Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Oct. 29, 2016	Apr. 30, 2016
Assets:
Cash equivalents	$ 3,506	$ 14,609
Deferred purchase price receivable	118,059	108,837
Derivative instruments	790	816
Total assets	122,355	124,262
Liabilities:
Derivative instruments	790	816
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents	3,506	14,609
Deferred purchase price receivable	0	0
Derivative instruments	0	0
Total assets	3,506	14,609
Liabilities:
Derivative instruments	0	0
Fair Value, Inputs, Level 2 [Member]
Assets:
Cash equivalents	0	0
Deferred purchase price receivable	0	0
Derivative instruments	790	816
Total assets	790	816
Liabilities:
Derivative instruments	790	816
Fair Value, Inputs, Level 3 [Member]
Assets:
Cash equivalents	0	0
Deferred purchase price receivable	118,059	108,837
Derivative instruments	0	0
Total assets	118,059	108,837
Liabilities:
Derivative instruments	$ 0	$ 0