v2.4.0.6
Debt (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Debt    
Principal amount of debt $ 7,092.2 $ 7,048.4
Debt Instrument, Discount (170.4) (304.8)
Debt 6,921.8 6,743.6
Less: Current portion (34.8) (878.5)
Long-term portion 6,887.0 5,865.1
Long term debt, credit facility matured on April 2012 [Member]
   
Debt    
Line of Credit Facility, Interest Rate Variable Variable  
Principal amount of debt 0 25.0
Debt Instrument, Discount 0 0
Debt 0 25.0
Long term debt, credit facility matured on September 2013 [Member]
   
Debt    
Line of Credit Facility, Interest Rate Variable Variable%  
Principal amount of debt 17.2 50.0
Debt Instrument, Discount 0 0
Debt 17.2 50.0
$1.0 billion Revolver due 2012 [Member]
   
Debt    
Line of Credit Facility, Interest Rate Variable Variable  
Principal amount of debt 17.2 0
Debt Instrument, Discount 0 0
Debt 17.2 0
Long term debt, senior note matured on February 2011 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 5.75%  
Principal amount of debt 0 262.9
Debt Instrument, Discount 0 (1.2)
Debt 0 261.7
Long term debt, senior note matured on April 2011 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 6.375%  
Principal amount of debt 0 216.9
Debt Instrument, Discount 0 (1.8)
Debt 0 215.1
Long term debt, senior note matured on August 2011 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 6.75%  
Principal amount of debt 0 392.2
Debt Instrument, Discount 0 (0.2)
Debt 0 392.0
Long term debt, senior note matured on May 2016 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 7.125%  
Principal amount of debt 0 600.0
Debt Instrument, Discount 0 (64.5)
Debt 0 535.5
Long term debt, senior note matured on June 2017 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 6.875%  
Principal amount of debt 750.0 750.0
Debt Instrument, Discount (75.8) (86.1)
Debt 674.2 663.9
Long term debt, senior note matured on May 2018 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 3.80%  
Principal amount of debt 700.0 0
Debt Instrument, Discount (0.2) 0
Debt 699.8 0
Long term debt, senior note matured on September 2019 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 5.50%  
Principal amount of debt 650.0 650.0
Debt Instrument, Discount (3.8) (4.2)
Debt 646.2 645.8
Long term debt, senior note matured on March 2020 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 5.00%  
Principal amount of debt 850.0 850.0
Debt Instrument, Discount (0.1) (0.1)
Debt 849.9 849.9
Long term debt, senior note matured on November 2021 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 5.25%  
Principal amount of debt 600.0 600.0
Debt Instrument, Discount 0 0
Debt 600.0 600.0
Long term debt, senior note matured on May 2023 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 4.75%  
Principal amount of debt 550.0 0
Debt Instrument, Discount (1.4) 0
Debt 548.6 0
Long term debt, senior note matured on March 2035 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 6.086%  
Principal amount of debt 275.7 275.6
Debt Instrument, Discount (25.5) (25.8)
Debt 250.2 249.8
Long term debt, senior note matured on March 2040 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 6.20%  
Principal amount of debt 650.0 650.0
Debt Instrument, Discount (0.5) (0.5)
Debt 649.5 649.5
Long term debt, senior note matured on May 2041 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 5.70%  
Principal amount of debt 600.0 0
Debt Instrument, Discount (3.4) 0
Debt 596.6 0
Long term debt, debentures matured on May 2021 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 9.25%  
Principal amount of debt 35.3 99.5
Debt Instrument, Discount (2.0) (6.1)
Debt 33.3 93.4
Long term debt, debentures matured on September 2035 [Member]
   
Debt    
Debt Instrument, Interest Rate, Percentage 7.40%  
Principal amount of debt 165.2 360.0
Debt Instrument, Discount (41.9) (92.4)
Debt 123.3 267.6
Tax-exempt bonds and other tax-exempt financings; maturities ranging from 2012 to 2035 [Member]
   
Debt    
Interest rate, minimum 0.06%  
Interest rate, maximum 8.25%  
Principal amount of debt 1,142.2 1,173.7
Debt Instrument, Discount (15.8) (21.9)
Debt 1,126.4 1,151.8
Other debt unsecured and secured by real property, equipment and other assets; interest rate maturing ranging from 2012 to 2042 [Member]
   
Debt    
Interest rate, minimum 5.00%  
Interest rate, maximum 11.90%  
Principal amount of debt 89.4 92.6
Debt Instrument, Discount 0 0
Debt $ 89.4 $ 92.6