Business and Summary of Significant Accounting Policies - Accounts Receivable, Net (Details) - USD ($) $ in Millions	Jan. 31, 2017	Jan. 31, 2016
Accounting Policies [Abstract]
Trade accounts receivable	$ 477.5	$ 700.1
Less: Allowance for doubtful accounts	(1.5)	(7.6)
Product returns reserve	(0.2)	(1.6)
Partner programs and other obligations	(23.5)	(37.3)
Accounts receivable, net	$ 452.3	$ 653.6