Business and Summary of Significant Accounting Policies - Accounts Receivable, Net (Details) - USD ($) $ in Millions	Jan. 31, 2016	Jan. 31, 2015
Accounting Policies [Abstract]
Trade accounts receivable	$ 700.1	$ 495.4
Less: Allowance for doubtful accounts	(7.6)	(6.3)
Product returns reserve	(1.6)	(2.6)
Partner programs and other obligations	(37.3)	(27.6)
Accounts receivable, net	$ 653.6	$ 458.9