Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Apr. 28, 2012		Apr. 30, 2011		Apr. 24, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Beginning balance	1,273		1,648		1,898
Number of Options, Granted	64		51		86
Number of Options, Exercised	(232)		(334)		(281)
Number of Options, Canceled	(119)		(92)		(55)
Number of Options, Ending balance	986		1,273		1,648
Number of Options, Vested or expected to vest at end of year	863
Number of Options, Exercisable at end of year	576
Exercise Price, Beginning balance	$ 29.82	[1]	$ 26.94	[1]	$ 25.24	[1]
Exercise Price, Granted	$ 33.90	[1]	$ 32.08	[1]	$ 20.76	[1]
Exercise Price, Exercised	$ 24.11	[1]	$ 17.82	[1]	$ 12.36	[1]
Exercise Price, Canceled	$ 29.64	[1]	$ 23.02	[1]	$ 33.15	[1]
Exercise Price, Ending balance	$ 31.45	[1]	$ 29.82	[1]	$ 26.94	[1]
Exercise Price, Vested or expected to vest at end of year	$ 31.15	[1]
Exercise Price, Exercisable at end of year	$ 29.94	[1]
Intrinsic Value, Balance at end of year	$ 4,453
Intrinsic Value, Vested or expected to vest at end of year	4,161
Intrinsic Value, Exercisable at end of year	$ 3,479

[1] Weighted-average exercise price