Employees' Defined Contribution Plan - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2015	Nov. 01, 2014	Oct. 31, 2015	Nov. 01, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions, employee benefit expenses	$ 1,020	$ 897	$ 2,295	$ 2,024