Business Segments (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Reportable Segment Information
Revenues		$ 4,652.2	$ 4,431.4	$ 12,590.0	$ 12,838.5
Income (Loss) from Continuing Operations		(764.2)	511.8	245.3	1,563.4
Income (Loss) from Discontinued Operations, Net of Tax		0.0	7.8	(2.5)	18.2
Net Income (Loss)		(764.2)	519.6	242.8	1,581.6
Balance Sheet Information
Total Property, Plant and Equipment		60,599.8		60,599.8		$ 65,481.4
Accumulated Depreciation and Amortization		16,337.6		16,337.6		19,348.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		44,262.2		44,262.2		46,133.2
Assets Held for Sale		1,915.3		1,915.3
Total Assets		61,442.0		61,442.0		61,683.1
Long-term Debt Due Within One Year		2,384.8		2,384.8		1,831.8
Long-term Debt - Affiliated		0.0		0.0		0.0
Long-term Debt		17,319.9		17,319.9		17,740.9
Total Long-term Debt Outstanding		19,704.7		19,704.7		19,572.7
Liabilities Held for Sale		231.0		231.0
Vertically Integrated Utilities [Member]
Reportable Segment Information
Sales Revenue, Net		2,538.3	2,435.8	6,864.6	7,081.8
Revenues		2,556.3	2,471.5	6,927.8	7,159.1
Income (Loss) from Continuing Operations		343.4	274.5	832.6	782.7
Income (Loss) from Discontinued Operations, Net of Tax		0.0	0.0	0.0	0.0
Net Income (Loss)		343.4	274.5	832.6	782.7
Balance Sheet Information
Total Property, Plant and Equipment		41,015.6		41,015.6		40,130.3
Accumulated Depreciation and Amortization		12,549.8		12,549.8		12,335.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		28,465.8		28,465.8		27,795.3
Assets Held for Sale		0.0		0.0
Total Assets		36,924.3		36,924.3		35,792.3
Long-term Debt Due Within One Year		1,611.0		1,611.0		935.4
Long-term Debt - Affiliated		20.0		20.0		20.0
Long-term Debt		10,067.3		10,067.3		9,833.0
Total Long-term Debt Outstanding		11,698.3		11,698.3		10,788.4
Liabilities Held for Sale		0.0		0.0
Transmission And Distribution Utilities [Member]
Reportable Segment Information
Sales Revenue, Net		1,245.4	1,163.6	3,398.9	3,377.9
Revenues		1,275.6	1,188.6	3,468.5	3,519.4
Income (Loss) from Continuing Operations		155.5	113.0	388.1	287.8
Income (Loss) from Discontinued Operations, Net of Tax		0.0	0.0	0.0	0.0
Net Income (Loss)		155.5	113.0	388.1	287.8
Balance Sheet Information
Total Property, Plant and Equipment		14,438.4		14,438.4		13,840.5
Accumulated Depreciation and Amortization		3,647.4		3,647.4		3,529.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		10,791.0		10,791.0		10,311.3
Assets Held for Sale		0.0		0.0
Total Assets		14,155.7		14,155.7		14,640.2
Long-term Debt Due Within One Year		268.3		268.3		824.7
Long-term Debt - Affiliated		0.0		0.0		0.0
Long-term Debt		4,745.3		4,745.3		4,776.8
Total Long-term Debt Outstanding		5,013.6		5,013.6		5,601.5
Liabilities Held for Sale		0.0		0.0
AEP Transmission Holdco [Member]
Reportable Segment Information
Sales Revenue, Net		39.5	26.9	110.1	74.1
Revenues		132.4	87.5	382.7	244.9
Income (Loss) from Continuing Operations		69.5	45.9	209.5	147.7
Income (Loss) from Discontinued Operations, Net of Tax		0.0	0.0	0.0	0.0
Net Income (Loss)		69.5	45.9	209.5	147.7
Balance Sheet Information
Total Property, Plant and Equipment		4,896.4		4,896.4		3,977.6
Accumulated Depreciation and Amortization		88.2		88.2		52.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		4,808.2		4,808.2		3,925.3
Assets Held for Sale		0.0		0.0
Total Assets		5,780.5		5,780.5		5,012.1
Long-term Debt Due Within One Year		0.0		0.0		0.0
Long-term Debt - Affiliated		0.0		0.0		0.0
Long-term Debt		1,660.4		1,660.4		1,648.4
Total Long-term Debt Outstanding		1,660.4		1,660.4		1,648.4
Liabilities Held for Sale		0.0		0.0
Generation And Marketing [Member]
Reportable Segment Information
Sales Revenue, Net		823.3	801.8	2,192.5	2,288.6
