64.3
Revenue Textuals
Revenue from Related Parties		174.7		205.3		181.4
Appalachian Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		52.7		47.3
Appalachian Power Co [Member] | 2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		173.4
Appalachian Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		32.3
Appalachian Power Co [Member] | 2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		23.2
Appalachian Power Co [Member] | After 2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		11.6
Appalachian Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,388.7		2,494.2		2,604.8	[11]
Appalachian Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,250.6		1,266.9		1,342.7
Appalachian Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		517.0		559.9		580.4
Appalachian Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		553.5		592.2		604.3
Appalachian Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		67.6		75.2		77.4
Appalachian Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		361.0		355.1		333.1
Appalachian Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		230.2	[12]	251.5	[13]	250.4	[14]
Revenue Textuals
Revenue from Related Parties		112.0		129.0		134.0
Appalachian Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		130.8	[15]	103.6	[16]	82.7	[17]
Appalachian Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		59.5	[18]	61.8	[19]	55.3	[20]
Appalachian Power Co [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		(13.0)		13.6		(25.7)
Appalachian Power Co [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		(13.0)	[21]	13.6	[22]	(23.8)	[23]
Appalachian Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		10.6		11.2		9.0
Revenue, Performance Obligation
Revenues		0.0	[21]	0.0	[22]	(1.9)	[23]
Indiana Michigan Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,236.0		2,308.1		2,381.0
Revenue, Performance Obligation
Fixed Performance Obligations		57.2
Revenues		2,241.8		2,306.7		2,370.7
Current Assets
Affiliated Companies - Contracts with Customers		51.3		53.7
Revenue Textuals
Revenue from Related Parties		10.5		10.5		22.1
Indiana Michigan Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		34.8		37.1
Indiana Michigan Power Co [Member] | 2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		35.1
Indiana Michigan Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		8.8
Indiana Michigan Power Co [Member] | 2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		8.8
Indiana Michigan Power Co [Member] | After 2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		4.5
Indiana Michigan Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,847.4		1,782.2		1,787.8	[11]
Indiana Michigan Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		794.1		730.0		730.0
Indiana Michigan Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		499.3		494.2		485.0
Indiana Michigan Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		547.4		550.7		565.6
Indiana Michigan Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		6.6		7.3		7.2
Indiana Michigan Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		303.6		427.5		493.6
Indiana Michigan Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		274.6	[12]	402.4	[13]	470.5	[14]
Indiana Michigan Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		29.0	[15]	25.1	[16]	23.1	[17]
Indiana Michigan Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		85.0	[18]	98.4	[19]	99.6	[20]
Indiana Michigan Power Co [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		5.8		(1.4)		(10.3)
Indiana Michigan Power Co [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		5.8	[21]	(1.4)	[22]	(2.1)	[23]
Indiana Michigan Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		5.2		10.7		12.6
Revenue, Performance Obligation
Revenues		0.0	[21]	0.0	[22]	(8.2)	[23]
Revenue Textuals
Revenue from Related Parties		69.0		73.0		70.0
Ohio Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,665.0		2,748.8		3,079.9
Revenue, Performance Obligation
Fixed Performance Obligations		68.2
Revenues		2,749.1		2,797.6		3,063.4
Current Assets
Affiliated Companies - Contracts with Customers		65.1		59.3
Revenue Textuals
Revenue from Related Parties		41.5		27.3		21.0
Ohio Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		45.9		33.9
Ohio Power Co [Member] | 2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		68.1
Ohio Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Ohio Power Co [Member] | 2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Ohio Power Co [Member] | After 2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.1
Ohio Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,488.5		2,553.5		2,845.3	[11]
Ohio Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,523.4		1,502.0		1,611.6
Ohio Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		682.0		738.5		835.6
Ohio Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		270.0		299.9		385.2
Ohio Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		13.1		13.1		12.9
Ohio Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		67.0		56.0		58.5
Ohio Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[12]	0.0	[13]	0.0	[14]
Ohio Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		67.0	[15]	56.0	[16]	58.5	[17]
Ohio Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		109.5	[18]	139.3	[19]	176.1	[20]
Ohio Power Co [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		84.1		48.8		(16.5)
