v2.4.0.6
Debt (Details Textual) (USD $)
3 Months Ended 12 Months Ended
Jun. 30, 2011
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Mar. 31, 2011
Mar. 31, 2010
Extinguishment of Debt [Line Items]            
Principal amount of debt   $ 7,092,200,000 $ 7,048,400,000      
Derivative [Line Items]            
Notional value of swap agreements 725,000,000 0     725,000,000 500,000,000
Debt (Textual) [Abstract]            
Aggregate amount under Amended and Restated Credit Facility   500,000,000        
Non cash discount premiums and other fair value related adjustments   170,400,000        
Interest Paid   396,200,000 417,800,000 471,600,000    
Reduction in existing credit facility   1,250,000,000        
Balance availability under Letters of Credit Facilities   1,515,400,000 1,637,500,000      
Restricted cash   189,600,000        
Proceeds from the issuance of tax-exempt bonds and other tax-exempt financings   22,500,000        
Capital lease liabilities   88,300,000 91,800,000      
Maximum fixed interest rate related to the interest rate derivative 3.10%       3.10%  
Minimum fixed interest rate related to the interest rate derivative 4.61%       4.61%  
Payment upon termination of Interest rate contract           7,000,000
Interest expense over the life of the issued debt   1,500,000       300,000
Amount of interest rate locks terminated 36,500,000          
Amortization of Interest Cost   0        
Percentage of tax-exempt financings   75.00%        
Interest Rate Swap [Member]
           
Derivative [Line Items]            
Interest at fixed rates   6.75%        
Notional value of swap agreements   210,000,000        
$350.0 million 6.500% senior notes due 2010 [Member]
           
Extinguishment of Debt [Line Items]            
Debt instrument, interest rate, stated percentage   6.50%        
5.700% senior notes due 2041       128,400,000    
$400.0 million 5.750% senior notes due 2011 [Member]
           
Extinguishment of Debt [Line Items]            
Debt instrument, interest rate, stated percentage   5.75%        
5.700% senior notes due 2041       137,100,000    
$275.0 million 6.375% senior notes due 2011 [Member]
           
Extinguishment of Debt [Line Items]            
Debt instrument, interest rate, stated percentage   6.375%        
5.700% senior notes due 2041       58,100,000    
$450.0 million 6.750% senior notes due 2011 [Member]
           
Extinguishment of Debt [Line Items]            
Debt instrument, interest rate, stated percentage   6.75%        
5.700% senior notes due 2041       63,000,000    
$450.0 million 7.875% senior notes due April 2013 [Member]
           
Extinguishment of Debt [Line Items]            
5.700% senior notes due 2041       450,000,000    
$400.0 million of 7.375% senior notes due 2014 [Member]
           
Extinguishment of Debt [Line Items]            
Debt instrument, interest rate, stated percentage   5.75%   7.375%    
5.700% senior notes due 2041       400,000,000    
$230.0 million of 4.250% senior convertible note due 2034 [Member]
           
Extinguishment of Debt [Line Items]            
5.700% senior notes due 2041       230,000,000    
Repurchase of $5,000,000 of 6.375% Senior Notes due 2011 (Aug) [Member]
           
Extinguishment of Debt [Line Items]            
Debt instrument, interest rate, stated percentage   6.375%        
$425.0 million 6.125% senior notes due February 2014 [Member]
           
Extinguishment of Debt [Line Items]            
5.700% senior notes due 2041     $ 425,000,000      
Repurchase of $62,028,000 of 6.750% Senior Notes due 2011 [Member]
           
Extinguishment of Debt [Line Items]            
Debt instrument, interest rate, stated percentage   6.75%