Segment Information - International net sales (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 28, 2013	Jan. 27, 2013	Oct. 28, 2012	Jul. 29, 2012	Apr. 29, 2012	Jan. 29, 2012	Oct. 30, 2011	Jul. 31, 2011	Apr. 28, 2013	Apr. 29, 2012	May 01, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales	$ 70,375	$ 63,695	$ 65,560	$ 69,184	$ 75,711	$ 60,450	$ 58,013	$ 60,270	$ 268,814	$ 254,443	$ 216,806
North america (excluding USA) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales									11,900	10,417	10,505
Far east and asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales									43,907	38,279	36,587
All other areas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales									5,806	5,353	1,502
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales									$ 61,613	$ 54,049	$ 48,594