Debt And Credit Facilities (Narrative) (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Credit facility, outstanding balance	$ 6,000,000,000
Debt to total capitalization percentage, for each borrower	65
Current maturities of long-term debt	1,870,000,000	1,894,000,000
Duke Energy Corp [Member]
Notes fixed interest rate	5.65%
Demand notes, maximum amount available for sale	500,000,000
Equity method investment, ownership percentage sale		25.00%
Investment balance		64,000,000
Investment balance, debt obligations		64,000,000
Proceeds from sales of notes	209,000,000	79,000,000
Current maturities of long-term debt	250,000,000
Debt Instrument, Maturity Date	Jun. 01, 2013
Duke Energy Indiana [Member]
Debt to total capitalization percentage, for each borrower	65
Current maturities of long-term debt	5,000,000	6,000,000
Duke Energy Ohio [Member]
Debt to total capitalization percentage, for each borrower	65
Current maturities of long-term debt	757,000,000	507,000,000
Duke Energy Carolinas [Member]
Debt to total capitalization percentage, for each borrower	65
Current maturities of long-term debt	427,000,000	1,178,000,000
Duke Energy Master Credit Facility expiring in November 2016 [Member]
Available Capacity	4,000,000,000
Conditional capacity	2,000,000,000
First Mortgage Bonds [Member] | Duke Energy Indiana [Member]
Notes fixed interest rate	4.20%
Debt Instrument, Maturity Date	Mar. 15, 2042
Debt Instrument, Issuance Date	March 2012
Debt Instrument, Face Amount	250,000,000
First Mortgage Bonds [Member] | Duke Energy Ohio [Member]
Notes fixed interest rate	2.10%
Current maturities of long-term debt	250,000,000
Debt Instrument, Maturity Date	Jun. 01, 2013
First Mortgage Bonds [Member] | Duke Energy Carolinas [Member]
Debt Instrument, Issuance Date	December 2011
Debt Instrument, Face Amount	1,000,000,000
Unsecured Notes [Member] | Duke Energy Ohio [Member]
Notes fixed interest rate	5.70%
Current maturities of long-term debt	500,000,000	500,000,000
Debt Instrument, Maturity Date	Sep. 01, 2012
Unsecured Notes [Member] | Duke Energy Carolinas [Member]
Notes fixed interest rate	6.25%	5.625%
Current maturities of long-term debt	400,000,000	400,000,000
Debt Instrument, Maturity Date	Jan. 15, 2012	Nov. 01, 2012
Debt Instrument, Face Amount	750,000,000
CRC Credit Facility [Member]
Credit facility, outstanding balance	$ 269,000,000	$ 273,000,000
Line of Credit Facility, Expiration Date	October 2012