Leases - ASC 842 Quantitative Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Leases [Abstract]
Operating lease cost	$ 1,472	$ 1,320	$ 2,912	$ 2,700
Short-term lease cost	124	82	160	136
Short-term sublease income	(10)	(20)	(20)	(30)
Variable lease cost	(85)	61	370	509
Total lease cost	$ 1,501	$ 1,443	3,422	3,315
Cash paid for amounts included in the measurement of lease liabilities			2,201	2,611
Right-of-use assets obtained in exchange for new lease liabilities			$ 398	$ 1,036
Weighted-average remaining lease term (years)	4 years 6 months	5 years 4 months 24 days	4 years 6 months	5 years 4 months 24 days
Weighted-average discount rate	6.40%	6.38%	6.40%	6.38%