Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 1,000
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	1,000
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 425
Line of Credit Facility, Expiration Date	Dec. 01, 2018
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 300
Line of Credit Facility, Expiration Date	Feb. 01, 2019
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 225
Line of Credit Facility, Expiration Date	Apr. 01, 2019