Commitments and Contingencies (Narrative) (Details) gal in Millions	1 Months Ended	6 Months Ended
	Feb. 28, 2014 T gal	Jun. 30, 2017 USD ($) plant claim	Dec. 31, 2016 USD ($)	Mar. 31, 2014 USD ($)
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		$ 82,000,000	$ 98,000,000
Progress Energy Merger Shareholder Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount		$ 27,000,000
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]
Number of Plants with No Disputed Facts | plant		7
Number of NC Plants with Ash Basins | plant		14
Number of Plants with Disputed Facts | plant		7
Potential Groundwater Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Number of NC Plants with Ash Basins | plant		14
Goodwill Payment		$ 5,000
Water Bill Stipend Period		25 years
Duke Energy Carolinas [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		$ 23,000,000	23,000,000
Duke Energy Carolinas [Member] | Potential Groundwater Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		18,000,000
Duke Energy Carolinas [Member] | Asbestos-related Injuries and Damages Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Asbestos-related injuries and damages reserves		497,000,000	512,000,000
Reinsurance retention policy, excess retention, amount reinsured		814,000,000
Probable insurance recoveries		$ 587,000,000	587,000,000
Duke Energy Carolinas [Member] | Asbestos-related Injuries and Damages Claims [Member] | Non-Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | claim		87
Asbestos-related injuries and damages reserves		$ 23,000,000
Duke Energy Carolinas [Member] | Asbestos-related Injuries and Damages Claims [Member] | Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | claim		58
Asbestos-related injuries and damages reserves		$ 16,000,000
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
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
Progress Energy [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		57,000,000	59,000,000
Duke Energy Progress [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		12,000,000	14,000,000
Duke Energy Progress [Member] | Potential Groundwater Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		4,000,000
Duke Energy Florida [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		28,000,000	28,000,000
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]
Gain contingency, unrecorded amount		43,000,000
Duke Energy Ohio [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual			$ 4,000,000
Duke Energy Indiana [Member] | Benton County Wind Farm Dispute [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, damages sought, value		16,000,000
Litigation Settlement, Amount Awarded to Other Party		$ 29,000,000