Accounts Receivable - Rollforward of Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2021	Jul. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 21.4	$ 25.5
Provision for credit losses	0.8	(0.4)
Write-offs	(2.6)	(5.5)
Reversal of allowance on receivables sold	(19.6)	(19.6)
Ending balance	$ 0.0	$ 0.0