Commitments and Contingencies (Narrative) (Details) gal in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Feb. 28, 2014 T gal	Sep. 30, 2017 USD ($) plant claim	Sep. 30, 2017 USD ($) plant claim	Dec. 31, 2016 USD ($)	Mar. 31, 2014 USD ($)
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		$ 83,000,000	$ 83,000,000	$ 98,000,000
Progress Energy Merger Shareholder Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Proceeds from Legal Settlements		$ 20,000,000
Coal Ash Insurance Coverage Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Number of NC and SC Plants with Ash Basins | plant		15	15
NCDEQ State Enforcement Actions [Member]
Valuation and Qualifying Accounts [Abstract]
Number of Plants with No Disputed Facts | plant		7	7
Number of NC Plants with Ash Basins | plant		14	14
Number of Plants with Disputed Facts | plant		7	7
Groundwater Contamination Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Goodwill Payment		$ 5,000	$ 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	23,000,000
Duke Energy Carolinas [Member] | Groundwater Contamination Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		19,000,000	19,000,000
Duke Energy Carolinas [Member] | Asbestos-related Injuries and Damages Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Asbestos-related injuries and damages reserves		486,000,000	486,000,000	512,000,000
Reinsurance retention policy, excess retention, amount reinsured			797,000,000
Probable insurance recoveries		$ 570,000,000	$ 570,000,000	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		120	120
Asbestos-related injuries and damages reserves		$ 29,000,000	$ 29,000,000
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		57	57
Asbestos-related injuries and damages reserves		$ 16,000,000	$ 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		56,000,000	56,000,000	59,000,000
Duke Energy Progress [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		13,000,000	13,000,000	14,000,000
Duke Energy Progress [Member] | Groundwater Contamination Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		4,000,000	4,000,000
Duke Energy Florida [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		28,000,000	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	54,000,000
Loss Contingency, Damages Sought, Original Amount		482,000,000	482,000,000		$ 510,000,000
Loss Contingency, Damages Awarded, Value			30,000,000
Gain Contingency, Dismissed Amount		54,000,000	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	$ 43,000,000
Duke Energy Ohio [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual				$ 4,000,000