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Fair Value of Financial Assets and Liabilities (Tables)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Dec. 31, 2012
Fair Value Disclosures [Line Items]          
Fair Value Measurement Amounts For Assets And Liabilities    
              
   June 30, 2013
(in millions) Total Fair Value Level 1   Level 2   Level 3
Investments in available-for-sale auction rate securities(a) $ 26 $ ― $ ― $ 26
Nuclear decommissioning trust fund equity securities   3,170   3,086   63   21
Nuclear decommissioning trust fund debt securities   1,397   332   1,015   50
Other trading and available-for-sale equity securities(b)   88   78   10   ―
Other trading and available-for-sale debt securities(c)   580   64   516   ―
Derivative assets(b)   102   22   10   70
 Total assets   5,363   3,582   1,614   167
Derivative liabilities(d)   (549)   (8)   (384)   (157)
 Net assets $ 4,814 $ 3,574 $ 1,230 $ 10
  
              
   December 31, 2012
(in millions) Total Fair Value Level 1  Level 2  Level 3
Investments in available-for-sale auction rate securities(a) $ 29 $ ― $ ― $ 29
Nuclear decommissioning trust fund equity securities   2,837   2,762   54   21
Nuclear decommissioning trust fund debt securities   1,405   317   1,040   48
Other trading and available-for-sale equity securities(b)   72   63   9   ―
Other trading and available-for-sale debt securities(c)   602   40   562   ―
Derivative assets(b)   103   18   22   63
 Total assets   5,048   3,200   1,687   161
Derivative liabilities(d)   (756)   (17)   (591)   (148)
 Net assets $ 4,292 $ 3,183 $ 1,096 $ 13
              
(a) Included in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.
(b)Included in Other within Current Assets and Other within Investments and Other Assets on the Condensed Consolidated Balance Sheet.
(c) Included in Other within Investments and Other Assets and Short-term Investments on the Condensed Consolidated Balance Sheets.
(d) Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets.
              
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs
   Three Months Ended June 30, 2013
(in millions)Available-for-Sale Auction Rate Securities  Available-for-Sale NDTF Investments Derivatives (net)  Total
Balance at March 31, 2013$ 28 $ 70 $ (82) $ 16
Total pretax realized or unrealized gains (losses) included in earnings:           
 Regulated electric  ―   ―   8   8
 Revenue, nonregulated electric, natural gas, and other  ―   ―   (19)   (19)
Total pretax gains included in other comprehensive income:           
 Losses on available for sale securities and other  (1)   ―   ―   (1)
Purchases, sales, issuances and settlements:           
 Purchases  ―   3   21   24
 Sales  ―   (3)   ―   (3)
 Settlements  (1)   ―   (9)   (10)
Total gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability  ―   1   (6)   (5)
Balance at June 30, 2013$ 26 $ 71 $ (87) $ 10
Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013           
 Regulated electric$ ― $ ― $ 1 $ 1
 Revenue, nonregulated electric, natural gas, and other  ―   ―   (14)   (14)
Total$ ― $ ― $ (13) $ (13)
              
              
   Three Months Ended June 30, 2012
(in millions)Available-for-Sale Auction Rate Securities  Available-for-Sale NDTF Investments Derivatives (net)  Total
Balance at March 31, 2012$ 72 $ 56 $ (42) $ 86
Total pretax realized or unrealized gains (losses) included in earnings:           
 Regulated electric  ―   ―   17   17
 Revenue, nonregulated electric, natural gas, and other  ―   ―   (1)   (1)
Total pretax gains included in other comprehensive income:           
 Gains on available for sale securities and other  8   ―   ―   8
Purchases, sales, issuances and settlements:           
 Purchases  ―   7   22   29
 Settlements  (39)   ―   (15)   (54)
Total gains included on the Condensed Consolidated Balance Sheet as regulatory asset or liability  ―   1   ―   1
Balance at June 30, 2012$ 41 $ 64 $ (19) $ 86
   Six Months Ended June 30, 2013
(in millions)Available-for-Sale Auction Rate Securities Available-for-Sale NDTF Investments Derivatives (net)  Total
Balance at December 31, 2012$ 29 $ 69 $ (85) $ 13
Total pretax realized or unrealized losses included in earnings:           
 Regulated electric  ―   ―   2   2
 Revenue, nonregulated electric, natural gas, and other  ―   ―   (23)   (23)
Total pretax gains included in other comprehensive income:           
 Losses on available for sale securities and other  (2)   ―   ―   (2)
Purchases, sales, issuances and settlements:           
 Purchases  ―   3   21   24
 Sales  ―   (3)   ―   (3)
 Issuances  ―   ―   6   6
 Settlements  (1)   ―   (2)   (3)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability  ―   2   (6)   (4)
Balance at June 30, 2013$ 26 $ 71 $ (87) $ 10
Pretax amounts included in the Condensed Consolidated Statement of Operations related to Level 3 measurements outstanding at June 30, 2013           
 Regulated electric$ ― $ ― $ 2 $ 2
 Revenue, nonregulated electric, natural gas, and other  ―   ―   (24)   (24)
Total$ ― $ ― $ (22) $ (22)
              
