Risk Management, Derivative Instruments And Hedging Activities (Information Regarding Cash Collateral Under Master Netting Arrangements) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Derivative [Line Items]
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Receivables	$ 73		$ 10
Derivative, Collateral, Obligation to Return Cash - not offset against net derivative	93		30
Duke Energy Carolinas [Member]
Derivative [Line Items]
Derivative, Collateral, Obligation to Return Cash - not offset against net derivative	105	[1]	94	[1]
Progress Energy [Member]
Derivative [Line Items]
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Receivables	58		140
Derivative, Collateral, Obligation to Return Cash - not offset against net derivative	1		3
Progress Energy Carolinas [Member]
Derivative [Line Items]
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Receivables	9		23
Progress Energy Florida [Member]
Derivative [Line Items]
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Receivables	49		117
Derivative, Collateral, Obligation to Return Cash - not offset against net derivative	1		3
Duke Energy Ohio [Member]
Derivative [Line Items]
Amounts offset against derivative positions on the net condensed Consolidated Balance Sheets, Receivables	15		9
Derivative, Collateral, Obligation to Return Cash - not offset against net derivative	$ 92		$ 28

[1] Does not exceed 5% of Total current assets or Total current liabilities at December 31, 2011.