Leases (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Lessee, Lease, Description
Operating lease cost	$ 20.6	$ 11.1	$ 38.4	$ 22.4
Variable Lease, Cost	4.7		7.3
Leases not yet commenced, future lease payments	$ 8.3		$ 8.3
Term of office lease	11 years		11 years