Goodwill and Intangible Assets (Goodwill By Reportable Operating Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	$ 19,425
Goodwill, Impaired, Accumulated Impairment Loss	(29)
Goodwill, balance at end of period	19,396
Electric Utilities and Infrastructure [Member]
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 [Roll Forward]
Goodwill, balance at beginning of period	1,924
Goodwill, balance at end of period	1,924
Commercial Renewables [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	122
Goodwill, Impaired, Accumulated Impairment Loss	(29)
Goodwill, balance at end of period	93
Goodwill, Impairment Loss	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