Variable Interest Entities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Minimum equity balance required by Cinergy Receivables	$ 3
Line of Credit Facility, Expiration Date	Nov. 01, 2016
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Percent of proceeds received as cash	75.00%
Percent of proceeds received as subordinated note	25.00%
Duke Energy Carolinas [Member] | DERF [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Oct. 01, 2016
Duke Energy Progress [Member] | DEPR [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Dec. 01, 2016
Duke Energy Florida [Member] | DEFR [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Mar. 01, 2017
Duke Energy Ohio [Member] | Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%
Duke Energy Ohio [Member] | Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Ownership interest in OVEC	9.00%
Duke Energy Indiana [Member] | Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%