Postretirement Health Care and Life Insurance Benefits (Reconciliation Of Benefit Obligations, Plan Assets, And Funded Status Of The Postretirement Obligations) (Details) - Other Postretirement Benefit Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Jan. 28, 2017	Jan. 30, 2016	Jan. 31, 2015
Projected benefit obligation, beginning of year	$ 212	$ 243
Service cost	0	0	$ 0
Interest cost	6	8	10
Actuarial (gain) loss	(13)	(22)
Medicare Part D subsidy	1	1
Benefits paid	(20)	(18)
Projected benefit obligation, end of year	186	212	243
Fair value of plan assets, beginning of year	0	0
Company contributions	20	18
Fair value of plan assets, end of year	0	0	$ 0
Funded status at end of year	186	212
Accounts payable and accrued liabilities	(18)	(20)
Other liabilities	(168)	(192)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(186)	(212)
Net actuarial (gain) loss	(31)	$ (22)
Defined Benefit Plan, Future Amortization of Gain (Loss)	$ 4