CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 132.2	$ 66.7	$ 296.9	$ 82.7
Other comprehensive (loss) income, net of reclassifications:
Net loss on derivative instruments (net of tax effect of ($0.4), $0.4, $1.5 and ($1.6), respectively)	3.9	(3.3)	(11.6)	(4.3)
Change in net unrealized gain (loss) on available-for-sale debt securities (net of tax effect of zero, ($0.1), $0.1 and ($0.4), respectively)	0.6	0.5	1.9	1.4
Change in defined benefit pension items (net of tax effect of zero, $0.3, zero and $0.8, respectively)	0.3	(0.1)	0.0	(2.5)
Net change in cumulative foreign currency translation gain (loss) (net of tax effect of $0.1, $0.1, ($0.3) and $0.1, respectively)	(6.7)	17.3	13.6	(15.9)
Total other comprehensive (loss) income	(1.9)	14.4	3.9	(21.3)
Total comprehensive income	$ 130.3	$ 81.1	$ 300.8	$ 61.4