Derivatives and Hedging (Derivative Instruments with Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	$ 82	$ 44
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	82	44
Duke Energy Carolinas [Member]
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	40	19
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	40	19
Progress Energy [Member]
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	42	25
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	42	25
Duke Energy Progress [Member]
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	42	25
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	$ 42	$ 25