Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Leases [Abstract]
Operating lease expense	$ 0.7	$ 0.7	$ 1.4	$ 1.5
Weighted-average remaining lease term - operating leases	4 years 9 months 3 days		4 years 9 months 3 days
Weighted-average discount rate - operating leases	4.43%		4.43%