Variable Interest Entities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Variable Interest Entities [Line Items]
Debt instrument, face amount	$ 1,875
Minimum [Member]
Variable Interest Entities [Line Items]
Line of credit facility, expiration date	Dec. 01, 2018
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
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Ownership interest in OVEC	9.00%
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
Debt instrument, face amount	400
Duke Energy Progress [Member]
Variable Interest Entities [Line Items]
Debt instrument, face amount	650
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
Debt instrument, face amount	300
Duke Energy Florida [Member]
Variable Interest Entities [Line Items]
Debt instrument, face amount	225
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
Debt instrument, face amount	$ 225
Duke Energy Ohio [Member] | Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Fixed rate used when selling receivables	1.00%
Duke Energy Indiana [Member] | Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Fixed rate used when selling receivables	1.00%