Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details)	Sep. 30, 2015 USD ($)
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 1,700,000,000
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	500,000,000
Duke Energy Progress [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	1,200,000,000
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