Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Long-Term debt	$ 51,123	$ 49,035
Duke Energy Carolinas [Member]
Variable Interest Entity [Line Items]
Long-Term debt	10,633	8,598
Duke Energy Progress [Member]
Variable Interest Entity [Line Items]
Long-Term debt	7,451	7,204
Duke Energy Florida [Member]
Variable Interest Entity [Line Items]
Long-Term debt	$ 7,051	6,327
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Dec. 01, 2020
Facility Size	$ 325
Long-Term debt	325	325
Restricted Receivables	$ 564	545
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, 2020
Facility Size	$ 450
Long-Term debt	450	450
Restricted Receivables	$ 699	640
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, 2021
Facility Size	$ 300
Long-Term debt	300	300
Restricted Receivables	$ 547	459
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, 2021
Facility Size	$ 225
Long-Term debt	225	225
Restricted Receivables	$ 357	$ 317