Litigation, Other Contingencies and Guarantees (Narrative) (Details) (USD $)
In Millions
3 Months Ended
Apr. 30, 2011
Litigation, Other Contingencies and Guarantees  
Estimate Potential Environmental Liabilities Minimum $ 35
Estimate Potential Environmental Liabilities Maximum 42
Recorded Best Estimate 36
Maximum Exposure of Guarantee 20
Guarantee Program Maximum $ 13