Variable Interest Entities (Receivables Sold)(Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Duke Energy Ohio [Member]
CRC Gross Receivables Sold	$ 251	$ 302
CRC Retained Interests	102	129
CRC Net Receivables Sold	149	173
Duke Energy Indiana [Member]
CRC Gross Receivables Sold	307	279
CRC Retained Interests	143	139
CRC Net Receivables Sold	$ 164	$ 140