Derivatives and Hedging (Derivative Instruments with Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
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	$ 453	$ 334
Fair value of collateral already posted	23	30
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	430	304
Information Regarding Cash Collateral Under Master Netting Arrangements
Amount of right to receive cash collateral, offset against derivative liability	23	30
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	81	45
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	81	45
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	279	290
Fair value of collateral already posted	23	30
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	256	260
Information Regarding Cash Collateral Under Master Netting Arrangements
Amount of right to receive cash collateral, offset against derivative liability	23	30
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	83	93
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	83	93
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	196	194
Fair value of collateral already posted	23	30
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	173	164
Information Regarding Cash Collateral Under Master Netting Arrangements
Amount of right to receive cash collateral, offset against derivative liability	$ 23	$ 30