Variable Interest Entities (Fair Value Assumptions)(Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Duke Energy Ohio [Member]
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Expected Credit Losses	0.80%	0.80%
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	1.30%	2.60%
CRC Receivable Turnover Rate	12.70%	12.70%
Duke Energy Indiana [Member]
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Expected Credit Losses	0.40%	0.40%
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	1.30%	2.60%
CRC Receivable Turnover Rate	10.20%	10.20%