Income Taxes - Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Current tax expense:
Federal	$ 1,719	$ 891	$ 974
State and local	311	120	117
Foreign	1,414	1,467	1,122
Total current tax expense	3,444	2,478	2,213
Deferred tax expense (benefit):
Federal	401	(108)	(431)
State and local	28	24	98
Foreign	242	(268)	(18)
Total deferred tax expense (benefit)	671	(352)	(351)
Net income tax expense	$ 4,115	$ 2,126	$ 1,862