Organization and Basis of Presentation (Schedule of Inventory) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Public Utilities, Inventory [Line Items]
Inventory	$ 3,140	$ 3,250
Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	2,283	2,293
Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	515	603
Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	342	354
Duke Energy Carolinas [Member]
Public Utilities, Inventory [Line Items]
Inventory	976	971
Duke Energy Carolinas [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	758	744
Duke Energy Carolinas [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	176	192
Duke Energy Carolinas [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	42	35
Progress Energy [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,473	1,592
Progress Energy [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,071	1,118
Progress Energy [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	187	255
Progress Energy [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	215	219
Duke Energy Progress [Member]
Public Utilities, Inventory [Line Items]
Inventory	956	1,017
Duke Energy Progress [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	748	774
Duke Energy Progress [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	99	139
Duke Energy Progress [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	109	104
Duke Energy Florida [Member]
Public Utilities, Inventory [Line Items]
Inventory	517	574
Duke Energy Florida [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	323	343
Duke Energy Florida [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	88	116
Duke Energy Florida [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	106	115
Duke Energy Ohio [Member]
Public Utilities, Inventory [Line Items]
Inventory	135	133
Duke Energy Ohio [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	87	82
Duke Energy Ohio [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	14	17
Duke Energy Ohio [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	34	34
Duke Energy Indiana [Member]
Public Utilities, Inventory [Line Items]
Inventory	434	450
Duke Energy Indiana [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	294	309
Duke Energy Indiana [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	138	139
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	51	66
Piedmont Natural Gas [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	1	2
Piedmont Natural Gas [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	$ 50	$ 64