Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified						9 Months Ended
	Jan. 25, 2013	Apr. 27, 2012	Jan. 25, 2013 Contract Manufacturers	Jan. 25, 2013 Capital Purchase Commitments	Jan. 25, 2013 Other Purchase Commitments	Jan. 25, 2013 Software Maximum	Jan. 25, 2013 Software Minimum	Jan. 25, 2013 Hardware Maximum	Jan. 25, 2013 Hardware Minimum
Commitments and Contingencies Disclosure [Line Items]
Future annual minimum lease payments	$ 222.5
Accrued purchase commitments with contract manufacturers	8.1	3.3
Significant commitment			$ 282.4	$ 93.6	$ 182.3
Product warranty term						5 years	90 days	5 years	1 year