Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Master Credit Facility - USD ($)	Sep. 30, 2021	Mar. 31, 2021
Line of Credit Facility [Line Items]
Facility size	$ 8,000,000,000	$ 8,000,000,000
Commercial paper	(1,611,000,000)
Outstanding letters of credit	(31,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	6,277,000,000
Duke Energy Carolinas
Line of Credit Facility [Line Items]
Facility size	1,275,000,000
Commercial paper	(375,000,000)
Outstanding letters of credit	(4,000,000)
Available capacity under the Master Credit Facility	896,000,000
Duke Energy Progress
Line of Credit Facility [Line Items]
Facility size	1,150,000,000
Commercial paper	(253,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity under the Master Credit Facility	895,000,000
Duke Energy Florida
Line of Credit Facility [Line Items]
Facility size	850,000,000
Commercial paper	(527,000,000)
Available capacity under the Master Credit Facility	323,000,000
Duke Energy Ohio
Line of Credit Facility [Line Items]
Facility size	775,000,000
Commercial paper	(419,000,000)
Available capacity under the Master Credit Facility	356,000,000
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
Commercial paper	(276,000,000)
Available capacity under the Master Credit Facility	424,000,000
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	389,000,000
Outstanding letters of credit	(25,000,000)
Available capacity under the Master Credit Facility	$ 3,014,000,000