v2.4.0.6
Postretirement Healthcare Benefit Plans (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
U.S. and foreign postretirement healthcare benefits
      
Amounts Recognized in the Balance Sheet Consist Of:      
Prior service cost (credit) included in accumulated other comprehensive income that is expected to be recognized in net periodic benefit costs in 2012 $ 1    
Prior service cost (credit) included in accumulated other comprehensive income that is expected to be recognized in net periodic benefit costs in 2012, net of tax 1    
Net actuarial loss included in accumulated other comprehensive income that is expected to be recognized in net periodic benefit costs in 2012 1    
Net actuarial loss included in accumulated other comprehensive income that is expected to be recognized in net periodic benefit costs in 2012, net of tax 1    
U.S. postretirement healthcare benefits
      
Change in Benefit Obligations:      
Benefit obligation as of beginning of year 20 26  
Interest cost 1 2 2
Actuarial (gain) loss, net (3) (6)  
Employee contributions 1 1  
Benefits paid (2) (3)  
Benefit obligation as of end of year 17 20 26
Change in Plan Assets:      
Employer contributions 1 2  
Employee contributions 1 1  
Benefits paid (2) (3)  
Funded Status and Net Amounts Recognized:      
Plan assets less than benefit obligation (17) (20)  
Net liability recognized in the balance sheet (17) (20)  
Amounts Recognized in the Balance Sheet Consist Of:      
Current liabilities (2) (2)  
Non-current liabilities (15) (18)  
Net (liability) asset recognized (17) (20)  
Unrecognized prior service cost 1    
Unrecognized prior service cost, net of tax 1    
Unrecognized actuarial gain (loss) 4    
Unrecognized actuarial gain (loss), net of tax 3    
Net Periodic Benefit Cost:      
Interest cost 1 2 2
Net periodic benefit cost 1 2 2
Weighted-Average Assumptions to Determine Benefit Obligations      
Discount rate (as a percent) 4.80% 5.30%  
Weighted-Average Assumptions to Determine the Net Periodic Benefit Cost      
Discount rate (as a percent) 5.30% 5.80% 6.50%
Annual rate of increase in the per capita cost of covered health care benefits assumed (as a percent) 10.42% 11.18%  
Annual rate of decrease in the per capita cost of covered health care through 2029 and thereafter (as a percent) 4.50%    
One-Percentage-Point Change in Assumed Health Care Cost Trend Rates      
Effect of a one-percentage-point increase to postretirement benefit obligation 1    
Effect of a one-percentage-point decrease to postretirement benefit obligation (1)    
Estimated contribution by employer, next fiscal year 2    
Defined Benefit Pension Plans, Estimated Future Benefit Payments      
2012 2    
2013 2    
2014 2    
2015 2    
2016 2    
2017-2021 6    
Foreign postretirement healthcare benefits
      
Change in Benefit Obligations:      
Benefit obligation as of beginning of year 100 111  
Service cost 1 1 2
Interest cost 10 10 10
Actuarial (gain) loss, net 8 12  
Plan settlements/divestitures   (32)  
Effect of acquisitions   1  
Benefits paid (10) (8)  
Impact of foreign exchange rates (12) 5  
Benefit obligation as of end of year 97 100 111
Change in Plan Assets:      
Employer contributions 10 8  
Benefits paid (10) (8)  
Funded Status and Net Amounts Recognized:      
Plan assets less than benefit obligation (97) (100)  
Net liability recognized in the balance sheet (97) (100)  
Amounts Recognized in the Balance Sheet Consist Of:      
Current liabilities (7) (8)  
Non-current liabilities (90) (92)  
Net (liability) asset recognized (97) (100)  
Unrecognized prior service cost 4    
Unrecognized prior service cost, net of tax 3    
Unrecognized actuarial gain (loss) (17)    
Unrecognized actuarial gain (loss), net of tax (11)    
Net Periodic Benefit Cost:      
Service cost 1 1 2
Interest cost 10 10 10
Amortization of prior service cost (1) (1)  
Amortization of net loss (gain) 1 2  
Settlement gain recognized   (26)  
Net periodic benefit cost 11 (14) 12
Weighted-Average Assumptions to Determine Benefit Obligations      
Discount rate (as a percent) 10.30% 10.80%  
Weighted-Average Assumptions to Determine the Net Periodic Benefit Cost      
Discount rate (as a percent) 10.80% 11.30% 12.40%
Annual rate of increase in the per capita cost of covered health care benefits assumed (as a percent) 7.63% 8.07%  
One-Percentage-Point Change in Assumed Health Care Cost Trend Rates      
Effect of a one-percentage-point increase to total of service and interest cost components 2    
Effect of a one-percentage-point decrease to total of service and interest cost components (1)    
Effect of a one-percentage-point increase to postretirement benefit obligation 15    
Effect of a one-percentage-point decrease to postretirement benefit obligation (11)    
Estimated contribution by employer, next fiscal year 6    
Defined Benefit Pension Plans, Estimated Future Benefit Payments      
2012 6    
2013 7    
2014 7    
2015 7    
2016 8    
2017-2021 42    
Foreign postretirement healthcare benefits | Fertilizer nutrients assets in Brazil
      
Change in Benefit Obligations:      
Plan settlements/divestitures   $ (32)