v2.4.0.6
Commitments And Contingencies (Narrative) (Details) (USD $)
 3 Months Ended
Mar. 31, 2013
Dec. 31, 2012
Dec. 31, 2009
Valuation and Qualifying Accounts [Abstract]      
Loss exposure in excess of accrual, high estimate $ 84,000,000    
Probable insurance recoveries 781,000,000 [1],[2] 781,000,000 [1],[2]  
Reserves for legal matters 834,000,000 [3],[4] 846,000,000 [3],[4]  
Minimum [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Estimated cost of complying with recently issued and proposed EPA regulations 5,000,000,000    
Maximum [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Estimated cost of complying with recently issued and proposed EPA regulations 6,000,000,000    
Alaskan Global Warming Lawsuit [Member] | Minimum [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Amount of claim(s) 95,000,000    
Alaskan Global Warming Lawsuit [Member] | Maximum [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Amount of claim(s) 400,000,000    
Brazil Expansion Lawsuit [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Obligation to expand installed generation capacity, percent 15.00%    
Crescent Litigation [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Amount of claim(s) 1,200,000,000    
Duke Energy Carolinas [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Loss exposure in excess of accrual, high estimate 29,000,000    
New Source Review maximum civil penalties per day for each violation 37,500    
Probable insurance recoveries 781,000,000 [1],[2] 781,000,000 [1],[2]  
Reserves for legal matters 743,000,000 [3],[4] 751,000,000 [3],[4]  
Duke Energy Carolinas [Member] | Asbestos Issue [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Number of nonmalignant asbestos related claims 99    
Cumulative relief sought for nonmalignant asbestos related claims 18,000,000    
Number of malignant asbestos related claims 46    
Cumulative relief sought for malignant asbestos related claims 15,000,000    
Asbestos-related injuries and damages reserves 743,000,000 751,000,000  
Asbestos related injuries and damages self insured retention 476,000,000    
Policy limit for potential future insurance recoveries for indemnification and medical cost claim payments in excess of self insured limit 935,000,000    
Progress Energy [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Loss exposure in excess of accrual, high estimate 7,000,000    
Reserves for legal matters 75,000,000 [3] 79,000,000 [3]  
Progress Energy [Member] | Spent Nuclear Fuels [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Gain contingency asserted damage 113,000,000    
Progress Energy [Member] | Synthetic Fuels [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Judgment payment     154,000,000
Damages awarded to plaintiff 90,000,000    
Gain recognized in period   63,000,000  
Duke Energy Progress [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Loss exposure in excess of accrual, high estimate 3,000,000    
Reserves for legal matters 11,000,000 [3] 12,000,000 [3]  
Duke Energy Progress [Member] | Spent Nuclear Fuels [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Gain contingency asserted damage 90,000,000    
Duke Energy Florida [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Loss exposure in excess of accrual, high estimate 4,000,000    
Reserves for legal matters 44,000,000 [3],[5] 47,000,000 [3],[5]  
Duke Energy Florida [Member] | Spent Nuclear Fuels [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Gain contingency asserted damage 23,000,000    
Duke Energy Ohio [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Loss exposure in excess of accrual, high estimate 43,000,000    
Duke Energy Indiana [Member]
      
Valuation and Qualifying Accounts [Abstract]      
Loss exposure in excess of accrual, high estimate 5,000,000    
Reserves for legal matters $ 7,000,000 [3] $ 8,000,000 [3]  
[1] Insurance recoveries are classified in the respective Condensed Consolidated Balance Sheets in Other within Investments and Other Assets and Receivables.
[2] Relates to recoveries associated with aforementioned asbestos-related injuries and damages claims.
[3] Reserves are classified in the respective Condensed Consolidated Balance Sheets in Other within Deferred Credits and Other Liabilities and Other within Current Liabilities.
[4] Includes reserves for aforementioned asbestos-related injuries and damages claims.
[5] Includes workers' compensation claims.