Presentation and Summary of Significant Accounting Policies - Summary of Effect of Adopting Topic 606 on Condensed Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2018	Jul. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred income taxes	$ 28	$ 120
Accounts receivable, net	5,466	3,504
Prepaid expenses and other assets	330	255
Accounts payable and other liabilities	(4,223)	(2,669)
Deferred revenue	(3,334)	$ (1,079)
Balances under Prior GAAP
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred income taxes	607
Accounts receivable, net	5,026
Prepaid expenses and other assets	(1,121)
Accounts payable and other liabilities	(4,143)
Deferred revenue	(3,855)
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred income taxes	579
Accounts receivable, net	(440)
Prepaid expenses and other assets	(1,451)
Accounts payable and other liabilities	80
Deferred revenue	$ (521)