Fair Value Of Financial Assets And Liabilities (Additional Fair Value Disclosure) (Details) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010
Variable Interest Entity [Member]
Long-term debt, including current maturities	$ 959		$ 976
Book Value [Member]
Long-term debt, including current maturities	19,111	[1]	18,210	[2]
Fair Value [Member]
Long-term debt, including current maturities	$ 21,346		$ 19,484	[2]

[1] Includes Non-recourse long-term debt of variable interest entities of $959 million for Duke Energy and $300 million for Duke Energy Carolinas.

[2] Includes Non-recourse long-term debt of variable interest entities of $976 million for Duke Energy and $300 million for Duke Energy Carolinas.