Commitments and Contingencies - Schedule of Product Warranty Liabilities and Balances Reported in Condensed Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 24, 2014	Oct. 25, 2013	Oct. 24, 2014	Oct. 25, 2013	Apr. 25, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 104.1	$ 119.8	$ 110.0	$ 117.2
Expense accrued during the period	8.3	14.3	18.8	38.3
Warranty costs incurred	(15.8)	(18.1)	(32.2)	(39.5)
Balance at end of period	96.6	116.0	96.6	116.0
Standard Product Warranty Accrual, Balance Sheet Classification [Abstract]
Other current liabilities	64.2		64.2		73.0
Other long-term liabilities	32.4		32.4		37.0
Total	$ 96.6	$ 116.0	$ 96.6	$ 116.0