Derivatives and Hedging (Derivative Instruments with Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
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	$ 34
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	40	34
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	14	16
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	14	16
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	25	18
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	25	18
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	9	6
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	9	6
Duke Energy Florida [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	17	12
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	$ 17	$ 12