Derivatives and Hedging (Derivative Instruments That Contain Credit-Risk Related Contingent Features and Cash Collateral) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
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	$ 688	$ 525
Fair value of collateral already posted	202	135
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	86	205
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Payables	116	30
Derivative, collateral, right to reclaim cash - not offset against net derivative	86	122
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	107	168
Fair value of collateral already posted		10
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	107	158
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Payables		10
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	38	60
Fair value of collateral already posted
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	38	60
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	69	108
Fair value of collateral already posted		10
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	69	98
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Payables		10
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	688	355
Fair value of collateral already posted	202	125
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	86	47
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Payables	116	19
Derivative, collateral, right to reclaim cash - not offset against net derivative	$ 86	$ 115