Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jan. 30, 2016	Apr. 25, 2015
Assets:
Cash equivalents	$ 5,151	$ 90,569
Derivative instruments	1,184	1,255
Total assets	6,335	91,824
Liabilities:
Derivative instruments	1,184	1,255
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents	5,151	90,569
Derivative instruments	0	0
Total assets	5,151	90,569
Liabilities:
Derivative instruments	0	0
Fair Value, Inputs, Level 2 [Member]
Assets:
Cash equivalents	0	0
Derivative instruments	1,184	1,255
Total assets	1,184	1,255
Liabilities:
Derivative instruments	1,184	1,255
Fair Value, Inputs, Level 3 [Member]
Assets:
Cash equivalents	0	0
Derivative instruments	0	0
Total assets	0	0
Liabilities:
Derivative instruments	$ 0	$ 0