Goodwill (Narrative) (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 19,303,000,000	$ 19,303,000,000
Accumulated impairment charges	122,000,000	122,000,000
Electric Utilities and Infrastructure
Goodwill [Line Items]
Goodwill	17,379,000,000	17,379,000,000
Gas Utilities and Infrastructure
Goodwill [Line Items]
Goodwill	1,924,000,000	1,924,000,000
Duke Energy Ohio
Goodwill [Line Items]
Goodwill	920,000,000	920,000,000
Accumulated impairment charges	216,000,000	216,000,000
Duke Energy Ohio | Electric Utilities and Infrastructure
Goodwill [Line Items]
Goodwill	596,000,000	596,000,000
Duke Energy Ohio | Gas Utilities and Infrastructure
Goodwill [Line Items]
Goodwill	324,000,000	324,000,000
Progress Energy
Goodwill [Line Items]
Goodwill	3,655,000,000	3,655,000,000
Progress Energy | Electric Utilities and Infrastructure
Goodwill [Line Items]
Accumulated impairment charges	0	0
Piedmont
Goodwill [Line Items]
Goodwill	49,000,000	49,000,000
Piedmont | Gas Utilities and Infrastructure
Goodwill [Line Items]
Accumulated impairment charges	$ 0	$ 0