Postretirement Health Care and Life Insurance Benefits (Net Periodic Benefit Cost) (Details) - Other Postretirement Benefit Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Jan. 28, 2017	Jan. 30, 2016	Jan. 31, 2015
Service cost	$ 0	$ 0	$ 0
Interest cost	6	8	10
Amortization of net actuarial (gain) loss	(4)	0	(5)
Amortization of prior service credit	0	0	0
Total net periodic benefit cost	2	8	5
Net actuarial (gain) loss recognized in OCI before tax	(13)	(22)	30
Amortization of net actuarial loss	4	0	5
Amortization of prior service credit	0	0	0
Total recognized in other comprehensive income	(9)	(22)	35
Total recognized in net periodic benefit cost and other comprehensive income	$ (7)	$ (14)	$ 40