Ohio Power Co [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		66.6	[21]	31.7	[22]	(20.8)	[23]
Ohio Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		9.0		10.8		8.6
Revenue, Performance Obligation
Revenues		17.5	[21]	17.1	[22]	4.3	[23]
Public Service Co Of Oklahoma [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,263.9		1,512.8		1,536.4
Revenue, Performance Obligation
Fixed Performance Obligations		14.8
Revenues		1,266.1		1,481.8		1,547.3
Current Assets
Affiliated Companies - Contracts with Customers		15.6		20.6
Revenue Textuals
Revenue from Related Parties		5.2		6.1		5.4
Public Service Co Of Oklahoma [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		7.8		9.7
Public Service Co Of Oklahoma [Member] | 2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		14.8
Public Service Co Of Oklahoma [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Public Service Co Of Oklahoma [Member] | 2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Public Service Co Of Oklahoma [Member] | After 2025 [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		1,186.6		1,423.8		1,440.8	[11]
Public Service Co Of Oklahoma [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		579.4		650.2		659.0
Public Service Co Of Oklahoma [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		320.1		388.5		394.2
Public Service Co Of Oklahoma [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		221.1		303.5		304.0
Public Service Co Of Oklahoma [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		66.0		81.6		83.6
Public Service Co Of Oklahoma [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		42.6		67.0		76.5
Public Service Co Of Oklahoma [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		15.1	[12]	39.5	[13]	36.3	[14]
Public Service Co Of Oklahoma [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		27.5	[15]	27.5	[16]	40.2	[17]
Public Service Co Of Oklahoma [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		34.7	[18]	22.0	[19]	19.1	[20]
Public Service Co Of Oklahoma [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		2.2		(31.0)		10.9
Public Service Co Of Oklahoma [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		2.2	[21]	(31.0)	[22]	10.9	[23]
Public Service Co Of Oklahoma [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		14.8		6.1		4.3
Revenue, Performance Obligation
Revenues		0.0	[21]	0.0	[22]	0.0	[23]
Southwestern Electric Power Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,735.3		1,799.2		1,817.0
Revenue, Performance Obligation
Fixed Performance Obligations		41.6
Revenues		1,738.5		1,750.9		1,821.9
Current Assets
Affiliated Companies - Contracts with Customers		25.1		34.5
Revenue Textuals
Revenue from Related Parties		41.0		36.9		35.1
Southwestern Electric Power Co [Member] | Short-term Contract with Customer [Member]
Current Assets
Affiliated Companies - Contracts with Customers		11.2		17.6
Southwestern Electric Power Co [Member] | 2021 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		41.6
Southwestern Electric Power Co [Member] | 2022-2023 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Southwestern Electric Power Co [Member] | 2024-2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Southwestern Electric Power Co [Member] | After 2025 [Member]
Revenue, Performance Obligation
Fixed Performance Obligations		0.0
Southwestern Electric Power Co [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,435.4		1,471.7		1,467.8	[11]
Southwestern Electric Power Co [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		630.8		638.6		641.6
Southwestern Electric Power Co [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		466.7		485.4		483.9
Southwestern Electric Power Co [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		328.8		338.7		333.7
Southwestern Electric Power Co [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		9.1		9.0		8.6
Southwestern Electric Power Co [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		273.2		301.4		325.2
Southwestern Electric Power Co [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		162.0	[12]	194.7	[13]	216.8	[14]
Southwestern Electric Power Co [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		111.2	[15]	106.7	[16]	108.4	[17]
Southwestern Electric Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		26.7	[18]	26.1	[19]	24.0	[20]
Southwestern Electric Power Co [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		3.2		(48.3)		4.9
Southwestern Electric Power Co [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		3.2	[21]	(48.3)	[22]	4.9	[23]
Southwestern Electric Power Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.9		1.4		1.6
Revenue, Performance Obligation
Revenues		0.0	[21]	0.0	[22]	0.0	[23]
Consolidation Eliminations [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Revenue, Performance Obligation
Revenues		(1,328.0)		(1,314.8)		(942.4)
Revenue Textuals
Revenue from Related Parties		(1,328.0)		(1,314.8)		(942.4)
Consolidation Eliminations [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(0.7)		(0.9)		0.0	[1]
Consolidation Eliminations [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Consolidation Eliminations [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Consolidation Eliminations [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(0.7)		(0.9)		0.0
Consolidation Eliminations [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Consolidation Eliminations [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(1,111.3)		(960.6)		(865.1)
