CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Statement of Comprehensive Income [Abstract]
Net gain (loss) on derivative instruments, tax effect	$ (1.1)	$ 0.3	$ (2.9)	$ 1.7
Change in net unrealized gain on available-for-sale debt securities, tax effect	(0.1)	(0.4)	(0.1)	(0.3)
Change in defined benefit pension items, tax effect	(1.3)	0.0	(2.8)	0.0
Net change in cumulative foreign currency translation (loss) gain, tax effect	$ 0.0	$ 0.0	$ 0.5	$ (0.9)