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	6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net earnings (loss)	$ 2,628	$ 5,205
Deferred income taxes	(265)	761
Changes in operating assets and liabilities:
Accounts receivable, net	2,162	3,243
Prepaid expenses and other assets	242	(1,758)
Accounts payable and other liabilities	(4,333)	(2,734)
Deferred revenue	(3,457)	$ (1,709)
Net cash provided by operating activities	(3,023)
Balances under Prior GAAP
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net earnings (loss)	2,595
Deferred income taxes	(270)
Changes in operating assets and liabilities:
Accounts receivable, net	2,111
Prepaid expenses and other assets	233
Accounts payable and other liabilities	(4,333)
Deferred revenue	(3,359)
Net cash provided by operating activities	(3,023)
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]
Net earnings (loss)	(33)
Deferred income taxes	(5)
Changes in operating assets and liabilities:
Accounts receivable, net	(51)
Prepaid expenses and other assets	(9)
Deferred revenue	$ 98