Variable Interest Entities (Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 3,394
Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Minimum equity balance required by Cinergy Receivables	3
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 325
Percent of proceeds received as cash	75.00%
Percent of proceeds received as subordinated note	25.00%
Duke American Transmission Company [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	50.00%
Atlantic Coast Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	40.00%
Sabal Trail Transmission Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	7.50%
OVEC [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	9.00%
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 1,000
Duke Energy Carolinas [Member] | DERF [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	425
Duke Energy Progress [Member] | DEPR [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	300
Duke Energy Florida [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	1,294
Duke Energy Florida [Member] | DEFR [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	225
Duke Energy Florida [Member] | DEFPF [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	1,294
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 250
Duke Energy Ohio [Member] | Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 500
Duke Energy Indiana [Member] | Cinergy Receivables [Member]
Variable Interest Entities [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%