Variable Interest Entities (Fair Value Assumptions)(Details) (Variable Interest Entity, Not Primary Beneficiary [Member], Cinergy Receivables [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Anticipated credit loss ratio	0.60%	0.60%
Discount rate	1.20%	1.20%
Receivable turnover rate	12.80%	12.80%
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Anticipated credit loss ratio	0.30%	0.30%
Discount rate	1.20%	1.20%
Receivable turnover rate	10.50%	10.30%