v2.4.0.6
Debt (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Dec. 31, 2012
Debt    
Principal $ 7,112.1 $ 7,150.2
Discount (79.2) (79.7)
Carry Value 7,032.9 7,070.5
Less: Current portion (25.1) (19.4)
Long-term portion 7,007.8 7,051.1
Credit facilities: Uncommitted revolver [Member]
   
Debt    
Interest Rate Variable  
Principal 0 13.9
Discount 0 0
Carry Value 0 13.9
Credit facilities: April 2016 [Member]
   
Debt    
Interest Rate Variable  
Principal 0 25.0
Discount 0 0
Carry Value 0 25.0
Credit facilities: May 2017 [Member]
   
Debt    
Interest Rate Variable  
Principal 0 0
Discount 0 0
Carry Value 0 0
Senior notes: May 2018 [Member]
   
Debt    
Interest Rate (in percentage) 3.80%  
Principal 700.0 700.0
Discount (0.2) (0.2)
Carry Value 699.8 699.8
Senior notes: September 2019 [Member]
   
Debt    
Interest Rate (in percentage) 5.50%  
Principal 650.0 650.0
Discount (3.3) (3.4)
Carry Value 646.7 646.6
Senior notes: March 2020 [Member]
   
Debt    
Interest Rate (in percentage) 5.00%  
Principal 850.0 850.0
Discount (0.1) (0.1)
Carry Value 849.9 849.9
Senior notes: November 2021 [Member]
   
Debt    
Interest Rate (in percentage) 5.25%  
Principal 600.0 600.0
Discount 0 0
Carry Value 600.0 600.0
Senior notes: June 2022 [Member]
   
Debt    
Interest Rate (in percentage) 3.55%  
Principal 850.0 850.0
Discount (2.2) (2.2)
Carry Value 847.8 847.8
Senior notes: May 2023 [Member]
   
Debt    
Interest Rate (in percentage) 4.75%  
Principal 550.0 550.0
Discount (1.3) (1.3)
Carry Value 548.7 548.7
Senior notes: March 2035 [Member]
   
Debt    
Interest Rate (in percentage) 6.086%  
Principal 275.7 275.7
Discount (24.8) (24.9)
Carry Value 250.9 250.8
Senior notes: March 2040 [Member]
   
Debt    
Interest Rate (in percentage) 6.20%  
Principal 650.0 650.0
Discount (0.5) (0.5)
Carry Value 649.5 649.5
Senior notes: May 2041 [Member]
   
Debt    
Interest Rate (in percentage) 5.70%  
Principal 600.0 600.0
Discount (3.3) (3.4)
Carry Value 596.7 596.6
Debentures: May 2021 [Member]
   
Debt    
Interest Rate (in percentage) 9.25%  
Principal 35.3 35.3
Discount (1.8) (1.9)
Carry Value 33.5 33.4
Debentures: September 2035 [Member]
   
Debt    
Interest Rate (in percentage) 7.40%  
Principal 165.3 165.2
Discount (41.4) (41.4)
Carry Value 123.9 123.8
Tax-exempt: 2013 - 2035 [Member]
   
Debt    
Interest rate, minimum 0.16%  
Interest rate, maximum 5.625%  
Principal 1,096.7 1,097.9
Discount (0.3) (0.4)
Carry Value 1,096.4 1,097.5
Other: 2013 - 2046 [Member]
   
Debt    
Interest rate, minimum 5.00%  
Interest rate, maximum 11.90%  
Principal 89.1 87.2
Discount 0 0
Carry Value $ 89.1 $ 87.2