Organization and Basis of Presentation (Schedule of Inventory) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Public Utilities, Inventory [Line Items]
Inventory	$ 3,190	$ 3,232
Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	2,341	2,297
Coal
Public Utilities, Inventory [Line Items]
Inventory	546	586
Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	303	349
Duke Energy Carolinas
Public Utilities, Inventory [Line Items]
Inventory	992	996
Duke Energy Carolinas | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	779	768
Duke Energy Carolinas | Coal
Public Utilities, Inventory [Line Items]
Inventory	173	187
Duke Energy Carolinas | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	40	41
Progress Energy
Public Utilities, Inventory [Line Items]
Inventory	1,378	1,423
Progress Energy | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	1,021	1,038
Progress Energy | Coal
Public Utilities, Inventory [Line Items]
Inventory	168	186
Progress Energy | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	189	199
Duke Energy Progress
Public Utilities, Inventory [Line Items]
Inventory	910	934
Duke Energy Progress | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	682	686
Duke Energy Progress | Coal
Public Utilities, Inventory [Line Items]
Inventory	120	138
Duke Energy Progress | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	108	110
Duke Energy Florida
Public Utilities, Inventory [Line Items]
Inventory	468	489
Duke Energy Florida | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	340	351
Duke Energy Florida | Coal
Public Utilities, Inventory [Line Items]
Inventory	48	48
Duke Energy Florida | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	80	90
Duke Energy Ohio
Public Utilities, Inventory [Line Items]
Inventory	130	135
Duke Energy Ohio | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	79	79
Duke Energy Ohio | Coal
Public Utilities, Inventory [Line Items]
Inventory	12	15
Duke Energy Ohio | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	39	41
Duke Energy Indiana
Public Utilities, Inventory [Line Items]
Inventory	507	517
Duke Energy Indiana | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	314	318
Duke Energy Indiana | Coal
Public Utilities, Inventory [Line Items]
Inventory	192	198
Duke Energy Indiana | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	1	1
Piedmont Natural Gas
Public Utilities, Inventory [Line Items]
Inventory	47	72
Piedmont Natural Gas | Materials and supplies
Public Utilities, Inventory [Line Items]
Inventory	13	5
Piedmont Natural Gas | Natural gas, oil and other fuel
Public Utilities, Inventory [Line Items]
Inventory	$ 34	$ 67