Income Taxes - Income Tax Expense (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Apr. 29, 2018	Jan. 28, 2018	Oct. 29, 2017	Jul. 30, 2017	Apr. 30, 2017	Jan. 29, 2017	Oct. 30, 2016	Jul. 31, 2016	Apr. 29, 2018	Apr. 30, 2017	May 01, 2016
current
federal										$ (1,367)	$ 109
state										9	13	$ 6
2017 Tax Cuts and Jobs Act										4,854
foreign										4,726	5,981	6,765
foreign - reversal of uncertain tax position											(3,431)
current income tax expense										8,222	2,672	6,771
deferred
federal										4,295	404	(1,205)
state										112	54	305
2017 Tax Cuts and Jobs Act	[1]									(6,903)
undistributed earnings - foreign subsidiaries										(195)	(101)	(1,129)
U.S. operating loss carryforwards											3,630	5,467
foreign										93	734	1,086
valuation allowance	[1]									116	(54)	(332)
deferred income tax expense										(2,482)	4,667	4,192
income tax expense		$ (6,217)	$ 8,208	$ 2,108	$ 1,640	$ 778	$ 643	$ 2,684	$ 3,233	$ 5,740	$ 7,339	$ 10,963

[1] The income tax benefit of $6,903 includes a charge of $4,550 for the establishment of a valuation allowance against U.S. foreign tax credits that are more-likely-than not to be realized as a result of the 2017 Tax Cuts and Jobs Act.