Variable Interest Entities (Fair Value Assumptions)(Details)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
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	0.60%	0.70%
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	1.20%	1.20%
CRC Receivable Turnover Rate	12.80%	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%	0.30%
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	1.20%	1.20%
CRC Receivable Turnover Rate	10.30%	10.20%