Commitments and Contingencies (Narrative) (Details) gal in Millions					12 Months Ended
	Sep. 23, 2016 USD ($)	Feb. 08, 2016 USD ($)	Apr. 22, 2015 USD ($)	Mar. 10, 2015 USD ($)	Dec. 31, 2017 USD ($) plant Claims reactor T	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2014 USD ($)	Feb. 28, 2014 gal T
Insurance [Abstract]
Insured public liability limit per nuclear incident					$ 13,400,000,000
Excess nuclear liability program coverage					13,000,000,000
Pro rata assessment for each reactor owned for each incident exceeding public liability insurance					$ 127,000,000
Number of licensed nuclear reactors | reactor					102
Annual payment limit to pro rata assessments					$ 19,000,000
Industry aggregate limit					3,200,000,000
Sublimit for non-nuclear terrorist events					$ 1,830,000,000
Insurance Coverage Percentage Initial Weeks					100.00%
Accidental Outage Insurance Coverage Initial Weeks					365 days
Insurance Coverage Percentage Additional Weeks					80.00%
Accidental Outage Insurance Coverage Additional Weeks					770 days
Weeks of Sublimits for Accidental Outage Coverage					728 days
Sublimit accidental outage recovery					$ 328,000,000
Maximum Magnitude of Retroactive Premiums					10
Maximum Period for Retroactive Premium Assessment					6 years
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					$ 88,000,000		$ 98,000,000
Progress Energy Merger Shareholder Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Payments for Legal Settlements			$ 25,000,000
Litigation Settlement Covered by Insurance			$ 121,000,000
Proceeds from Legal Settlements					$ 20,000,000
Litigation Settlement, Amount Awarded to Other Party				$ 146,000,000
Coal Ash Insurance Coverage Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Number of NC and SC Plants with Ash Basins | plant					15
NCDEQ State Enforcement Actions [Member]
Valuation and Qualifying Accounts [Abstract]
Facilities with Ash Basins | plant					14
Number of Plants with No Disputed Facts | plant					7
Number of Plants with Disputed Facts | plant					7
Groundwater Contamination Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Goodwill Payment					$ 5,000
Water Bill Stipend Period					25 years
Duke Energy Carolinas [Member]
Insurance [Abstract]
Primary nuclear liability program coverage					$ 450,000,000
Max Retroactive Premium Assessments					146,000,000
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					30,000,000		23,000,000
Duke Energy Carolinas [Member] | McGuire Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses					1,500,000,000
Additional nuclear accident limit					1,250,000,000
Accidental outage insurance coverage policy limit					490,000,000
Duke Energy Carolinas [Member] | Catawba Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses					1,500,000,000
Dedicated additional nuclear accident limit					1,250,000,000
Additional Non Nuclear Accident Limit					750,000,000
Accidental outage insurance coverage policy limit					$ 490,000,000
Potential Obligation percentage					100.00%
Duke Energy Carolinas [Member] | Oconee Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses					$ 1,500,000,000
Additional nuclear accident limit					1,250,000,000
Additional Non Nuclear Accident Limit					750,000,000
Accidental outage insurance coverage policy limit					434,000,000
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Civil Penalty Assessed		$ 6,800,000
Litigation Settlement, Amount Awarded to Other Party	$ 6,000,000
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member] | Minimum [Member]
Valuation and Qualifying Accounts [Abstract]
Estimated amount of ash released, in tons | T									30,000
Estimated amount of ash basin water released, in gallons | gal									24
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member] | Maximum [Member]
Valuation and Qualifying Accounts [Abstract]
Estimated amount of ash released, in tons | T									39,000
Estimated amount of ash basin water released, in gallons | gal									27
Duke Energy Carolinas [Member] | Groundwater Contamination Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					19,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member]
Valuation and Qualifying Accounts [Abstract]
Asbestos-related injuries and damages reserves					489,000,000		512,000,000
Reinsurance retention policy, excess retention, amount reinsured					797,000,000
Probable insurance recoveries					$ 585,000,000		587,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Non Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims					161
Asbestos-related injuries and damages reserves					$ 42,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims					54
Asbestos-related injuries and damages reserves					$ 16,000,000
Progress Energy [Member]
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					55,000,000		59,000,000
Duke Energy Progress [Member]
Insurance [Abstract]
Primary nuclear liability program coverage					450,000,000
Max Retroactive Premium Assessments					96,000,000
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					13,000,000		14,000,000
Duke Energy Progress [Member] | Robinson Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses					1,500,000,000
Additional nuclear accident limit					1,250,000,000
Accidental outage insurance coverage policy limit					378,000,000
Duke Energy Progress [Member] | Brunswick Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses					1,500,000,000
Additional nuclear accident limit					1,250,000,000
Accidental outage insurance coverage policy limit					462,000,000
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses					1,500,000,000
Additional nuclear accident limit					1,250,000,000
Accidental outage insurance coverage policy limit					448,000,000
Duke Energy Progress [Member] | Groundwater Contamination Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					4,000,000
Duke Energy Progress [Member] | Spent Nuclear Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount					48,000,000
Litigation Settlement, Amount Awarded from Other Party					$ 48,000,000
Duke Energy Progress [Member] | Gypsum Supply Agreements [Member]
Valuation and Qualifying Accounts [Abstract]
Minimum Amount of Gypsum To Be Supplied | T					50,000
Duke Energy Florida [Member]
Insurance [Abstract]
Primary nuclear liability program coverage					$ 450,000,000
Max Retroactive Premium Assessments					1,000,000
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					24,000,000		28,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member]
Insurance [Abstract]
Sublimit property damage losses					50,000,000
Duke Energy Florida [Member] | Spent Nuclear Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount					25,000,000
Litigation Settlement, Amount Awarded from Other Party					21,000,000
Duke Energy Florida [Member] | Westinghouse Electric Company Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount					54,000,000
Loss Contingency, Damages Sought, Original Amount					482,000,000			$ 510,000,000
Loss Contingency, Damages Awarded, Value					30,000,000
Gain Contingency, Dismissed Amount					54,000,000
Loss contingency, damages sought, value					424,000,000
Loss Contingency Damages Awarded and Interest, Value					34,000,000
Duke Energy Florida [Member] | MGP Cost Recovery Action [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, damages sought, value					43,000,000
Duke Energy Ohio [Member]
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters							4,000,000
Duke Energy Ohio [Member] | Antitrust Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement, Amount Awarded to Other Party						$ 81,000,000
Litigation Settlement, Expense						$ 81,000,000
Piedmont Natural Gas [Member]
Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters					$ 2,000,000		$ 2,000,000