Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Schedule Of Income Taxes [Line Items]
Undistributed earning of foreign subsidiaries	$ 375,200,000
Unrecognized tax benefits liability	2,095,000	$ 2,423,000	$ 2,701,000	$ 3,400,000
Unrecognized tax benefits, reductions resulting from resolution	(300,000)
Unrecognized tax benefits, accrued interest and penalties	0	700,000
Unrecognized tax benefits, interest	100,000	100,000	$ 100,000
Internal Revenue Service (IRS)
Schedule Of Income Taxes [Line Items]
Net operating loss carryforward	$ 3,900,000
Net operating loss carryforward, beginning expiration	2028
Accounting Standards Update 2015-17
Schedule Of Income Taxes [Line Items]
Reclassification of deferred tax assets from current to non current		$ 3,800,000
State and Local Jurisdiction
Schedule Of Income Taxes [Line Items]
Net operating loss carryforward	$ 33,800,000
Net operating loss carryforward, beginning expiration	2017
Foreign Tax Authority
Schedule Of Income Taxes [Line Items]
Net operating loss carryforward	$ 105,100,000
Net operating loss carryforward, beginning expiration	2017