CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Statement of Comprehensive Income [Abstract]
Net (loss) on derivative instruments, tax effect	$ 0.9	$ 1.1	$ 1.4	$ (0.8)
Change in net unrealized gain (loss) on available-for-sale securities, tax effect	0.4	(0.1)	0.1	(0.6)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	0.0	(0.2)	0.0	(0.2)
Net change in cumulative foreign currency translation loss, tax effect	$ (0.6)	$ 0.0	$ (0.9)	$ 0.0