Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Master Credit Facility - USD ($)	Sep. 30, 2020	Mar. 31, 2020
Line of Credit Facility [Line Items]
Facility size	$ 8,000,000,000	$ 8,000,000,000
Commercial paper	(2,007,000,000)
Outstanding letters of credit	(40,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	5,872,000,000
Duke Energy Carolinas
Line of Credit Facility [Line Items]
Facility size	1,475,000,000
Commercial paper	(300,000,000)
Outstanding letters of credit	(4,000,000)
Available capacity under the Master Credit Facility	1,171,000,000
Duke Energy Progress
Line of Credit Facility [Line Items]
Facility size	1,250,000,000
Commercial paper	(308,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity under the Master Credit Facility	940,000,000
Duke Energy Florida
Line of Credit Facility [Line Items]
Facility size	800,000,000
Commercial paper	(62,000,000)
Available capacity under the Master Credit Facility	738,000,000
Duke Energy Ohio
Line of Credit Facility [Line Items]
Facility size	625,000,000
Commercial paper	(106,000,000)
Available capacity under the Master Credit Facility	519,000,000
Duke Energy Indiana
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(229,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	290,000,000
Piedmont Natural Gas
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(309,000,000)
Available capacity under the Master Credit Facility	291,000,000
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	(693,000,000)
Outstanding letters of credit	(34,000,000)
Available capacity under the Master Credit Facility	$ 1,923,000,000