Income Tax (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Tax Credit Carryforward [Line Items]
Provision for income taxes	$ 50.7	$ 23.9	$ 49.7	$ 78.7
(Loss) income before income taxes	187.4	$ 156.1	457.6	$ 375.6
Unrecognized tax benefits	204.6		204.6
Unrecognized tax benefits that would impact effective tax rate	171.1		171.1
Effect of change in unrecognized tax benefits	8.0		8.0
SEC Schedule, 12-09, Valuation Allowance, Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits that would impact effective tax rate	$ 33.5		$ 33.5