Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entities [Line Items]
Long-Term Debt	$ 53,681	$ 51,123
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Long-Term Debt	10,658	10,633
Duke Energy Progress [Member]
Variable Interest Entities [Line Items]
Long-Term Debt	8,893	7,451
Duke Energy Florida [Member]
Variable Interest Entities [Line Items]
Long-Term Debt	$ 6,795	7,051
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of credit facility, expiration date	Dec. 01, 2020
Facility size	$ 350
Long-Term Debt	350	325
Accounts receivable from securitization	$ 534	564
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, 2020
Facility size	$ 475
Long-Term Debt	475	450
Accounts receivable from securitization	$ 630	699
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, 2021
Facility size	$ 325
Long-Term Debt	325	300
Accounts receivable from securitization	$ 495	547
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, 2021
Facility size	$ 250
Long-Term Debt	250	225
Accounts receivable from securitization	$ 317	$ 357