Summary of Business and Significant Accounting Policies - Additional Information (Detail) - Customer	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Summary Of Business And Accounting Policies [Line Items]
Period of amortization			3 years
Customer concentration risk [Member] | Revenues [Member]
Summary Of Business And Accounting Policies [Line Items]
Number of customers	0	0	0	0
Minimum [Member]
Summary Of Business And Accounting Policies [Line Items]
Customer payment period			30 days
Maximum [Member]
Summary Of Business And Accounting Policies [Line Items]
Customer payment period			60 days