Annual report pursuant to Section 13 and 15(d)

Postretirement Health Care and Life Insurance Benefits (Weighted Average Assumptions Used To Determine Net Periodic Costs For Postretirement Plans) (Details)

v3.7.0.1
Postretirement Health Care and Life Insurance Benefits (Weighted Average Assumptions Used To Determine Net Periodic Costs For Postretirement Plans) (Details)
12 Months Ended
Jan. 28, 2017
Jan. 30, 2016
Jan. 31, 2015
Other Postretirement Benefit Plan [Member]      
Discount rate 3.14% 3.55% 4.50%