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Business Segments (Business Segment Data) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	$ 6,065us-gaap_SalesRevenueNet	$ 6,263us-gaap_SalesRevenueNet
Segment income	773	746
Add back noncontrolling interests component	3	4
Income (Loss) From Discontinued Operations, net of tax	91	(843)
Net income (loss) attributable to parent	864us-gaap_NetIncomeLoss	(97)us-gaap_NetIncomeLoss
Net income (loss)	867us-gaap_ProfitLoss	(93)us-gaap_ProfitLoss
Segment assets	122,142us-gaap_Assets		120,709us-gaap_Assets
Impairment charges	0us-gaap_AssetImpairmentCharges	96us-gaap_AssetImpairmentCharges
Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	5,713	5,795
International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	273	382
Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	73	81
Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6	5
Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6,059	6,258
Operating Segments [Member] \| Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	5,723	5,805
Segment income	774	737
Segment assets	106,642
Operating Segments [Member] \| International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	273	382
Segment income	36	130
Segment assets	4,892
Operating Segments [Member] \| Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	73	81
Segment income	1	(32)
Segment assets	6,202
Operating Segments [Member] \| Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6,069	6,268
Segment income	811	835
Segment assets	117,736
Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(31)	(30)
Segment income	(1)	(2)
Segment assets	176
Intersegment Eliminations [Member] \| Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(10)	(10)
Intersegment Eliminations [Member] \| Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(21)	(20)
Intersegment Eliminations [Member] \| Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(10)	(10)
Corporate, Non-Segment [Member] \| Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	27	25
Segment income	(37)	(87)
Segment assets	4,230
Costs to achieve Progress Energy merger	13	34
Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	586	575
Segment income	59	(15)
Income (Loss) From Discontinued Operations, net of tax	90	(875)
Net income (loss) attributable to parent	149	(890)
Segment assets	9,796		9,999
Impairment charges		94
Duke Energy Ohio [Member] \| Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	572	562
Duke Energy Ohio [Member] \| Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	14	13
Duke Energy Ohio [Member] \| Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	586	575
Duke Energy Ohio [Member] \| Operating Segments [Member] \| Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	572	562
Segment income	70	61
Segment assets	6,782
Duke Energy Ohio [Member] \| Operating Segments [Member] \| Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	14	13
Segment income	(9)	(74)
Segment assets	2,984
Duke Energy Ohio [Member] \| Operating Segments [Member] \| Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	586	575
Segment income	61	(13)
Segment assets	9,766
Duke Energy Ohio [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment assets	(13)
Duke Energy Ohio [Member] \| Corporate, Non-Segment [Member] \| Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment income	(2)	(2)
Segment assets	43
Duke Energy Ohio [Member] \| Other VIEs [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges		94	94
Duke Energy Ohio [Member] \| Other VIEs [Member] \| Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges		$ 94