Quarterly Financial Data (Unaudited) (Unusual or Infrequently Occurring Items) (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Oct. 31, 2016	Sep. 30, 2016	Jul. 31, 2016	Jun. 30, 2016	Apr. 30, 2016	Mar. 31, 2016	Jan. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016	Dec. 31, 2015	Oct. 31, 2015
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		$ (34)	$ (23)	$ (30)	$ (16)									$ (103)
Costs to achieve mergers, acquisition costs						$ (208)		$ (84)		$ (111)		$ (120)			$ (523)
Asset Impairment Charges														(282)	(18)		$ (106)
Net Income (Loss) Attributable to Parent		703	954	686	716	(227)		1,176		509		694		3,059	2,152		2,816
(Loss) Income from Discontinued Operations, net of tax		(2)	(2)	(2)		(598)		180		(112)		122		(6)	(408)		177
Cost Savings Initiative						(29)		(19)		(24)		(20)			(92)
Tax Act														(112)
Total		27	(242)	(30)	(16)	(751)		(174)		(329)		(140)		(261)	(1,394)
Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges			(135)
Utilities Operating Expense, Impairments		(23)												(158)
Commercial Renewables Impairment [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges		(18)	(84)					(71)						(102)	(71)
Impacts of the Tax Act [Member]
Quarterly Financial Information Disclosure [Line Items]
Net Income (Loss) Attributable to Parent		102												102
Loss on Disposal Group [Member]
Quarterly Financial Information Disclosure [Line Items]
Discontinued Operation, Provision for Loss (Gain) on Disposal, before Income Tax						514									514
Central America Impairment [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges										(194)					(194)
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(5)	(5)	(6)	(4)									(20)
Costs to achieve mergers, acquisition costs						(68)		(13)		(12)		(11)			(104)
Asset Impairment Charges															(1)		(1)
Net Income (Loss) Attributable to Parent		205	466	273	270	140		494		261		271		1,214	1,166		1,081
Cost Savings Initiative						(11)		(8)		(10)		(10)			(39)
Tax Act		15												15
Total		(20)	(5)	(6)	(4)	(79)		(21)		(22)		(21)		(35)	(143)
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(6)	(6)	(7)	(4)									(23)
Costs to achieve mergers, acquisition costs						(44)		(10)		(8)		(7)			(69)
Asset Impairment Charges														(156)	(7)		(12)
Net Income (Loss) Attributable to Parent		444	341	274	199	104		446		272		209		1,258	1,031		1,051
(Loss) Income from Discontinued Operations, net of tax															2		(3)
Cost Savings Initiative						(14)		(10)		(8)		(8)			(40)
Tax Act		(246)												(246)
Total		217	(141)	(7)	(4)	(58)		(20)		(16)		(15)		65	(109)
Progress Energy [Member] | Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges			(135)
Utilities Operating Expense, Impairments		(23)												(158)
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(4)	(4)	(4)	(2)									(14)
Costs to achieve mergers, acquisition costs						(40)		(6)		(5)		(5)			(56)
Asset Impairment Charges														(19)	(1)		(5)
Net Income (Loss) Attributable to Parent		168	246	154	147	60		271		131		137		715	599		566
Cost Savings Initiative						(6)		(7)		(5)		(5)			(23)
Tax Act		(40)												(40)
Total		13	(4)	(4)	(2)	(46)		(13)		(10)		(10)		3	(79)
Duke Energy Progress [Member] | Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Utilities Operating Expense, Impairments		(23)												(23)
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(2)	(2)	(3)	(2)									(9)
Costs to achieve mergers, acquisition costs						(4)		(4)		(3)		(2)			(13)
Asset Impairment Charges														(138)	(6)		(7)
Net Income (Loss) Attributable to Parent		344	120	158	90	64		206		171		110		712	551		599
Cost Savings Initiative						(9)		(3)		(3)		(2)			(17)
Tax Act		(226)												(226)
Total		224	(137)	(3)	(2)	(13)		(7)		(6)		(4)		82	(30)
Duke Energy Florida [Member] | Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges			(135)											(135)
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(2)	(2)	(1)	(1)									(6)
Costs to achieve mergers, acquisition costs						(2)		(2)		(1)		(1)			(6)
Asset Impairment Charges														(1)
Net Income (Loss) Attributable to Parent		65	55	30	42	57		89		23		59		192	228		172
(Loss) Income from Discontinued Operations, net of tax			(1)					34				2		(1)	36		23
Cost Savings Initiative						(1)				(1)		(1)			(3)
Tax Act		(23)												(23)
Total		21	(2)	(1)	(1)	(3)		(2)		(2)		(2)		17	(9)
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(1)	(2)	(2)	(1)									(6)
Costs to achieve mergers, acquisition costs						(3)		(3)		(2)		(1)			(9)
Asset Impairment Charges														(18)	(8)		(88)
Net Income (Loss) Attributable to Parent		36	121	106	91	72		129		85		95		354	381		$ 316
Cost Savings Initiative						(1)		(1)		(4)		(1)			(7)
Tax Act		55												55
Total		(56)	(2)	(2)	(1)	$ (4)		$ (4)		$ (6)		$ (2)		(61)	$ (16)
Piedmont Natural Gas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(19)	(8)	(13)	(6)									(46)
Costs to achieve mergers, acquisition costs	$ (7)						$ (53)		$ (1)		$ (2)		$ (6)			$ (62)
Asset Impairment Charges														(7)
Net Income (Loss) Attributable to Parent	$ 54	63	(11)	(8)	95		$ 39		$ (7)		$ 63		$ 98	139		$ 193		$ 137
Tax Act														(12)
Total		(17)	$ (8)	$ (13)	$ (6)									(44)
Piedmont Natural Gas [Member] | Impacts of the Tax Act [Member]
Quarterly Financial Information Disclosure [Line Items]
Net Income (Loss) Attributable to Parent		$ 2												$ 2