Operating Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease, expense	$ 2.5		$ 4.9
Short-term lease expense	$ 0.3		$ 0.5
Weighted-average remaining lease term	7 years 2 months 12 days		7 years 2 months 12 days
Weighted-average discount rate	5.10%		5.10%
Operating lease that has not yet commenced with undiscounted cash flows	$ 25.5		$ 25.5
Rent expense		$ 1.6		$ 3.0
Maximum
Lessee, Lease, Description [Line Items]
Lease contractual period	10 years		10 years