Derivatives and Hedging (Derivative Instruments with Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
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	$ 289	$ 845
Fair value of collateral already posted	19	209
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	270	407
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against net derivative positions on the Condensed Consolidated Balance Sheets, payables	19	145
Amounts not offset against net derivative positions		64
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		19
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered		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	262	370
Fair value of collateral already posted	19	23
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	243	347
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against net derivative positions on the Condensed Consolidated Balance Sheets, payables	19	23
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	94	131
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	94	131
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	168	239
Fair value of collateral already posted	19	23
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	149	216
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against net derivative positions on the Condensed Consolidated Balance Sheets, payables	$ 19	23
Duke Energy Ohio [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		456
Fair value of collateral already posted		186
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered		41
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against net derivative positions on the Condensed Consolidated Balance Sheets, payables		122
Amounts not offset against net derivative positions		$ 64