Consolidation Eliminations [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		(7.3)	[24]
Consolidation Eliminations [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(1,006.7)	[2]	(825.0)	[3]	(737.1)	[4]
Consolidation Eliminations [Member] | Renewable Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(1.6)	[5]	0.0	[6]	0.0	[7]
Consolidation Eliminations [Member] | Retail, Trading and Marketing Revenue [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(103.0)	[8]	(135.6)	[9]	(120.7)	[10]
Consolidation Eliminations [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(148.6)	[5]	(147.1)	[6]	(32.0)	[7]
Consolidation Eliminations [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(1,260.6)		(1,108.6)		(897.1)
Consolidation Eliminations [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		(67.4)		(206.2)		(45.3)
Consolidation Eliminations [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		7.5	[5]	(66.9)	[6]	52.7	[7]
Consolidation Eliminations [Member] | Other Revenues [Member]
Revenue, Performance Obligation
Revenues		(74.9)	[5]	(139.3)	[6]	(98.0)	[7],[24]
Consolidation Eliminations [Member] | AEP Transmission Co [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Revenue, Performance Obligation
Revenues		0.0		0.0		0.0
Revenue Textuals
Revenue from Related Parties		0.0		0.0		0.0
Consolidation Eliminations [Member] | AEP Transmission Co [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Vertically Integrated Utilities [Member]
Revenue, Performance Obligation
Revenues		8,879.4		9,367.1		9,645.5
Revenue Textuals
Revenue from Related Parties		126.2		121.4		88.8
Vertically Integrated Utilities [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		7,796.6		8,157.1		8,331.5	[1]
Vertically Integrated Utilities [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3,606.8		3,643.7		3,751.8
Vertically Integrated Utilities [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,016.2		2,155.3		2,183.4
Vertically Integrated Utilities [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,018.0		2,179.0		2,212.8
Vertically Integrated Utilities [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		155.6		179.1		183.5
Vertically Integrated Utilities [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		922.8		1,099.7		1,182.0
Vertically Integrated Utilities [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		588.3		807.6		899.8
Vertically Integrated Utilities [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		334.5	[2]	292.1	[3]	282.2	[4]
Vertically Integrated Utilities [Member] | Renewable Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[5]	0.0	[6]	0.0	[7]
Vertically Integrated Utilities [Member] | Retail, Trading and Marketing Revenue [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[8]	0.0	[9]	0.0	[10]
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		163.2	[5]	168.2	[6]	158.4	[7]
Vertically Integrated Utilities [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		8,882.6		9,425.0		9,671.9
Vertically Integrated Utilities [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		(3.2)		(57.9)		(26.4)
Vertically Integrated Utilities [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		(3.2)	[5]	(57.9)	[6]	(15.9)	[7]
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Revenue, Performance Obligation
Revenues		0.0	[5]	0.0	[6]	(10.5)	[7]
Transmission And Distribution Utilities [Member]
Revenue, Performance Obligation
Revenues		4,345.9		4,482.5		4,653.1
Revenue Textuals
Revenue from Related Parties		107.2		163.5		100.8
Transmission And Distribution Utilities [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		3,568.1		3,695.7		3,996.3	[1]
Transmission And Distribution Utilities [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2,086.9		2,069.9		2,189.4
Transmission And Distribution Utilities [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,048.6		1,152.9		1,251.7
Transmission And Distribution Utilities [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		390.1		429.1		512.5
Transmission And Distribution Utilities [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		42.5		43.8		42.7
Transmission And Distribution Utilities [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		467.0		435.1		372.1
Transmission And Distribution Utilities [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Transmission And Distribution Utilities [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		467.0	[2]	435.1	[3]	372.1	[4]
Transmission And Distribution Utilities [Member] | Renewable Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[5]	0.0	[6]	0.0	[7]
Transmission And Distribution Utilities [Member] | Retail, Trading and Marketing Revenue [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[8]	0.0	[9]	0.0	[10]
Transmission And Distribution Utilities [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		157.8	[5]	169.4	[6]	204.6	[7]
Transmission And Distribution Utilities [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		4,192.9		4,300.2		4,573.0
Transmission And Distribution Utilities [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		153.0		182.3		80.1
Transmission And Distribution Utilities [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		70.0	[5]	32.3	[6]	(22.2)	[7]
Transmission And Distribution Utilities [Member] | Other Revenues [Member]
Revenue, Performance Obligation
Revenues		83.0	[5]	150.0	[6]	102.3	[7]
