Variable Interest Entities (Receivables Sold)(Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Duke Energy Ohio [Member]
CRC Gross Receivables Sold	$ 241	$ 302
CRC Retained Interests	85	129
CRC Net Receivables Sold	156	173
Duke Energy Indiana [Member]
CRC Gross Receivables Sold	282	279
CRC Retained Interests	118	139
CRC Net Receivables Sold	$ 164	$ 140