Acquisitions and Dispositions Acquisitions and Dispositions (Plants in Disposal Group) (Details) - Duke Energy Ohio [Member]	3 Months Ended
	Mar. 31, 2015 MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	9,225
Owned Average MW Capacity	5,884
Stuart [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	2,308
Owned Average MW Capacity	900
Jointly Owned Utility Plant, Proportionate Ownership Share	39.00%
Zimmer [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,300
Owned Average MW Capacity	605
Jointly Owned Utility Plant, Proportionate Ownership Share	46.50%
Hanging Rock [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,226
Owned Average MW Capacity	1,226
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Miami Fort Station 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
Owned Average MW Capacity	652
Jointly Owned Utility Plant, Proportionate Ownership Share	64.00%
Conesville [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	780
Owned Average MW Capacity	312
Jointly Owned Utility Plant, Proportionate Ownership Share	40.00%
Washington [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	617
Owned Average MW Capacity	617
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Fayette [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	614
Owned Average MW Capacity	614
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Killen [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	600
Owned Average MW Capacity	198
Jointly Owned Utility Plant, Proportionate Ownership Share	33.00%
Lee [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	568
Owned Average MW Capacity	568
Jointly Owned Utility Plant, Proportionate Ownership Share	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
Owned Average MW Capacity	136
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Miami Fort [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	56
Owned Average MW Capacity	56
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%