Variable Interest Entities (Fair Value Assumptions)(Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Cinergy Receivables [Member]	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Anticipated credit loss ratio	0.50%	0.50%
Discount rate	1.90%	1.50%
Receivable turnover rate	13.40%	13.30%
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Anticipated credit loss ratio	0.30%	0.30%
Discount rate	1.90%	1.50%
Receivable turnover rate	10.70%	10.60%