Derivatives and Hedging (Derivative Instruments That Contain Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	$ 44	$ 59
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	44	59
Duke Energy Carolinas [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	19	35
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	19	35
Progress Energy [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	25	25
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	25	25
Duke Energy Progress [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	25	15
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	$ 25	15
Duke Energy Florida [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position		10
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered		$ 10