v2.4.0.6
Debt (Textuals 1) (Details) (USD $)
 6 Months Ended 12 Months Ended
Jun. 30, 2011
Dec. 31, 2011
Dec. 31, 2010
Sep. 01, 2011
Dec. 31, 2009
Debt Instrument [Line Items]          
Number of power plants         6
Power generation capacity   11,391 13,656    
Payments of Debt Issuance Costs   $ 22,000,000      
Write off of Deferred Debt Issuance Cost     19,000,000    
Debt Disclosure [Abstract]          
Early Repayment of Senior Debt   1,200,000,000 3,500,000,000    
Repayment of Project Debt       340,000,000  
Term loan interest rate spread option Federal Funds effective rate   0.50%      
Term loan interest rate spread option Prime Rate   2.25%      
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum   3.25%      
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum   1.25%      
Percentage of principal amount of Term Loan to be paid quarterly   0.25%      
Repricing transaction premium percentage   1.00%      
Days allowed to make offer to prepay   30      
Percentage of Term Loan amounts held by lenders   50.00%      
Deferred Finance Costs, Gross   14,000,000      
Term Loan debt extinguishment costs 74,000,000 5,000,000      
Write-off amount of unamortized deferred financing costs 36,000,000        
Write-off amount of debt discount 25,000,000        
Subsidiary Project Debt prepayment premiums 13,000,000        
Back-Stopped Letters of Credit   83,000,000      
Percentage added to Federal Funds Effective Rate to arrive at base rate   0.50%      
Repayment time for drawings under letters of credit   2      
Line of Credit Facility, Maximum Borrowing Capacity   1,000,000,000      
Equity Method Investment, Ownership Percentage   50.00%      
Excess amount of asset sales requiring mandatory prepayments   3,000,000,000      
CDHI Letter of Credit Facility Total   200,000,000      
CDHI Upsize Facility Total   $ 300,000,000      
Debt, Weighted Average Interest Rate   8.90% 8.90%    
Minimum [Member]
          
Debt Disclosure [Abstract]          
Applicable margin range percentage above base rate   2.00%      
Applicable Margin Range Percentage Above British Bankers' Association Interest Settlement Rates   3.00%      
Unused commitment fee range percentage   0.50%      
Maximum [Member]
          
Debt Disclosure [Abstract]          
Applicable margin range percentage above base rate   2.25%      
Applicable Margin Range Percentage Above British Bankers' Association Interest Settlement Rates   3.25%      
Unused commitment fee range percentage   0.75%      
One Month [Member]
          
Debt Disclosure [Abstract]          
Interest periods for LIBOR rate borrowings   1      
Two Months [Member]
          
Debt Disclosure [Abstract]          
Interest periods for LIBOR rate borrowings   2      
Three Months [Member]
          
Debt Disclosure [Abstract]          
Interest periods for LIBOR rate borrowings   3      
Six Months [Member]
          
Debt Disclosure [Abstract]          
Interest periods for LIBOR rate borrowings   6      
Nine Months [Member]
          
Debt Disclosure [Abstract]          
Interest periods for LIBOR rate borrowings   9      
Twelve Months [Member]
          
Debt Disclosure [Abstract]          
Interest periods for LIBOR rate borrowings   12