Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Aug. 01, 2015	Apr. 25, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	$ 10,701	$ 90,569
Derivative instruments, assets	1,124	1,255
Total assets	11,825	91,824
Derivative instruments, liabilities	1,124	1,255
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	10,701	90,569
Total assets	10,701	90,569
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, assets	1,124	1,255
Total assets	1,124	1,255
Derivative instruments, liabilities	$ 1,124	$ 1,255