AEP Transmission Holdco [Member]
Revenue, Performance Obligation
Revenues		1,198.8		1,073.2		804.1
AEP Transmission Holdco [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0	[1]
AEP Transmission Holdco [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Holdco [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Holdco [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Holdco [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Holdco [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,257.0		1,077.2		849.3
AEP Transmission Holdco [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
AEP Transmission Holdco [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,257.0	[2]	1,077.2	[3]	849.3	[4]
Revenue Textuals
Revenue from Related Parties		965.0		794.0		643.0
AEP Transmission Holdco [Member] | Renewable Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[5]	0.0	[6]	0.0	[7]
AEP Transmission Holdco [Member] | Retail, Trading and Marketing Revenue [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[8]	0.0	[9]	0.0	[10]
AEP Transmission Holdco [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		22.4	[5]	16.6	[6]	15.2	[7]
AEP Transmission Holdco [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,279.4		1,093.8		864.5
AEP Transmission Holdco [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		(80.6)		(20.6)		(60.4)
AEP Transmission Holdco [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		(80.6)	[5]	(20.6)	[6]	(60.4)	[7]
AEP Transmission Holdco [Member] | Other Revenues [Member]
Revenue, Performance Obligation
Revenues		0.0	[5]	0.0	[6]	0.0	[7]
Generation and Marketing [Member]
Revenue, Performance Obligation
Revenues		1,725.6		1,857.6		1,940.3
Revenue Textuals
Revenue from Related Parties		104.6		135.8		122.2
Generation and Marketing [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0	[1]
Generation and Marketing [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Generation and Marketing [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Generation and Marketing [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Generation and Marketing [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Generation and Marketing [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,679.7		1,792.8		1,897.4
Generation and Marketing [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		131.9		254.8		423.7
Generation and Marketing [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[2]	0.0	[3]	0.0	[4]
Generation and Marketing [Member] | Renewable Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		60.9	[5]	57.3	[6]	50.8	[7]
Generation and Marketing [Member] | Retail, Trading and Marketing Revenue [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,486.9	[8]	1,480.7	[9]	1,422.9	[10]
Revenue Textuals
Revenue from Related Parties		103.0		136.0		121.0
Generation and Marketing [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		2.3	[5]	4.9	[6]	20.6	[7]
Generation and Marketing [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		1,682.0		1,797.7		1,918.0
Generation and Marketing [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		43.6		59.9		22.3
Generation and Marketing [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		0.0	[5]	0.0	[6]	0.0	[7]
Generation and Marketing [Member] | Other Revenues [Member]
Revenue, Performance Obligation
Revenues		43.6	[5]	59.9	[6]	22.3	[7]
Other Segments [Member]
Revenue, Performance Obligation
Revenues	[25]	96.8		95.8		95.1
Revenue Textuals
Revenue from Related Parties	[25]	88.6		81.1		75.1
Other Segments [Member] | Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0	[1]
Other Segments [Member] | Residential [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Other Segments [Member] | Commercial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Other Segments [Member] | Industrial [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Other Segments [Member] | Other Retail [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Other Segments [Member] | Wholesale and Competitive [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(5.5)		0.0		0.0
Other Segments [Member] | Wholesale Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0		0.0		0.0
Other Segments [Member] | Wholesale Transmission [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[2]	0.0	[3]	0.0	[4]
Other Segments [Member] | Renewable Generation [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		0.0	[5]	0.0	[6]	0.0	[7]
Other Segments [Member] | Retail, Trading and Marketing Revenue [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		(5.5)	[8]	0.0	[9]	0.0	[10]
Other Segments [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		92.5	[5]	104.7	[6]	86.2	[7]
Other Segments [Member] | Affiliated and Nonaffiliated [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers		87.0		104.7		86.2
Other Segments [Member] | Alternative and Other [Member]
Revenue, Performance Obligation
Revenues		9.8		(8.9)		8.9
Other Segments [Member] | Alternative [Member]
Revenue, Performance Obligation
Revenues		0.0	[5]	0.0	[6]	0.0	[7]
Other Segments [Member] | Other Revenues [Member]
Disaggregation of Revenue
Revenue from Contracts with Customers	[25]	8.2		14.7		20.0
Revenue, Performance Obligation
Revenues		$ 9.8	[5]	$ (8.9)	[6]	8.9	[7]
Consolidation Eliminations [Member] | Other Revenues [Member]
Revenue Textuals
Revenue from Related Parties						$ 98.0

