Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	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
Property, Plant and Equipment [Line Items]
land and improvements	$ 963				$ 836
buildings and improvements	31,022				19,071
leasehold improvements	1,993				1,541
machinery and equipment	72,924				67,709
office furniture and equipment	9,514				8,936
capital projects in progress	2,086				12,901
property, plant and equipment, gross	118,502				110,994
accumulated depreciation and amortization	(66,708)				(59,343)
property, plant and equipment, net	$ 51,794	$ 51,838	$ 52,530	$ 52,912	$ 51,651	$ 50,333	$ 45,537	$ 41,745
land and improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	0 years
land and improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	10 years
buildings and improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	7 years
buildings and improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	40 years
leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	Shorter of life of lease or useful life.
machinery and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	3 years
machinery and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	12 years
office furniture and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	3 years
office furniture and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
depreciable lives	10 years