Variable Interest Entities (Fair Value Assumptions)(Details) - Cinergy Receivables [Member]	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Anticipated credit loss ratio	0.60%	0.60%
Discount rate	1.40%	1.20%
Receivable turnover rate	13.20%	12.90%
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Anticipated credit loss ratio	0.30%	0.30%
Discount rate	1.40%	1.20%
Receivable turnover rate	10.60%	10.60%