Stock-Based Compensation Expense in Selling and Administrative Expenses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 30, 2016	Jan. 31, 2015	Jan. 30, 2016	Jan. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,999	$ 2,975	$ 10,943	$ 14,243
Selling and Administrative Expenses | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	210	248	600	799
Selling and Administrative Expenses | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,573	2,599	9,487	11,823
Selling and Administrative Expenses | Performance Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	189		439
Selling and Administrative Expenses | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 27	$ 128	$ 417	$ 1,621