Revenues		859.4	836.0	2,291.2	2,806.7
Income (Loss) from Continuing Operations		(1,369.2)	91.6	(1,248.8)	360.3
Income (Loss) from Discontinued Operations, Net of Tax		0.0	0.0	0.0	0.0
Net Income (Loss)		(1,369.2)	91.6	(1,248.8)	360.3
Balance Sheet Information
Total Property, Plant and Equipment		234.3		234.3		7,461.3
Accumulated Depreciation and Amortization		44.2		44.2		3,367.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		190.1		190.1		4,094.3
Assets Held for Sale		1,915.3		1,915.3
Total Assets		3,176.6		3,176.6		5,414.5
Long-term Debt Due Within One Year		505.2		505.2		71.6
Long-term Debt - Affiliated		32.2		32.2		32.2
Long-term Debt		0.0		0.0		639.5
Total Long-term Debt Outstanding		537.4		537.4		743.3
Liabilities Held for Sale		231.0		231.0
All Other [Member]
Reportable Segment Information
Sales Revenue, Net	[1]	5.7	3.3	23.9	16.1
Revenues	[1]	24.8	23.8	79.1	73.9
Income (Loss) from Continuing Operations	[1]	36.6	(13.2)	63.9	(15.1)
Income (Loss) from Discontinued Operations, Net of Tax	[1]	0.0	7.8	(2.5)	18.2
Net Income (Loss)	[1]	36.6	(5.4)	61.4	3.1
Balance Sheet Information
Total Property, Plant and Equipment	[1]	368.6		368.6		350.9
Accumulated Depreciation and Amortization	[1]	192.1		192.1		176.9
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET	[1]	176.5		176.5		174.0
Assets Held for Sale		0.0		0.0
Total Assets	[1]	21,772.4		21,772.4		21,907.4
Long-term Debt Due Within One Year	[1]	0.3		0.3		0.1
Long-term Debt - Affiliated	[1]	0.0		0.0		0.0
Long-term Debt	[1]	846.9		846.9		843.2
Total Long-term Debt Outstanding	[1]	847.2		847.2		843.3
Liabilities Held for Sale		0.0		0.0
Segment Reconciling Items [Member]
Reportable Segment Information
Sales Revenue, Net		(196.3)	(176.0)	(559.3)	(965.5)
Segment Reconciling Items [Member] | Vertically Integrated Utilities [Member]
Reportable Segment Information
Sales Revenue, Net		18.0	35.7	63.2	77.3
Segment Reconciling Items [Member] | Transmission And Distribution Utilities [Member]
Reportable Segment Information
Sales Revenue, Net		30.2	25.0	69.6	141.5
Segment Reconciling Items [Member] | AEP Transmission Holdco [Member]
Reportable Segment Information
Sales Revenue, Net		92.9	60.6	272.6	170.8
Segment Reconciling Items [Member] | Generation And Marketing [Member]
Reportable Segment Information
Sales Revenue, Net		36.1	34.2	98.7	518.1
Segment Reconciling Items [Member] | All Other [Member]
Reportable Segment Information
Sales Revenue, Net	[1]	19.1	20.5	55.2	57.8
Consolidation, Eliminations [Member]
Reportable Segment Information
Sales Revenue, Net		0.0	0.0	0.0	0.0
Revenues		(196.3)	(176.0)	(559.3)	(965.5)
Income (Loss) from Continuing Operations		0.0	0.0	0.0	0.0
Income (Loss) from Discontinued Operations, Net of Tax		0.0	0.0	0.0	0.0
Net Income (Loss)		0.0	$ 0.0	0.0	$ 0.0
Balance Sheet Information
Total Property, Plant and Equipment	[2]	(353.5)		(353.5)		(279.2)
Accumulated Depreciation and Amortization	[2]	(184.1)		(184.1)		(112.2)
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET	[2]	(169.4)		(169.4)		(167.0)
Assets Held for Sale		0.0		0.0
Total Assets	[2],[3]	(20,367.5)		(20,367.5)		(21,083.4)
Long-term Debt Due Within One Year		0.0		0.0		0.0
Long-term Debt - Affiliated		(52.2)		(52.2)		(52.2)
Long-term Debt		0.0		0.0		0.0
Total Long-term Debt Outstanding		(52.2)		(52.2)		$ (52.2)
Liabilities Held for Sale		$ 0.0		$ 0.0

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

[2] Includes eliminations due to an intercompany capital lease.

[3] Reconciling Adjustments for Total Assets primarily include the elimination of intercompany advances to affiliates and intercompany accounts receivable along with the elimination of AEP’s investments in subsidiary companies.