Stock Compensation Plans Option Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding, Shares, beginning of period	2.3
Granted, Shares	0.7
Exercised, Shares	(0.8)
Forfeited/canceled, Shares	(0.5)
Outstanding, Shares, end of period	1.7	2.3
Exercisable, Shares	0.7
Outstanding, Weighted Average Exercise Price, beginning of period	$ 70.72
Granted, Weighted Average Exercise Price	100.25
Exercised, Weighted Average Exercise Price	65.72
Forfeited/canceled, Weighted Average Exercise Price	74.15
Outstanding, Weighted Average Exercise Price, end of period	84.25	$ 70.72
Exercisable, Weighted Average Exercise Price	$ 73.46
Outstanding, Weighted Average Remaining Contractual Term	7 years 10 months 12 days	7 years 6 months
Exercisable, Weighted Average Remaining Contractual Term	5 years 11 months 25 days
Outstanding, Intrinsic Value, beginning of period	$ 23.8
Outstanding, Intrinsic Value, end of period	41.1	$ 23.8
Exercisable, Intrinsic Value	$ 23.6