   Six Months Ended June 30, 2012
(in millions)Available-for-Sale Auction Rate Securities Available-for-Sale NDTF Investments Derivatives (net)  Total
Balance at December 31, 2011$ 71 $ 53 $ (39) $ 85
Total pretax realized or unrealized losses included in earnings:           
 Regulated electric  ―   ―   25   25
 Revenue, nonregulated electric, natural gas, and other  ―   ―   (3)   (3)
Total pretax gains included in other comprehensive income:           
 Gains on available for sale securities and other  9   ―   ―   9
Purchases, sales, issuances and settlements:           
 Purchases  ―   9   22   31
 Settlements  (39)   ―   (24)   (63)
Total gains included on the Condensed Consolidated Balance Sheet as regulatory asset or liability  ―   2   ―   2
Balance at June 30, 2012$ 41 $ 64 $ (19) $ 86
Pretax amounts included in the Condensed Consolidated Statement of Operations related to Level 3 measurements outstanding at June 30, 2012.           
 Revenue, nonregulated electric, natural gas, and other$ ― $ ― $ 3 $ 3
Total$ ― $ ― $ 3 $ 3
              
  
Schedule of Long-term debt, including current    
  June 30, 2013 December 31, 2012
(in millions)Book Value Fair Value Book Value Fair Value
Duke Energy (a)$ 39,582 $ 42,099 $ 39,461 $ 44,001
Duke Energy Carolinas(b)  8,740   9,461   8,741   10,096
Progress Energy  14,220   15,462   14,428   16,563
Duke Energy Progress  5,336   5,488   4,840   5,277
Duke Energy Florida  4,892   5,433   5,320   6,222
Duke Energy Ohio  1,742   1,809   1,997   2,117
Duke Energy Indiana  3,701   4,049   3,702   4,268
             
(a)Includes book value of Non-recourse long-term debt of variable interest entities of $1,259 million and $852 million June 30, 2013 and December 31, 2012, respectively.
(b)Includes book value of Non-recourse long-term debt of variable interest entities of $300 million at both June 30, 2013 and December 31, 2012, respectively.
             
    
Quantitative Information Table - Level 3    
  June 30, 2013
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (82) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.91- 10.36
FERC mitigation power sale agreements (8) Discounted cash flow Forward electricity curves - price per MWh  23.15- 49.29
Financial transmission rights (FTRs) 19 RTO market pricing FTR price  (3.25)- 10.83
Commodity power contracts 3 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  2.91- 4.88
Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves - price per MW day  29.80- 85.70
Reserves (18)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(87)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(4) Discounted cash flow Forward electricity curves - price per MWh$ 25.92- 49.29
Progress Energy          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Progress          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ (0.20)- 0.94
Commodity power contracts  11 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity natural gas contracts  (14) Discounted cash flow Forward natural gas curves - price per MMBtu  2.91- 4.88
Reserves  (17)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(19)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 18 RTO market pricing FTR price$ (3.25)- 10.83
            
  
            
