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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