Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Line of Credit Facility [Line Items]
Tax-exempt bonds	$ (477,000,000)	$ (730,000,000)
Duke Energy Carolinas
Line of Credit Facility [Line Items]
Tax-exempt bonds		(243,000,000)
Duke Energy Progress
Line of Credit Facility [Line Items]
Tax-exempt bonds	(48,000,000)	(48,000,000)
Duke Energy Ohio
Line of Credit Facility [Line Items]
Tax-exempt bonds	(77,000,000)	(77,000,000)
Duke Energy Indiana
Line of Credit Facility [Line Items]
Tax-exempt bonds	(352,000,000)	$ (362,000,000)
Revolving Credit Facility
Line of Credit Facility [Line Items]
Facility size	8,000,000,000		$ 8,000,000,000
Commercial paper	(2,239,000,000)
Outstanding letters of credit	(40,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity	5,640,000,000
Revolving Credit Facility | Parent Company
Line of Credit Facility [Line Items]
Facility size	2,650,000,000
Outstanding letters of credit	(34,000,000)
Available capacity	2,616,000,000
Revolving Credit Facility | Duke Energy Carolinas
Line of Credit Facility [Line Items]
Facility size	1,475,000,000
Commercial paper	(736,000,000)
Outstanding letters of credit	(4,000,000)
Available capacity	735,000,000
Revolving Credit Facility | Duke Energy Progress
Line of Credit Facility [Line Items]
Facility size	1,250,000,000
Commercial paper	(407,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity	841,000,000
Revolving Credit Facility | Duke Energy Florida
Line of Credit Facility [Line Items]
Facility size	800,000,000
Commercial paper	(179,000,000)
Available capacity	621,000,000
Revolving Credit Facility | Duke Energy Ohio
Line of Credit Facility [Line Items]
Facility size	625,000,000
Commercial paper	(176,000,000)
Available capacity	449,000,000
Revolving Credit Facility | Duke Energy Indiana
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(257,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity	262,000,000
Revolving Credit Facility | Piedmont
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(484,000,000)
Available capacity	116,000,000
Proceeds Loaned To Subsidiary Registrants | Revolving Credit Facility | Parent Company
Line of Credit Facility [Line Items]
Commercial paper	$ (625,000,000)