Components of Deferred Tax Assets (Liabilities) (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 28, 2012	Apr. 30, 2011
Income Taxes [Line Items]
Capital Accumulation Plan	$ 4,045	$ 4,048
Inventory obsolescence	2,124	3,455
Bad debt allowance	2,022	2,424
LIFO reserve	(12,773)	(14,755)
Other	17,544	14,229
Deferred net current income tax asset	12,962	9,401
Amortizable intangibles	(29,142)	(30,033)
Goodwill	(56,026)	(49,089)
Property, plant, equipment	(3,901)	(3,737)
Stock based compensation expense	7,897	6,146
Net operating loss carryforwards	7,656	9,431
Other	(3,568)	(4,612)
Deferred long-term income tax (liability) asset	(77,084)	(71,894)
Valuation allowance	(4,772)	(6,345)
Deferred net long-term income tax liability	(81,856)	(78,239)
Net deferred income tax liability	$ (68,894)	$ (68,838)