Business Segments (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Reportable Segment Information
Revenues		$ 4,044.9	$ 4,580.4
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		503.1	620.2
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		0.0	10.5
NET INCOME (LOSS)		503.1	630.7
Balance Sheet Information
Total Property, Plant and Equipment		66,430.2		$ 65,481.4
Accumulated Depreciation and Amortization		19,597.3		19,348.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		46,832.9		46,133.2
Total Assets		62,486.5		61,683.1
Long-term Debt Due Within One Year - Affiliated		0.0		0.0
Long-term Debt Due Within One Year		2,033.3		1,831.8
Long-term Debt - Affiliated		0.0		0.0
Long-term Debt		17,749.3		17,740.9
Total Long-term Debt Outstanding		19,782.6		19,572.7
Vertically Integrated Utilities [Member]
Reportable Segment Information
Sales Revenue, Net		2,218.1	2,487.4
Revenues		2,245.6	2,505.1
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		278.7	300.3
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		0.0	0.0
NET INCOME (LOSS)		278.7	300.3
Balance Sheet Information
Total Property, Plant and Equipment		40,599.7		40,130.3
Accumulated Depreciation and Amortization		12,485.3		12,335.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		28,114.4		27,795.3
Total Assets		36,197.0		35,792.3
Long-term Debt Due Within One Year - Affiliated		0.0		0.0
Long-term Debt Due Within One Year		1,174.3		935.4
Long-term Debt - Affiliated		20.0		20.0
Long-term Debt		9,948.1		9,833.0
Total Long-term Debt Outstanding		11,142.4		10,788.4
Transmission And Distribution Companies [Member]
Reportable Segment Information
Sales Revenue, Net		1,077.3	1,206.3
Revenues		1,096.8	1,270.1
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		108.0	97.2
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		0.0	0.0
NET INCOME (LOSS)		108.0	97.2
Balance Sheet Information
Total Property, Plant and Equipment		14,029.4		13,840.5
Accumulated Depreciation and Amortization		3,573.5		3,529.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		10,455.9		10,311.3
Total Assets		14,341.3		14,640.2
Long-term Debt Due Within One Year - Affiliated		0.0		0.0
Long-term Debt Due Within One Year		786.3		824.7
Long-term Debt - Affiliated		0.0		0.0
Long-term Debt		4,665.6		4,776.8
Total Long-term Debt Outstanding		5,451.9		5,601.5
AEP Transmission Holdco [Member]
Reportable Segment Information
Sales Revenue, Net		29.3	21.7
Revenues		88.6	57.9
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		44.7	36.3
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		0.0	0.0
NET INCOME (LOSS)		44.7	36.3
Balance Sheet Information
Total Property, Plant and Equipment		4,230.5		3,977.6
Accumulated Depreciation and Amortization		63.9		52.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		4,166.6		3,925.3
Total Assets		5,152.7		5,012.1
Long-term Debt Due Within One Year - Affiliated		0.0		0.0
Long-term Debt Due Within One Year		0.0		0.0
Long-term Debt - Affiliated		0.0		0.0
Long-term Debt		1,654.1		1,648.4
Total Long-term Debt Outstanding		1,654.1		1,648.4
Generation And Marketing [Member]
Reportable Segment Information
Sales Revenue, Net		713.9	859.2
Revenues		748.0	1,170.5
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		70.7	187.4
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		0.0	0.0
NET INCOME (LOSS)		70.7	187.4
Balance Sheet Information
Total Property, Plant and Equipment		7,510.9		7,461.3
Accumulated Depreciation and Amortization		3,409.8		3,367.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		4,101.1		4,094.3
Total Assets		5,400.2		5,414.5
Long-term Debt Due Within One Year - Affiliated		0.0		0.0
Long-term Debt Due Within One Year		71.7		71.6
Long-term Debt - Affiliated		32.2		32.2
Long-term Debt		635.3		639.5
Total Long-term Debt Outstanding		739.2		743.3
All Other [Member]
Reportable Segment Information
Sales Revenue, Net	[1]	6.3	5.8
Revenues	[1]	24.4	26.2
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	[1]	1.0	(1.0)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	[1]	0.0	10.5
NET INCOME (LOSS)	[1]	1.0	9.5
Balance Sheet Information
Total Property, Plant and Equipment	[1]	357.3		350.9
Accumulated Depreciation and Amortization	[1]	180.8		176.9
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET	[1]	176.5		174.0
Total Assets	[1]	21,962.1		21,907.4
Long-term Debt Due Within One Year - Affiliated	[1]	0.0		0.0
Long-term Debt Due Within One Year	[1]	1.0		0.1
Long-term Debt - Affiliated	[1]	0.0		0.0
Long-term Debt	[1]	846.2		843.2
Total Long-term Debt Outstanding	[1]	847.2		843.3
Consolidation, Eliminations [Member]
Reportable Segment Information
Sales Revenue, Net		0.0	0.0
Revenues		(158.5)	(449.4)
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		0.0	0.0
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		0.0	0.0
NET INCOME (LOSS)		0.0	0.0
Balance Sheet Information
Total Property, Plant and Equipment	[2]	(297.6)		(279.2)
Accumulated Depreciation and Amortization	[2]	(116.0)		(112.2)
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET	[2]	(181.6)		(167.0)
Total Assets	[2],[3]	(20,566.8)		(21,083.4)
Long-term Debt Due Within One Year - Affiliated		0.0		0.0
Long-term Debt Due Within One Year		0.0		0.0
Long-term Debt - Affiliated		(52.2)		(52.2)
Long-term Debt		0.0		0.0
Total Long-term Debt Outstanding		(52.2)		$ (52.2)
Segment Reconciling Items [Member] | Vertically Integrated Utilities [Member]
Reportable Segment Information
Sales Revenue, Net		27.5	17.7
Segment Reconciling Items [Member] | Transmission And Distribution Companies [Member]
Reportable Segment Information
Sales Revenue, Net		19.5	63.8
Segment Reconciling Items [Member] | AEP Transmission Holdco [Member]
Reportable Segment Information
Sales Revenue, Net		59.3	36.2
Segment Reconciling Items [Member] | Generation And Marketing [Member]
Reportable Segment Information
Sales Revenue, Net		34.1	311.3
Segment Reconciling Items [Member] | All Other [Member]
Reportable Segment Information
Sales Revenue, Net	[1]	18.1	20.4
Segment Reconciling Items [Member] | Consolidation, Eliminations [Member]
Reportable Segment Information
Sales Revenue, Net		$ (158.5)	$ (449.4)

[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.