CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Statement of Comprehensive Income [Abstract]
Net gain on derivative instruments, tax expense (benefit)	$ (3.3)	$ (0.4)	$ (6.7)	$ 1.5
Change in net unrealized gain on available-for-sale securities, tax expense (benefit)	0.0	0.0	0.0	0.1
Change in defined pension items, tax expense (benefit)	0.0	0.0	0.0	0.0
Net change in cumulative foreign currency translation (loss) gain, tax expense (benefit)	$ (0.3)	$ 0.1	$ (0.9)	$ (0.3)