Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Allowance for Doubtful Accounts)(Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	$ 17	$ 30	$ 34
Restricted receivables, allowance for doubtful accounts	51	43	44
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	3	3	3
Restricted receivables, allowance for doubtful accounts	6	6	6
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	8	14	16
Restricted receivables, allowance for doubtful accounts	8
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	7	10	9
Restricted receivables, allowance for doubtful accounts	5
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	2	4	7
Restricted receivables, allowance for doubtful accounts	3
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	2	2	2
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	$ 1	$ 1	$ 1