Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jan. 28, 2017	Apr. 30, 2016
Assets:
Cash equivalents	$ 1,821	$ 14,609
Deferred purchase price receivable	128,015	108,837
Derivative instruments	2,069	816
Total assets	131,905	124,262
Liabilities:
Derivative instruments	2,069	816
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents	1,821	14,609
Deferred purchase price receivable	0	0
Derivative instruments	0	0
Total assets	1,821	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	2,069	816
Total assets	2,069	816
Liabilities:
Derivative instruments	2,069	816
Fair Value, Inputs, Level 3 [Member]
Assets:
Cash equivalents	0	0
Deferred purchase price receivable	128,015	108,837
Derivative instruments	0	0
Total assets	128,015	108,837
Liabilities:
Derivative instruments	$ 0	$ 0