Annual report pursuant to Section 13 and 15(d)

Postretirement Health Care and Life Insurance Benefits (Weighted Average Assumptions Used To Determine Projected Benefit Obligations For Postretirement Obligations) (Details)

v3.8.0.1
Postretirement Health Care and Life Insurance Benefits (Weighted Average Assumptions Used To Determine Projected Benefit Obligations For Postretirement Obligations) (Details)
Feb. 03, 2018
Jan. 28, 2017
Other Postretirement Benefits Plan [Member]    
Discount rate 3.71% 3.99%