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Quarterly Financial Data (Unaudited) (Unusual or Infrequently Occurring Items) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	$ (33)	$ (56)	$ (61)	$ (55)	$ (72)	$ (88)	$ (82)	$ (55)	$ (205)	$ (297)
Pretax impairment charge									(81)us-gaap_AssetImpairmentCharges	(399)us-gaap_AssetImpairmentCharges	(666)us-gaap_AssetImpairmentCharges
Gain on sale of equity investment									17	100	22
Deferred foreign taxes									(67)	14	20
Total	(547)	421	(61)	(1,436)	(24)	(88)	(464)	(55)	(1,623)	(631)
Midwest Generation Impairment [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge	(39)	477		(1,287)					(849)
Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Coal ash Plea Agreements Reserve	(102)								(102)
International Tax Adjustment [Member]
Quarterly Financial Information Disclosure [Line Items]
Deferred foreign taxes	(373)								(373)
OVEC [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge				(94)					(94)
DukeNet [Member]
Quarterly Financial Information Disclosure [Line Items]
Gain on sale of equity investment					105					105
Crystal River Unit 3 Retirement [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge					(57)		(295)			(352)
Nuclear Development Charges [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge							(87)			(87)
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(17)	(25)	(38)	(29)	(29)	(34)	(35)	(22)	(109)	(120)
Pretax impairment charge									(3)		(31)
Total	(89)	(25)	(38)	(29)					(181)
Duke Energy Carolinas [Member] \| Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Coal ash Plea Agreements Reserve	(72)								(72)
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(13)	(21)	(12)	(19)	(28)	(42)	(33)	(19)	(65)	(122)
Pretax impairment charge									16	(380)	(200)
Total	(43)	(21)	(12)	(19)	(85)	(42)	(415)	(19)	(95)	(561)
Progress Energy [Member] \| Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Coal ash Plea Agreements Reserve	(30)								(30)
Progress Energy [Member] \| Crystal River Unit 3 Retirement [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge					(57)		(295)			(352)
Progress Energy [Member] \| Nuclear Development Charges [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge							(87)			(87)
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(10)	(15)	(3)	(14)	(19)	(32)	(22)	(11)	(42)	(84)
Pretax impairment charge									18	(22)	(54)
Total	(40)	(15)	(3)	(14)	(19)	(32)	(44)	(11)	(72)	(106)
Duke Energy Progress [Member] \| Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Coal ash Plea Agreements Reserve	(30)								(30)
Duke Energy Progress [Member] \| Nuclear Development Charges [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge							(22)			(22)
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(3)	(6)	(9)	(5)	(9)	(10)	(11)	(8)	(23)	(38)
Pretax impairment charge									(2)	(358)	(146)
Total					(66)	(10)	(371)	(8)		(455)
Duke Energy Florida [Member] \| Crystal River Unit 3 Retirement [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge					(57)		(295)			(352)
Duke Energy Florida [Member] \| Nuclear Development Charges [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge							(65)			(65)
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(2)	(3)	(4)	(2)	(4)	(4)	(4)	(4)	(11)	(16)
Pretax impairment charge									(94)	(5)	(2)
Total	(41)	474	(4)	(1,414)					(985)
Duke Energy Ohio [Member] \| Midwest Generation Impairment [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge	(39)	477		(1,318)					(880)
Duke Energy Ohio [Member] \| OVEC [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge				(94)					(94)
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(2)	(3)	(5)	(2)	(5)	(5)	(5)	(4)	(12)	(19)
Pretax impairment charge									$ 0	$ 0	$ (579)