  December 31, 2012
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (53) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.33- 9.99
FERC mitigation power sale agreements (23) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Financial transmission rights (FTRs) 11 RTO market pricing FTR price  23.63- 39.22
Commodity power contracts (8) Discounted cash flow Forward electricity curves - price per MWh  24.82- 77.96
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  95.16- 105.36
Commodity capacity option contracts 3 Discounted cash flow Forward capacity option curves - price per MW day  4.68- 77.96
Reserves (12)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(85)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(12) Discounted cash flow Forward electricity curves - price per MWh$ 25.83- 48.69
Progress Energy          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Progress          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ 27.17- 39.22
Commodity power contracts  (1) Discounted cash flow Forward electricity curves - price per MWh  25.90- 57.50
Commodity natural gas contracts  5 Discounted cash flow Forward natural gas curves - price per MMBtu  3.30- 4.51
Reserves  (11)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(6)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 10 RTO market pricing FTR price$ 23.63- 35.43
            
Duke Energy Carolinas [Member]
          
Fair Value Disclosures [Line Items]          
Fair Value Measurement Amounts For Assets And Liabilities    
              
    June 30, 2013
(in millions) Total Fair Value Level 1  Level 2  Level 3
Investments in available-for-sale auction rate securities(a) $ 3 $ ― $ ― $ 3
Nuclear decommissioning trust fund equity securities   1,763   1,689   53   21
Nuclear decommissioning trust fund debt securities   770   172   548   50
 Total assets   2,536   1,861   601   74
Derivative liabilities(b)   (4)   ―   ―   (4)
 Net assets $ 2,532 $ 1,861 $ 601 $ 70
  
              
   December 31, 2012
(in millions) Total Fair Value Level 1  Level 2  Level 3
Investments in available-for-sale auction rate securities(a) $ 3 $ ― $ ― $ 3
Nuclear decommissioning trust fund equity securities   1,592   1,523   48   21
Nuclear decommissioning trust fund debt securities   762   155   559   48
 Total assets   2,357   1,678   607   72
Derivative liabilities(b)   (12)   ―   ―   (12)
 Net Assets $ 2,345 $ 1,678 $ 607 $ 60
              
(a)Included in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.
(b)Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheet.
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs
   Three Months Ended June 30, 2013
(in millions)Available-for-Sale Auction Rate Securities  Available-for-Sale NDTF Investments Derivatives (net) Total
Balance at March 31, 2013$ 3 $ 70 $ (5) $ 68
Purchases, sales, issuances and settlements:           
 Purchases  ―   3   ―   3
 Sales  ―   (3)   ―   (3)
 Settlements  ―   ―   1   1
Total gains included on the Condensed Consolidated Balance Sheet as regulatory asset or liability  ―   1   ―   1
Balance at June 30, 2013$ 3 $ 71 $ (4) $ 70
Pretax amounts included in the Condensed Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013           
 Regulated electric$ ― $ ― $ 1 $ 1
Total$ ― $ ― $ 1 $ 1
              
              
   Three Months Ended June 30, 2012
(in millions)Available-for-Sale Auction Rate Securities  Available-for-Sale NDTF Investments Derivatives (net) Total
Balance at March 31, 2012$ 12 $ 56 $ ― $ 68
Total pretax gains included in other comprehensive income:           
 Gains on available for sale securities and other  2   ―   ―   2
Purchases, sales, issuances and settlements:           
 Purchases  ―   7   ―   7
 Settlements  (8)   ―   ―   (8)
Total gains included on the Condensed Consolidated Balance Sheet as regulatory asset or liability  ―   1   ―   1
Balance at June 30, 2012$ 6 $ 64 $ ― $ 70
              
   Six Months Ended June 30, 2013
(in millions)Available-for-Sale Auction Rate Securities  Available-for-Sale NDTF Investments Derivatives (net) Total
Balance at December 31, 2012$ 3 $ 69 $ (12) $ 60
Purchases, sales, issuances and settlements:           
 Purchases  ―   3   ―   3
 Sales  ―   (3)   ―   (3)
 Settlements  ―   ―   8   8
Total gains included on the Consolidated Balance Sheet as regulatory asset or liability  ―   2   ―   2
Balance at June 30, 2013$ 3 $ 71 $ (4) $ 70
Pretax amounts included in the Condensed Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013           
 Regulated electric$ ― $ ― $ (4) $ (4)
Total$ ― $ ― $ (4) $ (4)
              
