Operating Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease, expense	$ 2.4		$ 6.8
Weighted-average remaining lease term	7 years		7 years
Weighted-average discount rate	5.10%		5.10%
Operating lease that has not yet commenced with undiscounted cash flows	$ 21.0		$ 21.0
Rent expense		$ 2.1		$ 5.1
Maximum
Lessee, Lease, Description [Line Items]
Lease contractual period	10 years		10 years