Variable Interest Entities (Fair Value Assumptions)(Details) (Cinergy Receivables [Member])	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Anticipated credit loss ratio	0.60%	0.70%
Discount rate	1.20%	1.20%
Receivable turnover rate	12.80%	12.70%
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	10.30%	10.20%