   Six Months Ended June 30, 2012
(in millions)Available-for-Sale Auction Rate Securities  Available-for-Sale NDTF Investments Derivatives (net) Total
Balance at December 31, 2011$ 12 $ 53 $ ― $ 65
Total pretax gains included in other comprehensive income:           
 Gains on available for sale securities and other  2   ―   ―   2
Purchases, sales, issuances and settlements:           
 Purchases  ―   9   ―   9
 Settlements  (8)   ―   ―   (8)
Total gains included on the Condensed Consolidated Balance Sheet as regulatory asset or liability  ―   2   ―   2
Balance at June 30, 2012$ 6 $ 64 $ ― $ 70
              
  
Quantitative Information Table - Level 3    
  June 30, 2013
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (82) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.91- 10.36
FERC mitigation power sale agreements (8) Discounted cash flow Forward electricity curves - price per MWh  23.15- 49.29
Financial transmission rights (FTRs) 19 RTO market pricing FTR price  (3.25)- 10.83
Commodity power contracts 3 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  2.91- 4.88
Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves - price per MW day  29.80- 85.70
Reserves (18)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(87)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(4) Discounted cash flow Forward electricity curves - price per MWh$ 25.92- 49.29
Progress Energy          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Progress          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ (0.20)- 0.94
Commodity power contracts  11 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity natural gas contracts  (14) Discounted cash flow Forward natural gas curves - price per MMBtu  2.91- 4.88
Reserves  (17)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(19)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 18 RTO market pricing FTR price$ (3.25)- 10.83
            
  
            
  December 31, 2012
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (53) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.33- 9.99
FERC mitigation power sale agreements (23) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Financial transmission rights (FTRs) 11 RTO market pricing FTR price  23.63- 39.22
Commodity power contracts (8) Discounted cash flow Forward electricity curves - price per MWh  24.82- 77.96
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  95.16- 105.36
Commodity capacity option contracts 3 Discounted cash flow Forward capacity option curves - price per MW day  4.68- 77.96
Reserves (12)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(85)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(12) Discounted cash flow Forward electricity curves - price per MWh$ 25.83- 48.69
Progress Energy          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Progress          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ 27.17- 39.22
Commodity power contracts  (1) Discounted cash flow Forward electricity curves - price per MWh  25.90- 57.50
Commodity natural gas contracts  5 Discounted cash flow Forward natural gas curves - price per MMBtu  3.30- 4.51
Reserves  (11)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(6)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 10 RTO market pricing FTR price$ 23.63- 35.43
            
Progress Energy [Member]
          
Fair Value Disclosures [Line Items]          
Fair Value Measurement Amounts For Assets And Liabilities    
              
   June 30, 2013
(in millions) Total Fair Value Level 1   Level 2   Level 3
Nuclear decommissioning trust fund equity securities $ 1,407 $ 1,397 $ 10 $ ―
Nuclear decommissioning trust fund debt securities and other   627   160   467   ―
Other trading and available-for-sale debt securities and other(a)   59   19   40   ―
Derivative assets(b)   ―   ―   ―   ―
 Total assets   2,093   1,576   517   ―
Derivative liabilities(c)   (325)   ―   (290)   (35)
 Net assets $ 1,768 $ 1,576 $ 227 $ (35)
  
              
   December 31, 2012
(in millions) Total Fair Value Level 1   Level 2   Level 3
Nuclear decommissioning trust fund equity securities $ 1,245 $ 1,239 $ 6 $ ―
Nuclear decommissioning trust fund debt securities and other   643   162   481   ―
Other trading and available-for-sale debt securities and other(a)   57   17   40   ―
Derivative assets(b)   11   ―   11   ―
 Total assets   1,956   1,418   538   ―
Derivative liabilities(c)   (440)   ―   (402)   (38)
 Net assets $ 1,516 $ 1,418 $ 136 $ (38)
              
(a)Included in Other within Investments and Other Assets in the Condensed Consolidated Balance Sheets.
(b)Included in Other Current Assets within Current Assets and Other within Investments and Other Assets in the Condensed Consolidated Balance Sheets.
(c)Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities in the Condensed Consolidated Balance Sheets.
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs
   Derivatives (net)
   Three Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ (31) $ (27)
Purchases, sales, issuances and settlements:      
 Issuances   1   ―
Total losses included on the Condensed Consolidated Balance Sheet as regulatory asset or liability   (5)   (3)
Balance at end of period $ (35) $ (30)
         
  
         
