CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 115.6	$ 98.2	$ 271.2	$ 164.7
Other comprehensive (loss) income, net of reclassifications:
Net gain (loss) on derivative instruments (net of tax effect of $(1.7), $2.3, $(3.4) and $1.9, respectively)	9.5	(19.5)	19.5	(15.5)
Change in net unrealized gain on available-for-sale debt securities (net of tax effect of zero, zero, zero and $0.1, respectively)	3.8	0.9	7.8	1.3
Change in defined benefit pension items (net of tax effect of zero for all periods presented)	0.1	0.0	0.2	(0.3)
Net change in cumulative foreign currency translation (loss) gain (net of tax effect of $1.2, $(0.4), $(0.6) and $(0.4), respectively)	(25.1)	43.2	(15.0)	20.3
Total other comprehensive (loss) income	(11.7)	24.6	12.5	5.8
Total comprehensive income	$ 103.9	$ 122.8	$ 283.7	$ 170.5