v2.4.0.8
Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) (USD $)
In Millions, unless otherwise specified
 9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Environmental Matters Details [Line Items]    
Environmental Exit Costs, Reasonably Possible Additional Loss $ 83  
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning balance 79 75
Provisions/Adjustments 34 6
Cash reductions (8) (17)
Ending balance 105 64
Duke Energy Carolinas [Member]
    
Environmental Matters Details [Line Items]    
Environmental Exit Costs, Reasonably Possible Additional Loss 25  
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning balance 11 12
Provisions/Adjustments (1)   
Cash reductions      
Ending balance 10 12
Progress Energy [Member]
    
Environmental Matters Details [Line Items]    
Environmental Exit Costs, Reasonably Possible Additional Loss 9  
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning balance 27 33
Provisions/Adjustments 4 5
Cash reductions (6) (6)
Ending balance 25 32
Duke Energy Progress [Member]
    
Environmental Matters Details [Line Items]    
Environmental Exit Costs, Reasonably Possible Additional Loss 2  
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning balance 8 14
Provisions/Adjustments 3 1
Cash reductions (4) (2)
Ending balance 7 13
Duke Energy Florida [Member]
    
Environmental Matters Details [Line Items]    
Environmental Exit Costs, Reasonably Possible Additional Loss 7  
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning balance 19 19
Provisions/Adjustments 1 4
Cash reductions (2) (4)
Ending balance 18 19
Duke Energy Ohio [Member]
    
Environmental Matters Details [Line Items]    
Environmental Exit Costs, Reasonably Possible Additional Loss 42  
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning balance 27 15
Provisions/Adjustments 28 (1)
Cash reductions (1) (8)
Ending balance 54 6
Duke Energy Indiana [Member]
    
Environmental Matters Details [Line Items]    
Environmental Exit Costs, Reasonably Possible Additional Loss 7  
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning balance 7 8
Provisions/Adjustments 3 1
Cash reductions (1) (2)
Ending balance $ 9 $ 7