   Derivatives (net)
   Six Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ (38) $ (24)
Purchases, sales, issuances and settlements:      
 Issuances   7   ―
Total losses included on the Condensed Consolidated Balance Sheet as regulatory asset or liability   (4)   (6)
Balance at end of period $ (35) $ (30)
Pretax amounts included in the Condensed Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013      
 Regulated electric $ 6 $ ―
Total $ 6 $ ―
         
    
Quantitative Information Table - Level 3    
  June 30, 2013
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (82) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.91- 10.36
FERC mitigation power sale agreements (8) Discounted cash flow Forward electricity curves - price per MWh  23.15- 49.29
Financial transmission rights (FTRs) 19 RTO market pricing FTR price  (3.25)- 10.83
Commodity power contracts 3 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  2.91- 4.88
Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves - price per MW day  29.80- 85.70
Reserves (18)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(87)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(4) Discounted cash flow Forward electricity curves - price per MWh$ 25.92- 49.29
Progress Energy          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Progress          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ (0.20)- 0.94
Commodity power contracts  11 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity natural gas contracts  (14) Discounted cash flow Forward natural gas curves - price per MMBtu  2.91- 4.88
Reserves  (17)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(19)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 18 RTO market pricing FTR price$ (3.25)- 10.83
            
  
            
  December 31, 2012
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (53) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.33- 9.99
FERC mitigation power sale agreements (23) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Financial transmission rights (FTRs) 11 RTO market pricing FTR price  23.63- 39.22
Commodity power contracts (8) Discounted cash flow Forward electricity curves - price per MWh  24.82- 77.96
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  95.16- 105.36
Commodity capacity option contracts 3 Discounted cash flow Forward capacity option curves - price per MW day  4.68- 77.96
Reserves (12)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(85)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(12) Discounted cash flow Forward electricity curves - price per MWh$ 25.83- 48.69
Progress Energy          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Progress          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ 27.17- 39.22
Commodity power contracts  (1) Discounted cash flow Forward electricity curves - price per MWh  25.90- 57.50
Commodity natural gas contracts  5 Discounted cash flow Forward natural gas curves - price per MMBtu  3.30- 4.51
Reserves  (11)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(6)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 10 RTO market pricing FTR price$ 23.63- 35.43
            
Duke Energy Progress [Member]
          
Fair Value Disclosures [Line Items]          
Fair Value Measurement Amounts For Assets And Liabilities    
              
   June 30, 2013
(in millions) Total Fair Value  Level 1   Level 2   Level 3
Nuclear decommissioning trust fund equity securities $ 918 $ 918 $ ― $ ―
Nuclear decommissioning trust fund debt securities and other   442   124   318   ―
Other trading and available-for-sale debt securities and other(a)   2   2   ―   ―
Derivative assets(b)   ―   ―   ―   ―
 Total assets   1,362   1,044   318   ―
Derivative liabilities(c)   (124)   ―   (89)   (35)
 Net assets $ 1,238 $ 1,044 $ 229 $ (35)
              
  
              
   December 31, 2012
(in millions) Total Fair Value Level 1   Level 2   Level 3
Nuclear decommissioning trust fund equity securities $ 811 $ 811 $ ― $ ―
Nuclear decommissioning trust fund debt securities and other   448   119   329   ―
Other trading and available-for-sale debt securities and other(a)   3   3   ―   ―
Derivative assets(b)   2   ―   2   ―
 Total assets   1,264   933   331   ―
Derivative liabilities(c)   (166)   ―   (128)   (38)
 Net assets $ 1,098 $ 933 $ 203 $ (38)
              
(a)Included in Other within Investments and Other Assets in the Condensed Consolidated Balance Sheets.
(b)Included in Other Current Assets within Current Assets and Other within Investments and Other Assets in the Condensed Consolidated Balance Sheets.
(c) Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities in the Condensed Consolidated Balance Sheets.
              
