Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Master Credit Facility	Mar. 31, 2021 USD ($)
Line of Credit Facility [Line Items]
Facility size	$ 8,000,000,000
Commercial paper	(3,466,000,000)
Outstanding letters of credit	(31,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	4,422,000,000
Duke Energy Carolinas
Line of Credit Facility [Line Items]
Facility size	1,475,000,000
Commercial paper	(741,000,000)
Outstanding letters of credit	(4,000,000)
Available capacity under the Master Credit Facility	730,000,000
Duke Energy Progress
Line of Credit Facility [Line Items]
Facility size	1,250,000,000
Commercial paper	(292,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity under the Master Credit Facility	956,000,000
Duke Energy Florida
Line of Credit Facility [Line Items]
Facility size	700,000,000
Commercial paper	(243,000,000)
Available capacity under the Master Credit Facility	457,000,000
Duke Energy Ohio
Line of Credit Facility [Line Items]
Facility size	625,000,000
Commercial paper	(259,000,000)
Available capacity under the Master Credit Facility	366,000,000
Duke Energy Indiana
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(150,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	369,000,000
Piedmont
Line of Credit Facility [Line Items]
Facility size	700,000,000
Available capacity under the Master Credit Facility	700,000,000
Duke Energy (Parent) | Proceeds loaned to subsidiary registrants
Line of Credit Facility [Line Items]
Commercial paper	(625,000,000)
Duke Energy (Parent) | Duke Energy (Parent)
Line of Credit Facility [Line Items]
Facility size	2,650,000,000
Commercial paper	(1,781,000,000)
Outstanding letters of credit	(25,000,000)
Available capacity under the Master Credit Facility	$ 844,000,000