Stockholders' Equity Share Repurchase Table (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Equity [Abstract]
Cost of repurchases	$ 30.8	$ 60.5	$ 180.7	$ 116.2
Purchase and retirement of Common Stock, Shares	0.5	0.8	2.8	1.4
Average cost per share	$ 67.72	$ 80.31	$ 65.13	$ 84.03