Goodwill and Intangible Assets (Goodwill By Reportable Operating Segment) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Gross		$ 19,425	$ 19,425
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		19,396
Goodwill, Impaired, Accumulated Impairment Loss		(122)	(29)
Goodwill, balance at end of period		19,303
Electric Utilities and Infrastructure [Member]
Goodwill [Line Items]
Goodwill, Gross		17,379	17,379
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		17,379
Goodwill, balance at end of period		17,379
Gas Utilities and Infrastructure [Member]
Goodwill [Line Items]
Goodwill, Gross		1,924	1,924
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		1,924
Goodwill, balance at end of period		1,924
Commercial Renewables [Member]
Goodwill [Line Items]
Goodwill, Gross		122	122
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		93
Goodwill, Impaired, Accumulated Impairment Loss		(122)	(29)
Goodwill, Impairment Loss	$ 93	29
Duke Energy Ohio [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		920
Goodwill, Impaired, Accumulated Impairment Loss		(216)	$ (216)
Goodwill, balance at end of period		920
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		596
Goodwill, balance at end of period		596
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		324
Goodwill, balance at end of period		324
Progress Energy [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		3,655
Goodwill, balance at end of period		3,655
Piedmont Natural Gas [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		49
Goodwill, balance at end of period		$ 49