Variable Interest Entities (Schedule of Accounts Receivable Securitizations)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Long-Term debt	$ 45,576	$ 36,842
Duke Energy Carolinas [Member]
Variable Interest Entity [Line Items]
Long-Term debt	9,187	7,711
Duke Energy Progress [Member]
Variable Interest Entity [Line Items]
Long-Term debt	6,409	6,366
Duke Energy Florida [Member]
Variable Interest Entity [Line Items]
Long-Term debt	$ 5,799	4,253
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Dec. 01, 2018
Facility Size	$ 325
Long-Term debt	$ 325	325
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Dec. 01, 2018
Facility Size	$ 425
Long-Term debt	$ 425	425
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Feb. 01, 2019
Facility Size	$ 300
Long-Term debt	$ 300	254
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Apr. 01, 2019
Facility Size	$ 225
Long-Term debt	$ 225	$ 225