Organization and Basis of Presentation (Schedule of Inventory) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Public Utilities, Inventory [Line Items]
Inventory	$ 3,265	$ 3,522
Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	2,335	2,374
Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	581	774
Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	349	374
Duke Energy Carolinas [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,000	1,055
Duke Energy Carolinas [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	767	767
Duke Energy Carolinas [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	197	251
Duke Energy Carolinas [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	36	37
Progress Energy [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,584	1,717
Progress Energy [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,132	1,167
Progress Energy [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	231	314
Progress Energy [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	221	236
Duke Energy Progress [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,018	1,076
Duke Energy Progress [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	780	813
Duke Energy Progress [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	130	148
Duke Energy Progress [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	108	115
Duke Energy Florida [Member]
Public Utilities, Inventory [Line Items]
Inventory	566	641
Duke Energy Florida [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	351	354
Duke Energy Florida [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	101	166
Duke Energy Florida [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	114	121
Duke Energy Ohio [Member]
Public Utilities, Inventory [Line Items]
Inventory	139	137
Duke Energy Ohio [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	83	84
Duke Energy Ohio [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	17	19
Duke Energy Ohio [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	39	34
Duke Energy Indiana [Member]
Public Utilities, Inventory [Line Items]
Inventory	450	504
Duke Energy Indiana [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	312	312
Duke Energy Indiana [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	136	190
Duke Energy Indiana [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	2	2
Piedmont Natural Gas [Member]
Public Utilities, Inventory [Line Items]
Inventory	53	66
Piedmont Natural Gas [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	2	1
Piedmont Natural Gas [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	$ 51	$ 65