Annual report pursuant to Section 13 and 15(d)

Postretirement Health Care and Life Insurance Benefits (One Percentage Point Change In Assumed Health Care Cost Rates Would Have The Following Effects) (Details)

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Postretirement Health Care and Life Insurance Benefits (One Percentage Point Change In Assumed Health Care Cost Rates Would Have The Following Effects) (Details)
$ in Millions
12 Months Ended
Jan. 30, 2016
USD ($)
Postretirement Medical Plans with Prescription Drug Benefits [Abstract]  
Effect on total of service and interest cost, 1 - percentage point increase $ 1
Effect on total of service and interest cost, 1 - percentage point decrease (1)
Effect on accumulated postretirement benefit obligations, 1 - percentage point increase 15
Effect on accumulated postretirement benefit obligations, 1 - percentage point decrease $ (13)