v2.4.0.6
Borrowings (Details) (USD $)
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Sep. 30, 2010
Mar. 31, 2009
Fixed-Rate Notes [Member]
Dec. 31, 2010
ESOP debentures, 6.55% [Member]
Notes Payable $ 6,387,400,000 $ 6,387,400,000     $ 2,400,000,000  
Other Notes Payable 37,600,000 97,200,000       63,700,000
Long-term Debt, Fair Value Adjustment 556,500,000 304,100,000        
Long-term Debt, Total 6,981,500,000 6,788,700,000        
Long-term Debt, Current Maturities (1,516,800,000) (18,200,000)        
Long-term debt 5,464,700,000 6,770,500,000        
Short-term Bank Loans and Notes Payable 5,500,000 137,800,000   125,000,000    
Description of Derivative Activity Volume Percent 70.00%          
Debt Instrument, Interest Rate, Stated Percentage           6.55%
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 1,510,000,000          
Long-term Debt, Maturities, Repayments of Principal in Year Two 10,200,000          
Long-term Debt, Maturities, Repayments of Principal in Year Three 1,010,000,000          
Long-term Debt, Maturities, Repayments of Principal in Year Four 5,300,000          
Long-term Debt, Maturities, Repayments of Principal in Year Five 201,200,000          
Line of Credit Facility, Remaining Borrowing Capacity 1,240,000,000          
Line of Credit Facility, Collateral, Amount 1,200,000,000          
Interest Paid, Net $ 167,400,000 $ 176,300,000 $ 205,900,000      
Debt Instrument, Interest Rate, Effective Percentage 3.00% 2.87%