Retirement Benefit Plans (Details) (USD $)
In Millions
3 Months Ended 6 Months Ended
Jul. 30, 2011
Jul. 31, 2010
Jul. 30, 2011
Jul. 31, 2010
Service cost $ 22 $ 22 $ 45 $ 45
Interest cost 65 65 130 131
Expected return on plan assets (97) (88) (193) (176)
Net amortization 38 64 75 127
Net periodic benefit expense / (income) 28 63 57 127
Benefits Plan Primary Plan [Member]
       
Service cost 22 22 44 44
Interest cost 62 62 124 124
Expected return on plan assets (97) (88) (193) (176)
Net amortization 34 59 68 118
Net periodic benefit expense / (income) 21 55 43 110
Benefits Supplemental Plan [Member]
       
Service cost     1 1
Interest cost 3 3 6 7
Net amortization 4 5 7 9
Net periodic benefit expense / (income) 7 8 14 17
Postretirement Health and Welfare Plan [Member]
       
Net amortization (7) (6) (13) (12)
Net periodic benefit expense / (income) $ (7) $ (6) $ (13) $ (12)