Debt and Credit Facilities (Narrative) (Details) (USD $)	1 Months Ended			9 Months Ended	12 Months Ended							9 Months Ended					9 Months Ended									9 Months Ended	12 Months Ended	9 Months Ended
	Aug. 31, 2014	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Duke Energy Corp [Member]	Dec. 31, 2011 Duke Energy Corp [Member]	Sep. 30, 2012 Duke Energy Indiana [Member]	Jun. 30, 2012 Duke Energy Indiana [Member]	Dec. 31, 2011 Duke Energy Indiana [Member]	Sep. 30, 2012 Duke Energy Ohio [Member]	Jun. 30, 2012 Duke Energy Ohio [Member]	Dec. 31, 2011 Duke Energy Ohio [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member]	Jun. 30, 2012 Duke Energy Carolinas [Member]	Dec. 31, 2011 Duke Energy Carolinas [Member]	Sep. 30, 2012 Duke Energy Master Credit Facility expiring in November 2016 [Member]	Sep. 30, 2012 Duke Energy Master Credit Facility Expiring in November 2017 [Member]	Sep. 30, 2012 First Mortgage Bonds [Member] Duke Energy Indiana [Member]	Sep. 30, 2012 First Mortgage Bonds [Member] Duke Energy Ohio [Member]	Sep. 30, 2012 First Mortgage Bonds [Member] Duke Energy Carolinas [Member]	Sep. 30, 2012 First Mortgage Bonds [Member] Progress Energy Carolinas [Member]	Sep. 30, 2012 First Mortgage Bonds [Member] Progress Energy Florida [Member]	Sep. 30, 2012 Unsecured Notes [Member] Duke Energy Corp [Member]	Sep. 30, 2012 Unsecured Notes [Member] Duke Energy Indiana [Member]	Sep. 30, 2012 Unsecured Notes [Member] Duke Energy Carolinas [Member]	Dec. 31, 2011 Unsecured Notes [Member] Duke Energy Carolinas [Member]	Sep. 30, 2012 CRC Credit Facility [Member]	Dec. 31, 2011 CRC Credit Facility [Member]	Sep. 30, 2012 Senior Unsecured Notes Expiring August 15, 2017 [Member] Duke Energy Corp [Member]	Dec. 31, 2011 First Mortgage Bonds Prior Year Issuance [Member] Duke Energy Carolinas [Member]
Debt Instrument, Interest Rate, Stated Percentage				5.65%													4.20%	2.10%	400.00%	512.50%	480.00%	305.00%	512.50%	6.25%	5.625%			162.50%
Proceeds from sales of notes				$ 288	$ 79,000,000
Credit facility, outstanding balance																										275,000,000	273,000,000
Available Capacity															4,000,000,000
Conditional capacity															2,000,000,000
Debt to total capitalization percentage, for each borrower		65					65			65			65
Current maturities of long-term debt		2,488,000,000	1,894,000,000	250,000,000		404,000,000		6,000,000	261,000,000		507,000,000	427,000,000		1,178,000,000				250,000,000		400,000,000	425,000,000		400,000,000	400,000,000	400,000,000
Debt Instrument, Maturity Date				Jun. 01, 2013								Jan. 15, 2012					Mar. 15, 2042	Jun. 01, 2013	Sep. 01, 2042	Sep. 01, 2013	Mar. 01, 2013	Aug. 15, 2022	Sep. 01, 2013	Nov. 01, 2012				Aug. 15, 2017
Debt Instrument, Issuance Date																	March 2012		December 2011 Septebmer 2012			August 2012
Debt Instrument, Face Amount																	250,000,000		650,000,000			500,000,000		750,000,000				700,000,000	1,000,000,000
Line of Credit Facility, Expiration Date	August 2014
Line of Credit Facility, Maximum Borrowing Capacity																$ 5,630,000,000