Retirement Benefit Plans (Defined Contribution Plans) (Details) (USD $)
In Millions
3 Months Ended 6 Months Ended
Jul. 30, 2011
Jul. 31, 2010
Jul. 30, 2011
Jul. 31, 2010
Retirement Benefit Plans        
Defined contribution plan, total expense $ 16 $ 12 $ 32 $ 26