Severance and Other Restructuring Costs - Additional Information (Detail) $ in Thousands		3 Months Ended		6 Months Ended		24 Months Ended
	Sep. 10, 2018 USD ($)	Jul. 31, 2018 USD ($)	Jul. 31, 2017 USD ($)	Jul. 31, 2018 USD ($) Employee	Jul. 31, 2017 USD ($)	Jul. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Severance and other restructuring costs		$ 536	$ 563	$ 590	$ 2,710
Additional severance charges		$ 500		$ 700
Number of employees terminated | Employee				12
Severance costs			$ 200		$ 200
Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges incurred						$ 7,100
Restructuring Plan [Member] | Subsequent Event [Member]
Restructuring Cost and Reserve [Line Items]
Annualized cost savings	$ 6,000
Severance and other restructuring costs	$ 1,000