Organization and Basis of Presentation (Schedule of Inventory) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Public Utilities, Inventory [Line Items]
Inventory	$ 3,149	$ 3,250
Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	2,293	2,293
Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	551	603
Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	305	354
Duke Energy Carolinas [Member]
Public Utilities, Inventory [Line Items]
Inventory	980	971
Duke Energy Carolinas [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	763	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	41	35
Progress Energy [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,537	1,592
Progress Energy [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,095	1,118
Progress Energy [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	221	255
Progress Energy [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	221	219
Duke Energy Progress [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,002	1,017
Duke Energy Progress [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	767	774
Duke Energy Progress [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	125	139
Duke Energy Progress [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	110	104
Duke Energy Florida [Member]
Public Utilities, Inventory [Line Items]
Inventory	535	574
Duke Energy Florida [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	329	343
Duke Energy Florida [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	96	116
Duke Energy Florida [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	110	115
Duke Energy Ohio [Member]
Public Utilities, Inventory [Line Items]
Inventory	108	133
Duke Energy Ohio [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	82	82
Duke Energy Ohio [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	13	17
Duke Energy Ohio [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	13	34
Duke Energy Indiana [Member]
Public Utilities, Inventory [Line Items]
Inventory	453	450
Duke Energy Indiana [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	310	309
Duke Energy Indiana [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	141	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	29	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	$ 28	$ 64