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs
   Derivatives (net)
   Three Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ (31) $ (27)
Purchases, sales, issuances and settlements:      
 Issuances   1   ―
Total losses included on the Condensed Consolidated Balance Sheet as regulatory asset or liability   (5)   (1)
Balance at end of period $ (35) $ (28)
Pretax amounts included in the Condensed Consolidated Statements of Operations and Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013      
 Regulated electric $ 1 $ ―
Total $ 1 $ ―
         
  
    
   Derivatives (net)
   Six Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ (38) $ (24)
Purchases, sales, issuances and settlements:      
 Issuances   7   ―
 Settlements   ―   ―
Total losses included on the Condensed Consolidated Balance Sheet as regulatory asset or liability   (4)   (4)
Balance at end of period $ (35) $ (28)
Pretax amounts included in the Condensed Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013      
 Regulated electric $ 7 $ ―
Total $ 7 $ ―
         
    
Quantitative Information Table - Level 3    
  June 30, 2013
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (82) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.91- 10.36
FERC mitigation power sale agreements (8) Discounted cash flow Forward electricity curves - price per MWh  23.15- 49.29
Financial transmission rights (FTRs) 19 RTO market pricing FTR price  (3.25)- 10.83
Commodity power contracts 3 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  2.91- 4.88
Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves - price per MW day  29.80- 85.70
Reserves (18)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(87)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(4) Discounted cash flow Forward electricity curves - price per MWh$ 25.92- 49.29
Progress Energy          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Progress          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ (0.20)- 0.94
Commodity power contracts  11 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity natural gas contracts  (14) Discounted cash flow Forward natural gas curves - price per MMBtu  2.91- 4.88
Reserves  (17)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(19)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 18 RTO market pricing FTR price$ (3.25)- 10.83
            
  
            
  December 31, 2012
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (53) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.33- 9.99
FERC mitigation power sale agreements (23) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Financial transmission rights (FTRs) 11 RTO market pricing FTR price  23.63- 39.22
Commodity power contracts (8) Discounted cash flow Forward electricity curves - price per MWh  24.82- 77.96
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  95.16- 105.36
Commodity capacity option contracts 3 Discounted cash flow Forward capacity option curves - price per MW day  4.68- 77.96
Reserves (12)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(85)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(12) Discounted cash flow Forward electricity curves - price per MWh$ 25.83- 48.69
Progress Energy          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Progress          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ 27.17- 39.22
Commodity power contracts  (1) Discounted cash flow Forward electricity curves - price per MWh  25.90- 57.50
Commodity natural gas contracts  5 Discounted cash flow Forward natural gas curves - price per MMBtu  3.30- 4.51
Reserves  (11)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(6)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 10 RTO market pricing FTR price$ 23.63- 35.43
            
Duke Energy Florida [Member]
          
Fair Value Disclosures [Line Items]          
Fair Value Measurement Amounts For Assets And Liabilities    
              
   June 30, 2013
(in millions) Total Fair Value Level 1   Level 2   Level 3
Nuclear decommissioning trust fund equity securities $ 489 $ 479 $ 10 $ ―
Nuclear decommissioning trust fund debt securities and other   185   36   149   ―
Other trading and available-for-sale debt securities and other(a)   43   3   40   ―
Derivative assets(b)   ―   ―   ―   ―
 Total assets   717   518   199   ―
Derivative liabilities(c)   (197)   ―   (197)   ―
 Net assets $ 520 $ 518 $ 2 $ ―
              
  
              
   December 31, 2012
(in millions) Total Fair Value Level 1   Level 2   Level 3
Nuclear decommissioning trust fund equity securities $ 435 $ 429 $ 6 $ ―
Nuclear decommissioning trust fund debt securities and other   194   43   151   ―
Other trading and available-for-sale debt securities and other(a)   43   3   40   ―
Derivative assets(b)   9   ―   9   ―
 Total assets   681   475   206   ―
Derivative liabilities(c)   (270)   ―   (270)   ―
 Net assets (liabilities) $ 411 $ 475 $ (64) $ ―
              
(a)Included in Other within Investments and Other Assets in the Condensed Balance Sheets.
(b)Included in Other Current Assets within Current Assets and Other within Investments and Other Assets in the Condensed Balance Sheets.
(c)Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities in the Condensed Balance Sheets
              
Duke Energy Ohio [Member]
          
Fair Value Disclosures [Line Items]          
Fair Value Measurement Amounts For Assets And Liabilities    
              
   June 30, 2013
(in millions) Total Fair Value Level 1   Level 2   Level 3
Derivative assets(a) $ 55 $ 39 $ ― $ 16
Derivative liabilities(b)   (46)   (5)   (6)   (35)
 Net liabilities $ 9 $ 34 $ (6) $ (19)
              
  
              
