Financing Arrangements - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Apr. 24, 2015 Extension	Apr. 25, 2014	Apr. 26, 2013	Jun. 10, 2008
Debt Instrument [Line Items]
Notes issued, principal amount	$ 1,500,000,000	1,000,000,000
Notes issued, issuance discount	5,000,000	4,500,000
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, amount	250,000,000
Credit facility, date expiry	Dec. 21, 2017
Credit facility, increase in facility	100,000,000
Credit facility, number of extensions	2
Credit facility, extensions period	1 year
Credit facility, outstanding borrowings	0
Common Stock
Debt Instrument [Line Items]
Conversion of convertible notes		4.9
Minimum | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, base rate	0.20%
Interest coverage ratio	350.00%
Maximum | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, base rate	1.20%
Leverage ratio	300.00%
Put Option | Common Stock
Debt Instrument [Line Items]
Convertible Note Hedge number of shares contracted to sell			31.8
Convertible Note Hedge Exercise Price			$ 31.85
Convertible note hedge and warrants exercised and settled with shares of common stock		(3.9)
Warrant | Common Stock
Debt Instrument [Line Items]
Convertible note hedge and warrants exercised and settled with shares of common stock		1.1
Outstanding warrants, number of shares		39.7
Exercise price of warrants		41.28
Warrants exercised, number of shares		31.9
Warrant | Weighted Average | Common Stock
Debt Instrument [Line Items]
Exercise price of warrants		43.09
Convertible Notes Payable
Debt Instrument [Line Items]
Notes issued, principal amount				1,265,000,000
Notes issued, interest rate				1.75%
Convertible Notes, maturity date		Jun. 01, 2013
Conversion factor for convertible notes		31.40
Denominator of principal amount upon which conversion rate is based		1,000
Conversion price of notes to shares of common stock		31.85
Conversion of convertible notes		4.9
Excess conversion value over principal amount of Convertible Notes		178,900,000
Long-term debt				1,017,000,000
Effective interest rate				6.31%
Notes issued, issuance discount				248,000,000
Issuance costs on Convertible Notes				21,400,000
Equity Components Of Convertible Notes
Debt Instrument [Line Items]
Issuance costs on Convertible Notes				5,200,000
Foreign Currency Sub Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, amount	100,000,000
Letter Of Credit Sub Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, amount	50,000,000
Swingline Sub Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, amount	10,000,000
Senior Notes
Debt Instrument [Line Items]
Long-term debt	1,523,600,000	1,000,000,000
Senior Notes | Due 2021
Debt Instrument [Line Items]
Notes issued, principal amount	500,000,000	0
Effective interest rate	3.54%
Senior Notes | Due 2017
Debt Instrument [Line Items]
Notes issued, principal amount	750,000,000	750,000,000
Effective interest rate	2.25%	2.25%
Senior Notes | Due 2022
Debt Instrument [Line Items]
Notes issued, principal amount	$ 250,000,000	250,000,000
Effective interest rate	3.43%	3.43%