Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 3,394
Long-Term Debt	39,931	$ 37,495
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	1,000
Long-Term Debt	8,592	7,711
Duke Energy Progress [Member]
Variable Interest Entities [Line Items]
Long-Term Debt	6,163	6,366
Duke Energy Florida [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	1,294
Long-Term Debt	$ 5,492	4,253
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Dec. 01, 2018
Debt Instrument, Face Amount	$ 325
Long-Term Debt	$ 325	325
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Dec. 01, 2018
Debt Instrument, Face Amount	$ 425
Long-Term Debt	$ 425	425
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Feb. 01, 2019
Debt Instrument, Face Amount	$ 300
Long-Term Debt	$ 300	254
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Apr. 01, 2019
Debt Instrument, Face Amount	$ 225
Long-Term Debt	$ 225	$ 225