Commitments and Contingencies (Narrative) (Details) $ in Millions						1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
	Feb. 08, 2016 USD ($)	Mar. 10, 2015 USD ($)	Feb. 02, 2014 T gal	Aug. 10, 2011	Aug. 09, 2011	Mar. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) plant Claims basin	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Aug. 18, 2014 gal
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual								$ 110.0		$ 166.0
Charge for settlement agreement							$ 46.0		$ 53.0
Coal Ash Act Intermediate Ranking [Member]
Valuation and Qualifying Accounts [Abstract]
Number of Ash Basins | basin								12
Number of Plants with Ash Basins | plant								4
Coal Ash Act Low Ranking [Member]
Valuation and Qualifying Accounts [Abstract]
Number of Ash Basins | basin								4
Number of Plants with Ash Basins | plant								3
Coal Ash Act Low to Intermediate Ranking [Member]
Valuation and Qualifying Accounts [Abstract]
Number of Ash Basins | basin								9
Number of Plants with Ash Basins | plant								6
NCDEQ State Enforcement Actions [Member]
Valuation and Qualifying Accounts [Abstract]
Number of Plants with No Disputed Facts | plant								7
Number of Plants with Ash Basins | plant								14
Potential Groundwater Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Number of Plants with Ash Basins | plant								14
Brazil Expansion Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Obligation to expand installed generation capacity, percent				15.00%	15.00%
Antitrust Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement, Expense							71.0		81.0
Duke Energy Carolinas [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual								$ 14.0		11.0
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Civil Penalty Assessed	$ 6.8
Duke Energy Carolinas [Member] | Groundwater Violation [Member]
Valuation and Qualifying Accounts [Abstract]
Charge for settlement agreement								1.0
Duke Energy Carolinas [Member] | Asbestos Issue [Member]
Valuation and Qualifying Accounts [Abstract]
Asbestos-related injuries and damages reserves								515.0		536.0
Reinsurance retention policy, excess retention, amount reinsured								847.0
Probable insurance recoveries								$ 600.0		599.0
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Non Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims								89
Asbestos-related injuries and damages reserves								$ 24.0
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims								83
Asbestos-related injuries and damages reserves								$ 15.0
Duke Energy Carolinas [Member] | Minimum [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Coal ash released, in tons | T			30,000
Basin water released, in gallons | gal			24,000,000
Duke Energy Carolinas [Member] | Maximum [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Coal ash released, in tons | T			39,000
Basin water released, in gallons | gal			27,000,000
Progress Energy [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual								52.0		54.0
Duke Energy Progress [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual								6.0		6.0
Duke Energy Progress [Member] | North Carolina Ash Basins [Member] | L V Sutton Plant [Member]
Valuation and Qualifying Accounts [Abstract]
Civil Penalty Assessed		$ 25.0
Duke Energy Progress [Member] | Groundwater Violation [Member]
Valuation and Qualifying Accounts [Abstract]
Charge for settlement agreement								6.0
Duke Energy Progress [Member] | Groundwater Violation [Member] | L V Sutton Plant [Member]
Valuation and Qualifying Accounts [Abstract]
Civil Penalty Assessed		$ 25.0
Duke Energy Florida [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual								30.0		31.0
Duke Energy Florida [Member] | Westinghouse Electric Company Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount								54.0
Loss contingency, damages sought, value						$ 510.0
Duke Energy Ohio [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual								$ 4.0		80.0
Duke Energy Ohio [Member] | W.C. Beckjord Station [Member]
Valuation and Qualifying Accounts [Abstract]
Gallons of Fuel Released | gal											9,000
Duke Energy Ohio [Member] | Antitrust Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement Amount										$ 81.0
Litigation Settlement, Expense							$ 71.0		$ 81.0