Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 28, 2012	Apr. 30, 2011	Apr. 24, 2010
Allowance for doubtful accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 8,365	$ 9,111	$ 9,773
Charged to Costs and Expenses	2,445	3,409	4,579
Charged to Other Accounts
Deductions	2,979	4,155	5,241
Balance at End of Period	7,831	8,365	9,111
LIFO inventory adjustment
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	61,385	56,961	51,934
Charged to Costs and Expenses	5,422	4,424	5,027
Charged to Other Accounts
Balance at End of Period	66,807	61,385	56,961
Inventory obsolescence reserve
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	5,844	8,329	8,381
Charged to Costs and Expenses	11,508	10,403	10,347
Charged to Other Accounts
Deductions	11,896	12,888	10,399
Balance at End of Period	5,456	5,844	8,329
Total inventory reserve
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	67,229	65,290	60,315
Charged to Costs and Expenses	16,930	14,827	15,374
Charged to Other Accounts
Deductions	11,896	12,888	10,399
Balance at End of Period	$ 72,263	$ 67,229	$ 65,290