Acquisitions and Dispositions (Plants in Disposal Group) (Details) (Duke Energy Ohio [Member])	9 Months Ended
	Sep. 30, 2014 MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	9,469	[1]
Owned Average MW Capacity	6,090	[1]
Stuart [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	2,318	[1],[2],[3]
Owned Average MW Capacity	904	[1],[2],[3]
Ownership Interest	39.00%	[2],[3]
Zimmer [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,338	[1],[3]
Owned Average MW Capacity	622	[1],[3]
Ownership Interest	46.50%	[3]
Hanging Rock [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,274	[1]
Owned Average MW Capacity	1,274	[1]
Ownership Interest	100.00%
Miami Fort Units 7 and 8 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,020	[1],[3]
Owned Average MW Capacity	653	[1],[3]
Ownership Interest	64.00%	[3]
Conesville [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	780	[1],[2],[3]
Owned Average MW Capacity	312	[1],[2],[3]
Ownership Interest	40.00%	[2],[3]
Washington [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	637	[1]
Owned Average MW Capacity	637	[1]
Ownership Interest	100.00%
Fayette [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	640	[1]
Owned Average MW Capacity	640	[1]
Ownership Interest	100.00%
Killen [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	618	[1],[2],[3]
Owned Average MW Capacity	204	[1],[2],[3]
Ownership Interest	33.00%	[2],[3]
Lee [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	640	[1]
Owned Average MW Capacity	640	[1]
Ownership Interest	100.00%
Dicks Creek [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	136	[1]
Owned Average MW Capacity	136	[1]
Ownership Interest	100.00%
Miami Fort [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	68	[1]
Owned Average MW Capacity	68	[1]
Ownership Interest	100.00%

[1] Average MW capacity is calculated as the average of winter capacity and summer capacity.

[2] Station is not operated by Duke Energy Ohio.

[3] Jointly owned with Ohio Power Company and/or The Dayton Power & Light Company.