Derivatives and Hedging (Derivative Instruments with Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	$ 96	$ 79
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	96	79
Duke Energy Carolinas
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	45	35
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	45	35
Progress Energy
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	51	44
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	51	44
Duke Energy Progress
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	51	44
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	$ 51	$ 44