Debt (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 28, 2012	Apr. 30, 2011	Apr. 28, 2012 Senior Notes 4.63%	Apr. 30, 2011 Senior Notes 4.63%	Mar. 31, 2008 Senior Notes 4.63%	Apr. 28, 2012 Senior Notes 5.17%	Apr. 30, 2011 Senior Notes 5.17%	Mar. 31, 2008 Senior Notes 5.17%	Apr. 28, 2012 Senior Notes 5.75%	Apr. 30, 2011 Senior Notes 5.75%	Mar. 31, 2008 Senior Notes 5.75%	Apr. 28, 2012 Senior Notes 2.95%	Dec. 31, 2011 Senior Notes 2.95%	Apr. 30, 2011 Senior Notes 2.95%	Apr. 28, 2012 Senior Notes 3.59%	Dec. 31, 2011 Senior Notes 3.59%	Apr. 30, 2011 Senior Notes 3.59%	Apr. 28, 2012 Senior Notes 3.74%	Dec. 31, 2011 Senior Notes 3.74%	Apr. 30, 2011 Senior Notes 3.74%	Apr. 28, 2012 Term Note Due Fiscal 2013	Apr. 30, 2011 Term Note Due Fiscal 2013	Mar. 31, 2008 Term Note Due Fiscal 2013
Debt Instrument [Line Items]
Fixed rate senior notes due fiscal 2013 to 2023			$ 50,000	$ 50,000	$ 50,000	$ 250,000	$ 250,000	$ 250,000	$ 150,000	$ 150,000	$ 150,000	$ 60,000	$ 60,000	$ 0	$ 165,000	$ 165,000	$ 0	$ 100,000	$ 100,000	$ 0
Variable rate (LIBOR plus 1.25%) term loan due fiscal 2013																					75,000	75,000	75,000
Total debt	850,000	525,000
Less: current debt obligations	125,000	0
Long-term debt	$ 725,000	$ 525,000