[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 AEP Transmission Holdco was $965 million. The remaining affiliated amounts were immaterial.

[3] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEP Transmission Holdco was $794 million. The remaining affiliated amounts were immaterial.

[4] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEP Transmission Holdco was $643 million. The remaining affiliated amounts were immaterial.

[5] Amounts include affiliated and nonaffiliated revenues.

[6] Amounts include affiliated and nonaffiliated revenues.

[7] Amounts include affiliated and nonaffiliated revenues.

[8] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for Generation & Marketing was $103 million. The remaining affiliated amounts were immaterial.

[9] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for Generation & Marketing was $136 million. The remaining affiliated amounts were immaterial.

[10] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for Generation & Marketing was $121 million. The remaining affiliated amounts were immaterial.

[11] 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.

[12] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for APCo was $112 million primarily relating to the PPA with KGPCo. The remaining affiliated amounts were immaterial.

[13] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for APCo was $129 million primarily relating to the PPA with KGPCo. The remaining affiliated amounts were immaterial.

[14] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for APCo was $134 million primarily relating to the PPA with KGPCo. The remaining affiliated amounts were immaterial.

[15] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEPTCo was $952 million. The remaining affiliated amounts were immaterial.

[16] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEPTCo was $782 million. The remaining affiliated amounts were immaterial.

[17] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEPTCo was $646 million. The remaining affiliated amounts were immaterial

[18] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for I&M was $69 million primarily relating to barging, urea transloading and other transportation services. The remaining affiliated amounts were immaterial.

[19] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for I&M was $73 million primarily relating to barging, urea transloading and other transportation services. The remaining affiliated amounts were immaterial.

[20] Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for I&M was $70 million primarily relating to barging, urea transloading and other transportation services. The remaining affiliated amounts were immaterial

[21] Amounts include affiliated and nonaffiliated revenues.

[22] Amounts include affiliated and nonaffiliated revenues.

[23] Amounts include affiliated and nonaffiliated revenues.

[24] 2018 amounts have been revised to reflect the reclassification of $98 million of affiliated revenues between Generation Revenues and Other Revenues. This reclassification did not impact previously reported Total Revenues. Management concluded that these prior period disclosure only errors were immaterial individually and in the aggregate.

[25] 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, interest expense and other nonallocated costs.