Summary of Significant Accounting Policies - Advertising (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Accounting Policies [Abstract]
Advertising, marketing, public and media relations costs	$ 394.1	$ 314.9	$ 299.0
Advertising costs as percentage of net sales (percentage)	8.90%	7.60%	7.50%