Variable Interest Entities (Fair Value Assumptions)(Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Expected Credit Losses	0.70%	0.80%
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	1.20%	2.60%
CRC Receivable Turnover Rate	12.70%	12.70%
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Expected Credit Losses	0.30%	0.40%
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	1.20%	2.60%
CRC Receivable Turnover Rate	10.20%	10.20%