Repurchase of Common Stock Accelerated Share Repurchase (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Apr. 30, 2016	Jan. 30, 2016
Accelerated Share Repurchases [Line Items]
Stock Repurchased and Retired During Period, Value	$ 45	$ 120
Stock Repurchased During Period, Value	101
Accelerated Share Repurchase Program, Adjustment	10
Accelerated Share Repurchase Settlement Amount	$ 165
Prepaid repurchase of common stock		(55)
Accelerated Share Repurchase Price (low end of the range)		150
Accelerated Share Repurchase Price (high end of the range)		$ 175
Stock Repurchased and Retired During Period, Shares	1.7