Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details) (USD $)	Mar. 31, 2015
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 500,000,000
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	500,000,000
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	400,000,000
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	300,000,000
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 225,000,000