   December 31, 2012
(in millions) Total Fair Value Level 1   Level 2   Level 3
Derivative assets(a) $ 59 $ 48 $ 2 $ 9
Derivative liabilities(b)   (38)   (15)   (8)   (15)
 Net assets (liabilities) $ 21 $ 33 $ (6) $ (6)
              
(a)Included in Other within Current Assets and Other within Investments and Other Assets in the Condensed Consolidated Balance Sheets.
(b)Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities in the Condensed Consolidated Balance Sheets.
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs
   Derivatives (net)
   Three Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ (5) $ (4)
Total pretax realized or unrealized gains (losses) included in earnings:      
 Revenue, nonregulated electric, natural gas, and other   (14)   1
Purchases, sales, issuances and settlements:      
 Purchases   1   ―
 Settlements   ―   2
Total losses included on the Condensed Consolidated Balance Sheet as regulatory asset or liability   (1)   (1)
Balance at end of period $ (19) $ (2)
Pretax amounts included in the Condensed Consolidated Statements of Operations and Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013:      
 Revenue, non-regulated electric and other $ (11) $ ―
Total $ (11) $ ―
         
  
         
   Derivatives (net)
   Six Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ (6) $ (3)
Total pretax realized or unrealized gains (losses) included in earnings:      
 Revenue, nonregulated electric, natural gas, and other   (10)   1
Purchases, sales, issuances and settlements:      
 Purchases   1   ―
 Settlements   (3)   2
Total losses included on the Condensed Consolidated Balance Sheet as regulatory asset or liability   (1)   (2)
Balance at end of period $ (19) $ (2)
Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at June 30, 2013:      
 Revenue, non-regulated electric and other $ (13) $ 1
Total $ (13) $ 1
         
    
Quantitative Information Table - Level 3    
  June 30, 2013
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (82) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.91- 10.36
FERC mitigation power sale agreements (8) Discounted cash flow Forward electricity curves - price per MWh  23.15- 49.29
Financial transmission rights (FTRs) 19 RTO market pricing FTR price  (3.25)- 10.83
Commodity power contracts 3 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  2.91- 4.88
Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves - price per MW day  29.80- 85.70
Reserves (18)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(87)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(4) Discounted cash flow Forward electricity curves - price per MWh$ 25.92- 49.29
Progress Energy          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Progress          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ (0.20)- 0.94
Commodity power contracts  11 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity natural gas contracts  (14) Discounted cash flow Forward natural gas curves - price per MMBtu  2.91- 4.88
Reserves  (17)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(19)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 18 RTO market pricing FTR price$ (3.25)- 10.83
            
  
            
  December 31, 2012
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (53) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.33- 9.99
FERC mitigation power sale agreements (23) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Financial transmission rights (FTRs) 11 RTO market pricing FTR price  23.63- 39.22
Commodity power contracts (8) Discounted cash flow Forward electricity curves - price per MWh  24.82- 77.96
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  95.16- 105.36
Commodity capacity option contracts 3 Discounted cash flow Forward capacity option curves - price per MW day  4.68- 77.96
Reserves (12)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(85)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(12) Discounted cash flow Forward electricity curves - price per MWh$ 25.83- 48.69
Progress Energy          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Progress          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ 27.17- 39.22
Commodity power contracts  (1) Discounted cash flow Forward electricity curves - price per MWh  25.90- 57.50
Commodity natural gas contracts  5 Discounted cash flow Forward natural gas curves - price per MMBtu  3.30- 4.51
Reserves  (11)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(6)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 10 RTO market pricing FTR price$ 23.63- 35.43
            
Duke Energy Indiana [Member]
          
Fair Value Disclosures [Line Items]          
Fair Value Measurement Amounts For Assets And Liabilities    
              
   June 30, 2013
(in millions) Total Fair Value Level 1   Level 2   Level 3
Available-for-sale equity securities(a) $ 56 $ 56 $ ― $ ―
Available-for-sale debt securities(a)   28   ―   28   ―
Derivative assets(b)   18   ―   ―   18
 Total assets   102   56   28 $ 18
Derivative liabilities(c)   (37)   (1)   (36)   ―
 Net assets (liabilities) $ 65 $ 55 $ (8) $ 18
  
