Commitments and Contingencies (Details) (USD $)	0 Months Ended		1 Months Ended		3 Months Ended	12 Months Ended				60 Months Ended						6 Months Ended
	Sep. 03, 2010	Jun. 30, 2009	Jul. 31, 2010 gal	Sep. 30, 2008	Mar. 31, 2009	Dec. 31, 2009	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Reserve for Environmental Costs [Member]	Dec. 31, 2015 Duke Energy Carolinas [Member] Coal Combustion Product Management [Member]	Dec. 31, 2015 Duke Energy Ohio [Member] Coal Combustion Product Management [Member]	Dec. 31, 2015 Duke Energy Indiana [Member] Coal Combustion Product Management [Member]	Dec. 31, 2015 Coal Combustion Product Management [Member]	Jun. 30, 2011 Litigation and Legal Proceedings [Member]	Dec. 31, 2010 Litigation and Legal Proceedings [Member]	Jun. 30, 2011 Federal Advance Clean Coal Tax Credits Associated With Its Construction Of Cliffside Unit6 [Member]	Jun. 30, 2011 Federal Advance Clean Coal Tax Credits Associated With Its Construction Of Edwardsport Igcc Plant [Member]
Additional electric transmission fine assessed					$ 11,000,000
Pre-tax charge recorded associated with the resolutions						33,000,000
Alleged amount borrowed from a consortium of banks	1,200,000,000
Litigation settlement, gross				150,000,000
Environmental exit costs, anticipated cost										131,000,000	70,000,000	168,000,000	369,000,000
Aquatic protection requirements for existing facilities, in gallons			2,000,000
Remediation reserve									47,000,000
DEIGP electric transmission charges promulgated by ANEEL		69,000,000
Probable insurance recoveries							850,000,000	850,000,000
Investment tax credit																125,000,000	134,000,000
Related injuries and damages claims														$ 840,000,000	$ 900,000,000