Deferred Tax Amounts (Detail) - USD ($) $ in Thousands	Apr. 30, 2016	Apr. 30, 2015
Income Taxes [Line Items]
Non-current deferred tax assets	$ 162,505	$ 121,906
Non-current deferred tax liabilities	(118,400)	(40,457)
Valuation allowance	(22,030)	(21,608)
Net non-current deferred tax assets	$ 22,075	$ 59,841