              
   December 31, 2012
(in millions) Total Fair Value Level 1   Level 2   Level 3
Available-for-sale equity securities(a) $ 49 $ 49 $ ― $ ―
Available-for-sale debt securities(a)   29   ―   29   ―
Derivative assets(b)   10   ―   ―   10
 Total assets   88   49   29 $ 10
Derivative liabilities(c)   (63)   ―   (63)   ―
 Net assets (liabilities) $ 25 $ 49 $ (34) $ 10
              
(a)Included in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.
(b)Included in Other within Current Assets on the Condensed Consolidated Balance Sheets.
(c)Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets.
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs
   Derivatives (net)
   Three Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ 4 $ 3
Total pretax realized or unrealized gains (losses) included in earnings:      
 Regulated electric   7   16
Purchases, sales, issuances and settlements:      
 Purchases   20   ―
 Sales   ―   22
 Settlements   (13)   (19)
Balance at end of period $ 18 $ 22
         
  
         
   Derivatives (net)
   Six Months Ended June 30,
(in millions)  2013  2012
Balance at beginning of period $ 10 $ 4
Total pretax realized or unrealized gains (losses) included in earnings:      
 Regulated electric   2   24
Purchases, sales, issuances and settlements:      
 Sales   20   22
 Settlements   (13)   (29)
Total (losses) gains included on the Condensed Consolidated Balance Sheet as regulatory asset or liability   (1)   1
Balance at end of period $ 18 $ 22
         
    
Quantitative Information Table - Level 3    
  June 30, 2013
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (82) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.91- 10.36
FERC mitigation power sale agreements (8) Discounted cash flow Forward electricity curves - price per MWh  23.15- 49.29
Financial transmission rights (FTRs) 19 RTO market pricing FTR price  (3.25)- 10.83
Commodity power contracts 3 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  2.91- 4.88
Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves - price per MW day  29.80- 85.70
Reserves (18)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(87)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(4) Discounted cash flow Forward electricity curves - price per MWh$ 25.92- 49.29
Progress Energy          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Progress          
Commodity natural gas contracts$ (31) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.00- 4.39
FERC mitigation power sale agreements (4) Discounted cash flow Forward electricity curves - price per MWh  23.15- 43.56
Total Level 3 derivatives$(35)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ (0.20)- 0.94
Commodity power contracts  11 Discounted cash flow Forward electricity curves - price per MWh  25.30- 55.52
Commodity natural gas contracts  (14) Discounted cash flow Forward natural gas curves - price per MMBtu  2.91- 4.88
Reserves  (17)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(19)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 18 RTO market pricing FTR price$ (3.25)- 10.83
            
  
            
  December 31, 2012
Investment TypeFair Value (in millions) Valuation Technique  Unobservable InputRange
Duke Energy          
Commodity natural gas contracts$ (53) Discounted cash flow Forward natural gas curves - price per MMBtu$ 2.33- 9.99
FERC mitigation power sale agreements (23) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Financial transmission rights (FTRs) 11 RTO market pricing FTR price  23.63- 39.22
Commodity power contracts (8) Discounted cash flow Forward electricity curves - price per MWh  24.82- 77.96
Commodity capacity contracts (3) Discounted cash flow Forward capacity curves - price per MW day  95.16- 105.36
Commodity capacity option contracts 3 Discounted cash flow Forward capacity option curves - price per MW day  4.68- 77.96
Reserves (12)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(85)        
Duke Energy Carolinas          
FERC mitigation power sale agreements$(12) Discounted cash flow Forward electricity curves - price per MWh$ 25.83- 48.69
Progress Energy          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Progress          
Commodity natural gas contracts$ (27) Discounted cash flow Forward natural gas curves - price per MMBtu$ 4.07- 4.45
FERC mitigation power sale agreements (11) Discounted cash flow Forward electricity curves - price per MWh  25.83- 48.69
Total Level 3 derivatives$(38)        
Duke Energy Ohio          
Financial transmission rights (FTRs)$ 1 RTO market pricing FTR price$ 27.17- 39.22
Commodity power contracts  (1) Discounted cash flow Forward electricity curves - price per MWh  25.90- 57.50
Commodity natural gas contracts  5 Discounted cash flow Forward natural gas curves - price per MMBtu  3.30- 4.51
Reserves  (11)   Bid-ask spreads, implied volatility, probability of default    
Total Level 3 derivatives$(6)        
Duke Energy Indiana          
Financial transmission rights (FTRs)$ 10 RTO market pricing FTR price$ 23.63- 35.43