Commitments and Contingencies (Narrative) (Details) (USD $)	9 Months Ended		0 Months Ended		9 Months Ended					0 Months Ended	1 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2014 Brazil Expansion Lawsuit [Member]	Sep. 30, 2014 Duke Energy Carolinas [Member] North Carolina Ash Basins [Member] Dan River [Member]	Feb. 21, 2014 Duke Energy Carolinas [Member] North Carolina Ash Basins [Member] Minimum [Member] Dan River [Member] gal T	Feb. 21, 2014 Duke Energy Carolinas [Member] North Carolina Ash Basins [Member] Maximum [Member] Dan River [Member] T gal	Sep. 30, 2014 Duke Energy Carolinas [Member] New Source Review Provisions Of Clean Air Act [Member] Claims plant project	Sep. 30, 2014 Duke Energy Carolinas [Member] Asbestos Issue [Member]	Dec. 31, 2013 Duke Energy Carolinas [Member] Asbestos Issue [Member]	Sep. 30, 2014 Duke Energy Carolinas [Member] Asbestos Issue [Member] Malignant Asbestos Claim [Member] Claims	Sep. 30, 2014 Duke Energy Carolinas [Member] Asbestos Issue [Member] Non Malignant Asbestos Claim [Member] Claims	Oct. 03, 2012 Progress Energy [Member] Synthetic Fuels [Member]	Dec. 31, 2009 Progress Energy [Member] Synthetic Fuels [Member]	Dec. 31, 2012 Progress Energy [Member] Synthetic Fuels [Member]	Sep. 30, 2014 Duke Energy Progress [Member] Spent Nuclear Fuels [Member]	Sep. 30, 2014 Duke Energy Florida [Member] Spent Nuclear Fuels [Member]	Mar. 31, 2014 Duke Energy Florida [Member] Westinghouse Electric Company Litigation [Member]	Mar. 28, 2014 Duke Energy Florida [Member] Westinghouse Electric Company Litigation [Member]	Dec. 11, 2012 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member]
Valuation and Qualifying Accounts [Abstract]
Coal ash released, in tons			30,000	39,000
Basin water released, in gallons			24,000,000	27,000,000
Environmental remediation expense		$ 20,000,000
Obligation to expand installed generation capacity, percent	15.00%
Maximum civil penalties per day for each violation					37,500
Projects with Alleged NSR Violations					29
Number of Coal Plants with Alleged NSR Violations					25
Number of Retired Plants					11
Loss contingency, pending claims, number					13			23	61
Remaining Number of Coal Plants with Alleged NSR Violations					13
Asbestos-related injuries and damages reserves						591,000,000	616,000,000	7,000,000	13,000,000
Reinsurance retention policy, amount retained						476,000,000
Reinsurance retention policy, excess retention, amount reinsured						864,000,000
Probable insurance recoveries						616,000,000	649,000,000
Loss contingency, damages paid, value											154,000,000
Damages awarded to plaintiff										90,000,000
Gain recognized in period												63,000,000
Gain (Loss) Related to Litigation Settlement													83,000,000	21,000,000
Loss contingency, damages sought, value															510,000,000
Gain contingency, unrecorded amount																$ 54,000,000	$ 560,000,000