Organization and Basis of Presentation (Schedule of Inventory) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Public Utilities, Inventory [Line Items]
Inventory	$ 2,900	$ 3,167
Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	2,317	2,312
Coal
Public Utilities, Inventory [Line Items]
Inventory	312	561
Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	271	294
Duke Energy Carolinas
Public Utilities, Inventory [Line Items]
Inventory	969	1,010
Duke Energy Carolinas | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	779	785
Duke Energy Carolinas | Coal
Public Utilities, Inventory [Line Items]
Inventory	152	186
Duke Energy Carolinas | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	38	39
Progress Energy
Public Utilities, Inventory [Line Items]
Inventory	1,255	1,375
Progress Energy | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	1,009	999
Progress Energy | Coal
Public Utilities, Inventory [Line Items]
Inventory	89	193
Progress Energy | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	157	183
Duke Energy Progress
Public Utilities, Inventory [Line Items]
Inventory	815	911
Duke Energy Progress | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	674	673
Duke Energy Progress | Coal
Public Utilities, Inventory [Line Items]
Inventory	45	131
Duke Energy Progress | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	96	107
Duke Energy Florida
Public Utilities, Inventory [Line Items]
Inventory	439	464
Duke Energy Florida | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	336	325
Duke Energy Florida | Coal
Public Utilities, Inventory [Line Items]
Inventory	43	63
Duke Energy Florida | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	60	76
Duke Energy Ohio
Public Utilities, Inventory [Line Items]
Inventory	114	110
Duke Energy Ohio | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	85	78
Duke Energy Ohio | Coal
Public Utilities, Inventory [Line Items]
Inventory	10	16
Duke Energy Ohio | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	19	16
Duke Energy Indiana
Public Utilities, Inventory [Line Items]
Inventory	367	473
Duke Energy Indiana | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	305	307
Duke Energy Indiana | Coal
Public Utilities, Inventory [Line Items]
Inventory	61	165
Duke Energy Indiana | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	1	1
Piedmont
Public Utilities, Inventory [Line Items]
Inventory	68	68
Piedmont | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	11	12
Piedmont | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	$ 57	$ 56