Interest and Other Expense, net (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Other Income and Expenses [Abstract]
Interest and investment expense, net	$ (52.1)	$ (34.5)	$ (29.7)
Gain (loss) on foreign currency	5.1	(3.3)	(3.3)
Gain (loss) on strategic investments	12.5	(16.4)	0.3
Other income	16.8	6.0	8.5
Interest and other expense, net	$ (17.7)	$ (48.2)	$ (24.2)