Income Taxes (Details) (USD $)
In Millions
3 Months Ended
Apr. 30, 2011
Jan. 29, 2011
Unrecognized tax benefits $ 145 $ 162
Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities 20  
Additions for tax positions of prior years 3  
Amount of unrecognized tax benefits that would impact effective tax rate if recognized 63  
Benefit of federal tax deduction of state taxes 22  
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Decrease to Unrecorded Benefit 41  
Accrued Interest for Unrecognized Tax Benefits 4 3
Potential Impact to Effective Tax Rate Next 12 Months [Member]
   
Amount of unrecognized tax benefits that would impact effective tax rate if recognized $ 1 Â